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  • Articles  (13,819)
  • Inorganic Chemistry  (6,921)
  • Organic Chemistry  (6,898)
  • 1985-1989  (6,907)
  • 1980-1984  (6,912)
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  • Articles  (13,819)
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  • 1
    Electronic Resource
    Electronic Resource
    The FDA perspective on the development of stereoisomers (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 2-6 
    Details
    ISSN: 0899-0042
    Keywords: optical isomers ; stereochemistry ; enantiomers ; Food and Drug Administration ; drug development ; drug regulation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The current regulatory position of the Food and Drug Administration is discussed with regard to the approval of racemates and pure stereoisomers. Circumstances in which stereochemically sensitive analytical methods are necessay to ensure the safety and efficacy of a drug are described. Regulatory guidelines are interpreted for applications for the approval of a pure enantiomer in which the racemate is marketed, for the approval of eitehr a racemate or a pure enantiomer in which neither is marketed, and for clinical investigations to compare the safety and efficacy of a racemate and its enantiomers. Examples of te basis for such regulation are drawn from historical situations (thalidomide, benoxaprofen) as well as currently marketed drugs (arylproionic acids, disopyramide, indacrinone).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010103
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  • 2
    Electronic Resource
    Electronic Resource
    Pharmacokinetic data of propranolol enantiomers in a comparative human study with (S)- and (R,S)-propranolol (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 10-13 
    Details
    ISSN: 0899-0042
    Keywords: (S)-, (R,S)-propranolol ; pharmacokinetic ; human study ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pharmacokinetics of (S)-propranolol were compared after the oral administration of a 40 mg dose of the pure enantiomer and an 80 mg dose of a racemic mixture of (R,S)-propranolol. The results of this study indicate that the bioavailability of (S)-propranolol, as expressed by the mean area uner the concentration-time curve (AUC) and maximum serum concentration, is lower after 40mg of the optically pure drug than after the racemic drug.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010105
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  • 3
    Electronic Resource
    Electronic Resource
    Stereocontrolled synthesis of peptide bond isosteres (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 89-91 
    Details
    ISSN: 0899-0042
    Keywords: asmmetric induction ; bacterial cell wall ; D-Ala-D-Ala ; dipeptide ; peptidoglycan ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absolute stereochemical control is employed in the synthesis of isosteres for dipeptide subunits 1; see Fig. (1) in which the amide linkage has been replaced by a trans carbon-caron double bond. The synthesis affords access to the four stereoisomers of 1 in which R and R' = CH3, including the isostere of D-alanine-d-alanine (D-ala-D-Ala), 2.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010116
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanisms of chiral recognition in xenobiotic metabolism and drug-receptor interactions (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 7-9 
    Details
    ISSN: 0899-0042
    Keywords: substrate enantioselectivity ; product enantioselectivity ; Michaelis-Menten analysis ; intrinsic activity ; potency ; receptor affinity ; efficacy ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010104
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  • 5
    Electronic Resource
    Electronic Resource
    Methiodide of the GABA antagonist (+)-bicuculline is levorotatory (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 178-179 
    Details
    ISSN: 0899-0042
    Keywords: CD spectra ; optical rotation ; phthalideisoquinoline base and salts ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The appearance of positive charge on the nitrogen moiety of phthalideisoquinoline alkaloids brings about a strong change in the intensities of CD Cotton effects. Hence the optical rotations of enantiomeric salts and their parent base of identical configuration are often of opposite sign. Thus, the name (+)-bicuculline-methiodide for the methiodide salt of (+)-bicuculline is false.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010214
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  • 6
    Electronic Resource
    Electronic Resource
    Stereoselectivity at muscarinic receptor subtypes: observations with the enantiomers of phenglutarimide (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 170-173 
    Details
    ISSN: 0899-0042
    Keywords: phenglutarimide enantiomers ; enantioselectivity ; antiparkinsonian drugs ; M1-selective antagonists ; rabbit vas deferens ; pirenzepine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The affinity of the enantiomers of phenglutarimide at three muscarinic receptor subtypes was examined in vitro using field-stimulated rabbit vas deferens (M1 receptors) and guinea pig atria (M2α receptors) and ileum (M2β receptors). Extremely high stereoselectivity was observed and higher affinities (up to 6000-fold) were found for the (+)-S-enantiomer. The stereoselectivity ratios were different at the three subtypes, and the stereochemical demands made by the muscarinic receptors were most stringent at M1 receptors. (+)-(S)-Phenglutarimide was found to be a potent M1-selective antagonist (pA2 at M1 = 8.53). Its receptor selectivity profile is qualitatively similar to that of pirenzepine. (-)-(R)-Phenglutarimide showed no comparable discriminatory properties.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010212
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  • 7
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of the enantiomers of terbutaline after repeated oral dosing with racemic terbutaline (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 174-177 
    Details
    ISSN: 0899-0042
    Keywords: pharmacokinetics ; terbutaline ; enantiomers ; human ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Terbutaline is a β2-agonist and administered as the racemic mixture. The pharmacokinetics of the separate enantiomers differ with respect to degree of absorption and clearance. In the present study, repeated doses of racemic terbutaline were given to six healthy volunteers. Plasma was analyzed for the concentrations of the two enantiomers. The observed plasma concentrations at steady state differed from those predicted from the values observed after single dose administration of the separate enantiomers. The difference between the observed and predicted values can be tentatively explained by a combined influence of (-)-terbutaline on the absorption of (+)-terbutaline and the influence of (+)-terbutaline on the elimination of (-)-terbutaline. The results have implications for the interpretation of effect/concentration studies with terbutaline, but do not affect the doses used in clinical practice.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010213
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  • 8
    Electronic Resource
    Electronic Resource
    Stereochemistry of tissue distribution of racemic propranolol in the dog (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 192-196 
    Details
    ISSN: 0899-0042
    Keywords: propranolol enantiomers ; enantiomers ; propranolol ; β-receptor-blocking drugs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Only limited information is available on the stereochemistry of the in vivo distribution of β-receptor-blocking drugs. In this study we determined the levels of the propranolol enantiomers in plasma, cerebrospinal fluid (CSF) and central nervous system (CNS), and peripheral tissues in the dog following an intravenous dose of a deuterium-labeled pseudoracemate. The appearance of the propranolol enantiomers in the CSF was rapid and nonstereoselective, with maximum concentrations reached at 15 min after dosing. The levels of the enantiomers in both CSF and plasma then declined in a parallel biphasic fashion, with a terminal t1/2 of about 125 min. Except for an early high CSF/plasma concentration ratio of 0.35, the CSF propranolol levels corresponded to the unbound concentration in plasma, CSF/plasma 0.20. All areas of the brain showed a similar uptake of propranolol, with a tissue concentration exceeding that in plasma about 10-fold during the terminal phase of elimination. The uptake of propranolol by peripheral tissues varied widely, ranging from a 50-fold accumulation by the lungs compared to plasma to no accumulation by adipose tissue. However, as for the CSF, there was no evidence of stereoselective uptake of propranolol by any CNS or peripheral tissue except for the liver. A significantly higher level of (+)- vs. (-)-propranolol in liver tissue presumably was a reflection of stereoselective hepatic metabolism of (-)-propranolol by this tissue. The slight stereoselectivity in plasma binding of propranolol known to exist in the dog had no significant influence on tissue or CSF distribution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010303
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  • 9
    Electronic Resource
    Electronic Resource
    The development of concepts of chiral discrimination (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 183-191 
    Details
    ISSN: 0899-0042
    Keywords: enantiomorphism ; dissymmetry ; chirality ; enantioselectivity ; diastereoselectivity ; steric complementarity ; asymmetric induction ; three-point contact ; circularly polarized radiation ; circular dichroism ; parity nonconservation ; electroweak interaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pasteur's conjecture (1860) that biomolecular homochirality arose from a chiral natural force as yet inaccessible in the laboratory was supplanted by Fischer's (1894) “key and lock” hypothesis of stereoselection in enantiomer to diastereomer conversions, whether in the laboratory or in living organisms. Elaborations of the “key and lock” hypothesis by Haldane (1930) and Pauling (1948) have been illustrated and supported with modification by X-ray diffraction crystal structures of enzyme-substrate complexes over the past quarter century.Two types of mechanism for the product diastereoselectivity in the reactions of an enantiomer with an achiral reagent, early proposed, have recent support: one proposes a quasidiastereomeric structure for the enantiomer attacked in the ground state, the other for the corresponding transition state of the reaction. Approaches to the differential biological activity of two enantiomers postulate either the complete binding of each isomer to a chiral receptor site, resulting in diastereomeric complexes with inequivalent bioactivities, or the differential binding of the two isomers to a set of three sites, with which only one isomer is sterically congruent.Biochemical homochirality, based on the chiral stereoselectivity of both biosynthetic and metabolic reactions, derives from the evolutionary pressure for a progressive enhancement of the kinetic efficiency and economy of those reactions. Recently Pasteur has been vindicated in part, and the problem of the original prebiotic enantiomeric excess left outstanding by Fischer has been solved. The unification of the electromagnetic with the weak interaction provided a universal chiral natural force, the electroweak interaction, which favours the chiral series selected during the course of biochemical evolution, both the D-sugars and the L-amino acids.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010302
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  • 10
    Electronic Resource
    Electronic Resource
    Stereochemical influences upon the opioid ligand activities of 4-alkyl-4-arylpiperidine derivatives (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 202-208 
    Details
    ISSN: 0899-0042
    Keywords: opioid ligand ; 4-arylpiperidines ; conformation, NMR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and stereochemistry (configuration and preferred solute conformation) of some 4-alkyl (methyl, n-propyl, isobutyl)-4-(3-hydrxyphenyl)-1-methylpiperidines and corresponding 3-methyl diastereoisomeric pairs are reported, together with their in vivo and in vitro activities as opioid ligands. All potent agonists exhibit a preference for axial 4-aryl chair conformations when protonated, and stereochemical analogies with rigid opioids of the benzomorphan class are discussed. Antagonist properties are found in compounds with preference for equatorial 4-aryl chairs, notably the cis 3,4-dimethyl derivative.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010305
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  • 11
    Electronic Resource
    Electronic Resource
    Species differences in the chirality of the carbonyl reduction of [14C] fenofibrate in laboratory animals and humans (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 197-201 
    Details
    ISSN: 0899-0042
    Keywords: fenofibrate ; chiral reduction ; species differences ; prochiral to chiral transformation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The prochiral carbonyl group of fenofibrate (isopropyl 2-[4-(4-chlorobenzoyl)phenoxy]-2-methyl propionate) is reduced during its metabolism giving rise to a chiral secondary alcohol, “reduced fenofibric acid.” Chiral and diastereomeric HPLC methods have been developed for the determination of its enantiomeric composition and these have been applied to the measurement of the “reduced fenofibric acid” enantiomers in urine of rats, guinea pigs, dogs, and human volunteers given [14C]fenofibrate. In the three animal species, the reduction is markedly enantioselective for the (-)-isomer, the enantiomeric ratios (-/ +) being 95:5. This was not due to differences in the excretion of the enantiomers, since when racemic “reduced fenofibric acid” was given to rats it was recovered in the urine with the same enantiomeric composition as the dose form. In humans the ratio was 52:48 showing the lack of stereoselectivity of reduction in this species.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010304
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  • 12
    Electronic Resource
    Electronic Resource
    Joining hands (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 1-1 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010102
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  • 13
    Electronic Resource
    Electronic Resource
    Pharmacologic implications of α-adrenocreceptor interactive parameters for epinephrine enantiomers in the rat vas deferens (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 14-19 
    Details
    ISSN: 0899-0042
    Keywords: affinity ; efficacy ; dissociation ; constants ; steroselectivity ; entropy ; enthalpy ; receptor ; interaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After alkylation of a fraction of the total α-adrenoreceptors by phenoxybenzamine in rat vas deferens, the dissociation constants of (-)- and (+)-epinephrine in functional studies were 7 × 10-7 M and 2 × 10-5 M, respectively. In the adrenoreceptor-containing tissue fraction, when 3H-labeled WB4101 was used as the interacting ligand, for each enantiomer who affinity sites were found. Only the low-affinity dissociation consant for each isomer correlates with the constant obtained from the functional studies. If the change in Gibb's free energy. ΔG°, is calculated from the low-affinity binding constants, the values -8.1 and -6.2 kcal/mol for (-)- and (+)-isomer, respectively, are obained. The small difference in the value between isomers forms a hydrogen bond with the receptor. The interaction of epinephrine with this receptor appears to be driven largely by the entropy of the drug-receptor interaction with only a small nonsteroselective contribution from the enthalpy of ineraction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010106
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  • 14
    Electronic Resource
    Electronic Resource
    Preparation of chiral statonary phase from an α-amino phosphonate (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 57-62 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; α-amino phosphonate ; chromatographic separation of enantiomers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A chiral statonary phase (CSP) derived from an N-(3,5-dinitrobenzoyl)-α-aminobenzylphosphonate has been prepared and evaluated for its utility in the direct separation of enantiomers. This CSP, 2, is structurally related to earlier N-(3,5-dinitrobenzoyl)-α-acids acid-derived phases (e.g., CSP 1), but the mode of attachment to the support is different. In scope; CSP 2 is qualitaively similar to CSP 1. However, it differs quantitatively from CSP 1, showing either greater or lesser selectivity for different pairs of enantiomers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010111
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  • 15
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010101
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  • 16
    Electronic Resource
    Electronic Resource
    The stereochemical resolution of enantiomeric free and derivatized amino acids using and hplc chiral stationary phase based on immobilized α-chymotrypsin: Ciral separation due to solue structure or enzyme activity (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 38-44 
    Details
    ISSN: 0899-0042
    Keywords: column liquid chromatography ; chiral separations ; chymotrypsin on silica ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemical separation of free and derivatized amino acids on active α-chymotrypsin bonded to silica is governed by two mechanisms based on the structure of the solutes or on the enzymatic activity of the enzyme. Te deactivation of the hydrolytically active site of the enzyme demonstrated that a significant portion of the retention on this support is due to hydrophobic interactions at other sites. These sites appear to be stereoselective for the ester derivatives of amino acids but not for the other studied solutes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010109
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  • 17
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010201
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  • 18
    Electronic Resource
    Electronic Resource
    Implications of chirality and geometric isomerism in some psychoactive drugs and their metabolites (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 99-120 
    Details
    ISSN: 0899-0042
    Keywords: asymmetry ; enantiomers ; geometric isomers ; (+)- (-)-isomers ; D- and L-isomers ; R- and S-isomers ; Z- and E-isomers ; drug metabolism ; stereoselectivity and stereospecificity in drug action ; stereoselectivity and stereospecificity in drug metabolism ; psychotropic drugs ; stimulants ; antidepressants ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many drugs contain a chiral centre, or such a centre is introduced during metabolism of the drug in man and in animals. If a single chiral centre is present, the drug will normally exist as a mixture of two enantiomers, of which one may have quite different pharmacologic and/or toxic effects than the other. Chiral drugs that are used in psychiatry, and some other pharmacologically related drugs are identified, and the implications of the presence of one or two chiral centres in these drugs are discussed. Differences in pharmacologic properties of drug and metabolite enantiomers are identified and discussed. Also reviewed are the properties of some drugs used in psychiatry that both are chiral and display geometric isomerism.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010204
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  • 19
    Electronic Resource
    Electronic Resource
    Optical enrichment of dansyl-rac-amino acids by formation of crystalline inclusion complexes with cyclodextrins (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 137-141 
    Details
    ISSN: 0899-0042
    Keywords: resolution by crystallization ; racemic mixture ; dansyl-D-leucine ; dansyl-L-leucine ; dansyl-D-norleucine ; dansyl-L-norleucine ; dansyl-D-phenylalanine ; dansyl-L-phenylalanine ; β-cyclodextrin ; γ-cyclodextrin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical enrichment from racemic dansyl-leucine, dansyl-norleucine, and dansyl-phenylalanine with both β- and γ-cyclodextrins in water is reported. Initial crystallization yielded the dansyl-L-leucine isomer complexed in excess with β-cyclodextrin with an optical purity of 62-78% depending on experimental conditions. The optical purities obtained for L-norleucine and L-phenylalanine were 71 and 64%, respectively. The optical purity can be increased with continued recrystallization. The dansyl-D-leucine isomer was obtained in the mother liquor with an optical purity of 54-93% depending on experimental conditions. The optical purities obtained for D-norleucine and D-phenylalanine were 72 and 58%. The optical purity of the isomer depended on the molar ratio of host:guest and the pH value of the solution. Optimum enrichment of both enantiomers was achieved with host:guest ratios of 2 : 1 and 3 : 1. Although maximum crystalline yield of the dansyl-leucine/CD inclusion complex was obtained at a pH of 3.5, optical purity of both enantiomers was less than that obtained at other pHs. The influence of the molar ratio of host:guest and the pH value of the solution are discussed. This method is suitable for large-scale enantiomeric separations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010207
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  • 20
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010301
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  • 21
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010401
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  • 22
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    St. Mary's discussion forum: “Racemates and enantiomers: Scientific and regulatory aspects” (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 249-250 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010402
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  • 23
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    The interaction of the enantiomers of carvedilol with α1- and β1-adrenoceptors (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 265-270 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoselectivity of carvedilol, a novel β-adrenoceptor antagonist and vasodilator with one asymmetric carbon atom, was examined at α1- and β1-adrenoceptors in vitro and in vivo. (-)-(S)-Carvedilol is a potent, competitive antagonist of the β1-adrenoceptor-mediated positive chronotropic response to isoproterenol in guinea pig atrium, with a dissociation constant (KB) of 0.4 nM. (+)-(R)-Carvedilol was more than 100-fold less potent than the (-)-S-enantiomer as an antagonist of β;1-andrenoceptors, having a KB of approximately 45 nM. Consistent with these findings (-)-(S)-carvedilol (0.1 mg/kg, i.v.) produced a 25-fold rightward shift in the β1-adrenoceptor-mediated positive chronotropic response to isoproterenol in pithed rats, whereas the (+)-R-enantiomer had no β1-adrenoceptor blocking activity in vivo at this dose. In contrast to the marked degree of stereoselectivity observed at βl1-adrenoceptors, both (-)-(S)- and (+)-(R)-carvedilol produced equal antagonism of the α1----adrenoceptor-mediated vasoconstrictor response to norepinephrine in rabbit aorta, with KB values of 14 and 16 nM, respectively. Furthermore, in the pithed rat, the α1-adrenoceptor-mediated pressor dose-response curve to cirazoline was shifted approximately 6-fold to the right by both the (+)-R- and (-)-S-enantiomers of carvedilol at a dose of 1 mg/kg, i.v. In anesthetized spontaneously hypertensive rats, (-)-(S)-carvedilol was 6-fold more potent as an antihypertensive than (+)-(R)-carvedilol. The vasodilator and acute antihypertensive activity of carvedilol results from α1-andrenoceptor blockade produced by both enantiomers, and the concomitant β1-adrenoceptor blockade produced by the (-)-S-enantiomer, which prevents reflex tachycardia that can offset the antihypertensive response, leading to greater overall antihypertensive potency of (-)-(S)-carvedilol relative to the (+)-R-enantiomer. These data also suggest that distinct regions of the carvedilol molecule are responsible for blocking α1- and β1-adrenoceptors, with β1-adrenoceptor blockade resulting from an area of the molecule containing the asymmetric carbon atom, specifically the carbazolyloxy propanolamine moiety, and α1-adrenoceptor blockade resulting from a part of the molecule that does not contain the asymmetric carbon atom, most likely the phenoxyethylamine moiety.
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    Crystal structure and absolute configuration of (+)546-[copy4Cl2]HDBT: An example of torsional isomerism (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 284-292 
    Details
    ISSN: 0899-0042
    Keywords: absolute configuration ; crystal structure ; resolution ; solid-state circular dichroism ; torsional isomerism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure and absolute configuration of the (-)589-dibenzoylmonohydrogentartrate salt of the cation [Co(pyridine)4Cl2]+ have been determined from a three-dimensional X-ray analysis. Single crystals were grown from dimethylsulfoxide: space group P212121, Z = 4, and cell dimensions a = 21.463(4), b = 23.112(3), and c = 7.490(1) Å. Full-matrix least-squares refinement on F converged at R = 0.075, 196 variables and 2029 observations. The cation has pseudotetragonal coordinate geometry, with axial Cl and equatorial N atoms. The dihedral angles between the pyridine ligands and the equatorial plane are 47(1), 39(1), 50(1), and 45(1)° and torsional isomerism is responsible for the solid-state chiroptical properties of the cation. The preferential crystallization of the P atropisomer of the cation is attributed to a general electrostatic attraction between cation and anion.
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    Announcements (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 94-95 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010118
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    Response to letter to the editor (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 98-98 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010203
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    Determination of terbutaline enantiomers in biological samples using liquid chromatography with coupled columns (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 20-26 
    Details
    ISSN: 0899-0042
    Keywords: terutaline ; enantiomers ; determination ; liquid ; chromatography ; coupled columns ; cyclodextrin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The purpose of this work was to develop and validate a method for the separation and determination of the enantiomers of terbutaline in plasma and intestinal juice. Terbutaline was extracted from plasma and intestinal juice by liquid-solid extraction on small C18 cartridges. The extract was then analyzed by coupled column liquid chromatography with amperometric detecton. For ciral separation a β-cyclodextrin phase was used.The within-day variation (Cv) on spiked plasma samples was in the rane 0.8-6.4% at 3.8-33.8 nmol/liter for the (-)-enantiomer, and 2.6-23.0% at 1.3-11.3 nmol/liter for the (+)-enantiomer. The between-day variation on spiked plasma samples was 5.5% at 10.7 nmol/liter and 13.6% at 4.3 nmol/liter for the (-)- and (+)-enantiomers, respectively. The within-day variation for inestinal juice was i the range 0.7-1.5% at 5.6-30.0 μmol/liter for the (+)-enantiomer.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530010107
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    Letter to the editor (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 97-97 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010202
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  • 29
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    Stereoselective sulfation of terbutaline by the rat liver cytosol: evaluation of experimental approaches (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 121-126 
    Details
    ISSN: 0899-0042
    Keywords: stereoselective metabolism ; sulfate conjugation ; in vitro sulfation ; sympathomimetic amines ; chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Little is known about the stereochemistry of sulfation of chiral phenolic drugs. In this study we examined several in vitro approaches to this question, using (+)-, (-)-, or (±)-terbutaline as the substrate and the rat liver cytosol as the phenolsulfotransferase enzyme source. The cosubstrate PAPS was either generated by the cytosol from inorganic sulfate and ATP or added to the cytosol. The intact sulfate conjugates formed were determined by HPLC. Using the PAPS generating system, which is best suited for the production of relatively large quantities of sulfate conjugates, with the individual enantiomers as substrates, (+)-terbutaline was conjugated to a much greater extent than (-)-terbutaline; the (+)/(-)-enantiomer ratio was 7.3 ± 0.3 (mean ± SE). When (±)-terbutaline was the substrate and chiral derivatization was employed to separate the sulfate enantiomers formed, a similar (+)/(-)-enantiomer ratio of 7.9 ± 0.2 was obtained. With PAP35S added to the cytosol, an approach best suited for kinetic studies, the substrate concentration dependence of sulfation could be determined. The Km app for this reaction was identical for (+)- and (-)-terbutaline. However, the Vmax app was 8.1 ± 0.4 times greater for (+)-terbutaline. This study for the first time shows enantioselectivity in sulfation of a chiral phenolic drug. The experimental approaches used should be valuable for human studies of stereoselectiven sulfation of terbutaline and other chiral drugs.
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    Cytochrome P-450-catalyzed asymmetric epoxidation of simple prochiral and chiral aliphatic alkenes: species dependence and effect of enzyme induction on enantioselective oxirane formation (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 127-136 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective epoxidation ; cytochrome P-450-dependent monooxygenases ; species dependence of microsomal epoxidation ; product enantioselectivity ; substrate enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselectivity of the in vitro conversion of simple prochiral and chiral aliphatic alkenes into oxiranes by liver microsomes of untreated or induced (phenobarbital) rats, of untreated or induced (phenobarbital, benzo[α] pyrene) mice, and of humans was determined by complexation gas chromatography. The enantiomeric excess (ee) of the epoxides extends from 0 (trimethyloxirane) to 50% (ethyloxirane). The configuration (R or S) of the enantiomers formed in excess is consistent for homologous oxiranes but is species dependent and in some cases influenced by enzyme induction. Enantioselectivity differences of aliphatic alkene epoxidation by human liver microsomes of four individuals are negligible.
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    Optical resolution of some biologically active compounds by chiral liquid chromatography on BSA-silica (resolvosil) columns (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 154-160 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; chiral discrimination ; drugs ; hydrophobic interaction ; biopolymers ; elution order ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical resolution on the analytical scale of a number of racemic pharmaceuticals and some other biologically active compounds has been studied using immobilized bovine serum albumin (BSA) as the stationary phase. For some of the compounds the elution order was determined by the use of optically enriched fractions obtained from a preceding passage of a sample through a preparative column containing microcrystalline triacetylcellulose (MCTA). The reversal in the sign of optical rotation shown in the polarimetric elution profile from the latter, combined with the integrated peak area ratio obtained on resolution on the analytical column, gave directly the order of elution. For one of the benzothiadiazines studied (bendroflumethiazide), increasing the pH of the mobile phase produced opposite effects on the retention of the two enantiomers, leading to a large effect on the separation factor. For many of the compounds studied, high separation factors (α 〉 2) could be achieved.
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    URL: http://dx.doi.org/10.1002/chir.530010209
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    Direct separation of albendazole sulfoxide enantiomers by liquid chromatography on a chiral column deriving from (S)-N-(3,5-dinitrobenzoyl)tyrosine: application to enantiomeric assays on plasma samples (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 142-153 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separations ; chiral stationary phase ; Pirkle-type phases ; HPLC ; anthelmintics ; benzimidazole sulfoxides ; albendazole ; fenbendazole ; oxfendazole ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct enantiomeric resolution of albendazole sulfoxide (SOABZ), an anthelmintic drug belonging to the benzimidazole class, is reported on a chiral stationary phase (CSP) synthesized by covalent binding of (S)-N-(3,5-dinitrobenzoyl)tyrosine-O-(2-propen-1-yl) methyl ester on a γ-mercaptopropylsilanized silica gel. A comparison with the resolution achieved on commercially available Pirkle-type CSPs obtained from N-(3,5-dinitrobenzoyl) derivatives of (R)-phenyglycine or (S)-phenylalanine is described. Some structurally related chiral sulfoxides including oxfendazole (SOFBZ) are also studied. Optimization of the mobile phase nature and composition is investigated showing that a hexane-dioxane-ethanol ternary mixture affords an almost baseline resolution (Rs = 1.25); however, in this case, albendazole sulfone (SO2ABZ) is eluted between the two sulfoxide enantiomers; accordingly, a hexane-ethanol mobile phase would be preferred for biological samples containing both metabolites. The influence of temperature on the resolution is depicted with a hexane-ethanol mobile phase. Finally, application to the enantiomeric assays of SOABZ in plasmatic extracts of rat, sheep, bovin, and man after oral administration of albendazole (sulfoxidized to SOABZ and SO2ABZ) is reported. Some distortions in the enantiomeric ratios are evidenced depending on the species.
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    A vivid model of chiral recognition (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 167-169 
    Details
    ISSN: 0899-0042
    Keywords: enantioselectivity ; three-point model ; chiral receptors ; chiral separations ; didactic model ; elusion of the three-point model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hands can be used to demonstrate the three-point model of chiral recognition. The points of attachment are thumb, forefinger, and middle finger. This vivid model has the advantages of simplicity, perspicuity, and availability at any time, although two persons are necessary. It can be shown that two interactions are not sufficient for chiral recognition but that three attractive or two attractive and one repulsive attraction are needed. It can also be used to explain some possibilities of weakening or elusion of the three-point model.
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    URL: http://dx.doi.org/10.1002/chir.530010211
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    Resolution of some β-hydroxyphenethylamines as N-(3,5-dinitrobenzoyl) amides on chiral stationary phases derived from cinchona alkaloids (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 161-166 
    Details
    ISSN: 0899-0042
    Keywords: chromatography ; chirality ; chiral recognition ; β-aminoalcohols ; stereochemistry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three chiral stationary phases, obtained by derivatizing γ-mercaptopropylsilanized silica gel with quinine, quinidine, and cinchonidine, have been employed in the resolution of N-acyl derivatives of β-hydroxyphenethylamines. The use of circular dichroism for detection and NMR analysis of analyte-selector mixtures provides an experimental basis for preliminary assignment of a recognition mechanism.
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    Announcements (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 178-179 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010215
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    First announcement and call for papers (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 246-248 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/chir.530010312
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    Direct chromatographic separation of 2-arylpropionic acid enantiomers using tris(3,5-dimethylphenylcarbamate)s of cellulose and amylose as chiral stationary phases (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 239-242 
    Details
    ISSN: 0899-0042
    Keywords: optical resolution ; HPLC ; chromatography ; antiinflammatory drug ; ibuprofen ; ketoprofen ; flurbiprofen ; tiaprofenic acid ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct optical resolution of antiinflammatory drugs such as ibuprofen, ketoprofen, flurbiprofen, and tiaprofenic acid were attempted by high-performance liquid chromatography using tris(3,5-dimethylphenylcarbamate)s of cellulose and amylose as chiral stationary phases. Although ibuprofen was not sufficiently resolved, the other three 2-arylpropionic acids were completely resolved by amylose tris(3,5-dimethylphenylcarbamate). Ibuprofen was resolved as anilide derivative.
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    Das einfachste Biformazan: 1,1′,5,5′-Tetraphenyl-3,3′-biformazan (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1226-1234 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Simpliest Biformazan: 1,1′,5,5′-Tetraphenyl-3,3′-biformazanThe synthesis and the properties of the biformazan 9 are reported. Dehydrogenation of 9 yields the betain 20, which like the salt 21 represents the middle oxidation state between the biformazan 9 and the bis(tetrazolium salt) 22.
    Notes: Darstellung und Eigenschaften des Biformazans 9 werden beschrieben. Die Dehydrierung von 9 ergibt das Betain 20, das wie das Salz 21 der mittleren Oxidationsstufe zwischen dem Biformazan 9 und dem Bis(tetrazoliumsalz) 22 entspricht.
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    Beiträge zur Chemie des Bors, CII. Synthese und Reaktionen von 1-Stanna-4-bora-2,5-cyclohexadienen (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1235-1244 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Boron, CII. Synthesis and Reactions of 1-Stanna-4-bora-2,5-cyclohexadienesHydrostannation of (dialkylamino)dialkinylboranes 1 with dimethylstannane yields 1,1-dimethyl-1-stanna-4-bora-2,5-cyclohexadienes 2. Additional 4-amino derivatives are accessible via trans-amination reactions. Solvolysis of the amino derivatives by alcohols leads to alkoxy derivatives 3. These are alkylated by aluminium alkyls or tert-butyllithium to 4-alkyl-1,1-dimethyl-1-stanna-4-boracyclohexadienes 5. A considerable difference in the chemical behaviour of the 1,1-dimethyl-and the 1,1,2,6-tetramethyl derivatives has been observed.
    Notes: Die Hydrostannierung von (Dialkylamino)dialkinylboranen 1 mit Dimethylstannan führt zu 1,1-Dimethyl-1-stanna-4-bora-2,5-cyclohexadienen 2. Über Transaminierung sind weitere 4-Amino-Derivate zugänglich. Die Solvolyse der Amino-Derivate mit Alkoholen liefert die Alkoxyderivate 3, die mit Aluminiumalkylen bzw. mit tert-Butyllithium zu 4-Alkyl-1,1-dimethyl-1-stanna-4-boracyclohexadienen 5 alkyliert werden. Zwischen den 1,1-Dimethyl- und den 1,1,2,6-Tetramethyl-Derivaten bestehen beträchtliche Unterschiede im chemischen Verhalten.
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    Sensibilisierte Photooxygenierung von Silylenolethern cyclischer Ketone (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1245-1263 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sensitized Photooxygenation of Silyl Enol Ethers of Cyclic Ketonesα,β-Unsaturated and α-hydroxy ketones are accessible in prototropic ene-reactions with singlet oxygen by sensitized photooxygenation of cyclic silyl enol ethers and subsequent reduction and solvolysis. In a competing silatropic ene-reaction α-silyloxyketones are formed. Formation of different products depends on ring size, configuration and substitution. At C-6 chirally substituted 2-cyclohexenones are synthesized for the first time by sensitized photooxygenation of chiral silyl enol ethers of optically active starting ketones.
    Notes: Die sensibilisierte Photooxygenierung cyclischer Silylenolether liefert durch prototrope En-Reaktion mit Singulett-Sauerstoff nach Reduktion und Solvolyse α,β-ungesättigte Ketone sowie α-Hydroxyketone. Durch eine konkurrierende silatrope En-Reaktion werden α-Silyloxyketone gebildet. Die Produktverteilung wurde in Abhängigkeit von Ringgröße, Konfiguration und Substitution untersucht. Ausgehend von chiralen Silylenolethern optisch aktiver Ausgangsketone wurden erstmals an C-6 chiral alkylsubstituierte 2-Cyclohexenone synthetisiert.
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    Thermische Umlagerungen von 8-Methoxybicyclo[5.1.0]octa-2,4-dien und 8-Methoxybicyclo[5.1.0]oct-2-en (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1272-1279 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermal Rearrangements of 8-Methoxybicyclo[5.1.0]octa-2,4-diene and 8-Methoxybicyclo[5.1.0]oct-2-eneThe equilibria 2x ⇄ 3e and 9x ⇄ 11 of the title compounds reveal a slight influence of methoxy substituents on the stability of cyclopropane rings. Reactions which involve the distal cyclopropane bond  -  the butadienylcyclopropane rearrangement of 2 and the homo-1,5-H shift of 9  -  are but modestly accelerated by methoxy groups. The vinylcyclopropane rearrangement 9x → 10 confirms the strong methoxy effect on proximal cyclopropane bonds.
    Notes: Die Gleichgewichte 2x ⇄ 3e und 9x ⇄ 11 der Titelverbindungen zeigen einen geringen Einfluß von Methoxy-Substituenten auf die Stabilität des Cyclopropanrings. Reaktionen unter Beteiligung der gegenüberliegenden Cyclopropan-Bindung  -  die Butadienylcyclopropan-Umlagerung von 2 und die Homo-1,5-H-Verschiebung von 9  -  werden durch Methoxygruppen nur mäßig beschleunigt. Die Vinylcyclopropan-Umlagerung 9x → 10 bestätigt den starken Methoxy-Effekt auf benachbarte Cyclopropan-Bindungen.
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    Beiträge zur Chemie des Phosphors, 88. 1,2,3-Triphenyl-1,3-bis(trimethylsilyl)triphosphan (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1264-1271 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Phosphorus, 88. 1,2,3-Triphenyl-1,3-bis(trimethylsilyl)triphosphaneThe reaction of 1,3-dipotassium 1,2,3-triphenyltriphosphide, K2 (PPh)3, with chlorotrimethyl-silane yields the hitherto unknown title compound Me3Si(Ph)P—P(Ph)—P(Ph)SiMe3 (1), which is remarkably stable against disproportionation reactions. In solution it forms the three diastereomers 1a (erythro/erythro), 1b (erythro/threo), and 1c (threo/threo) in a ratio of about 8:3:1, between which a dynamic equilibrium exists due to pyramidal inversion at the P-atoms. The correlation between the 31P-NMR-spectroscopically observed spin systems and the diastereomers 1a-c results from the significant dependence of the 1JPP-coupling constants on dihedral angles. The preferred trans arrangement of the bulky SiMe3- and P(Ph)SiMe3 groups at adjacent P-atoms leads to a trans-conformation of the lone electron pairs in the erythro- and to a gauche-conformation in the threo-configuration.
    Notes: Die Reaktion von 1,3-Dikalium-1,2,3-triphenyltriphosphid, K2(PPh)3, mit Chlortrimethylsilan ergibt in guter Ausbeute die bislang unbekannte Titelverbindung Me3Si(Ph)P—P(Ph)—P(Ph)SiMe3 (1), die gegenüber Disproportionierungsreaktionen bemerkenswert beständig ist. Sie bildet in Lösung die drei Diastereomeren 1a (erythro/erythro), 1b (erythro/threo) und 1c (threo/threo) im Verhältnis von etwa 8:3:1, die infolge pyramidaler Inversion der P-Atome in einem dynamischen Gleichgewicht miteinander stehen. Die Korrelation zwischen den 31P-NMR-spektroskopisch beobachteten Spinsystemen und den Diastereomeren 1a-c ergibt sich aufgrund der signifikanten Torsionswinkelabhängigkeit der 1JPP-Kopplungskonstanten. Die bevorzugte trans-Anordnung der großvolumigen SiMe3- und P(Ph)SiMe3-Reste an benachbarten P-Atomen führt bei erythro-Konfiguration zu einer trans- und bei threo-Konfiguration zu einer gauche-Konformation der freien Elektronenpaare.
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    Anorganische Cyclopentan-Varianten: Organometall-Arsen-Fünfringe mit Fe—Co—As—Fe—As- und Mn—As—As—Mn—As-Gerüst (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1280-1289 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Inorganic Cyclopentane Variants: Organometal-Arsenic Five-Membered Rings with Fe—Co—As—Fe—As and Mn—As—As—Mn—As BackbonesBy unusual reactions the polynuclear complexes Fe2CoCp3(CO)3(AsMe2)2 (1) and Mn2(CO)7Hal-(AsMe2)3 (2, Hal=Cl, Br) were formed in moderate to good yields. Both were identified crystallo-graphically as inorganic five-membered ring systems. 1 has a Fe—Co—As—Fe—As-, 2 has a Mn—As—As—Mn—As backbone. The geometry of 1 resembles the envelope conformation, that of 2 resembles the half-chair conformation of cyclopentane.
    Notes: Durch ungewöhnliche Reaktionen entstanden in mäßigen bis guten Ausbeuten die Mehrkernkomplexe Fe2CoCp3(CO)3(AsMe2)2 (1) und Mn2(CO)7Hal(AsMe2)3 (2, Hal=Cl, Br). Beide wurden kristallographisch als anorganische Fünfring-Systeme identifiziert. 1 hat ein Fe—Co—As—Fe—As-, 2 ein Mn—As—As—Mn—As-Gerüst. Die Geometrie von 1 ähnelt der „Briefumschlag“-Konformation, die von 2 der „Halbsessel“-Konformation des Cyclopentans.
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    Doppelt metalliertes Methanol. Alkohol-d1- und -d3 -Reagenzien (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1290-1303 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Doubly Metalated Methanol.  -  Alcohol d1-and d3-ReagentsThe nucleophilic counterpart of the electrophilic hydroxymethylating protonated formaldehyde B is the hypothetical tautomer A, R=H, of methoxide. Experiments are described in which the generation of doubly metalated methanol C (= formaldehyde ketyl dianion) and its use as methanol d1-reagent are attempted. Treatment of stannylated methanol 1 with two equivalents of butyllithium furnishes a pentane-soluble reagent which hydroxymethylates electrophilic centers in moderate yields (umpolung of the formaldehyde a1-reactivity), see eq. (1) and table 3. Attempted isolation, 1H- and 13C-NMR measurements, and careful product analysis of the reaction with benzaldehyde (scheme 1 and table 2) support the view that the new reagent is actually not free lithium lithio-methoxide (2) but a tin derivative, see for instance 9 in eq. (2).  -  The O-silylated derivative 18 (=A, R=SiMe3) is likewise generated by Sn-Li-transmetallation, but cannot be trapped externally by electrophiles due to rapid Wittig rearrangement (→ 19 → 20). The readily accessible dilithio derivatives 21a and 23a can be employed as direct propanol and allyl alcohol d3-reagents, respectively.
    Notes: Das nucleophile Pendant zum elektrophilen Hydroxymethylierungsmittel B, dem protonierten Formaldehyd, ist das fiktive Methanolat-Tautomere A, R=H. Es werden Versuche zur Erzeugung des doppelt metallierten Methanols C (= Formaldehyd-Ketyldianion-Derivat) und dessen Verwendung als Methanol-d1-Reagenz beschrieben. Durch Umsetzung des stannylierten Methanols 1 mit zwei Äquivalenten Butyllithium erhält man ein pentanlösliches Reagenz, welches elektrophile Zentren in mäßigen Ausbeuten hydroxymethyliert (Umpolung der Formaldehydreaktivität), Gl. (1) und Tab. 3. Isolierungsversuche, 1H- und 13C-NMR-Messungen sowie sorgfältige Produktanalyse der Reaktion mit Benzaldehyd (Schema 1 und Tab. 2) stützen die Hypothese, daß das erzeugte Reagenz nicht das freie Lithium-lithiomethanolat (2), sondern ein Sn-Derivat, z. B. 9 in Gl. (2) sein dürfte.  -  Das ebenfalls durch Sn/Li-Transmetallierung erzeugte O-Silylderivat 18 [=A, R=Si(CH3)3] läßt sich wegen zu schneller Wittig-Umlagerung (→ 19 → 20) nicht extern mit Elektrophilen abfangen, während die leicht zugänglichen Dilithiumderivate 21a und 23a als direkte Propanol- bzw. Allylalkohol-d3-Reagenzien fungieren.
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    Reaktionen koordinierter Liganden, VIII. Synthese, Reaktivität und Struktur von Molybdän-und Nickelcarbonyl-Komplexen des 1,3-Bis(phenylphosphino)propans, PhPH—CH2CH2CH2—PPhH (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1343-1355 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Coordinated Ligands, VIII. Synthesis, Reactivity, and Structure of Molybdenum- and Nickel Carbonyl Complexes of 1,3-Bis(phenylphosphino)propane1,3-Bis(phenylphosphino)propane reacts with Ni(CO)4, C7H8Mo(CO)4, and Mo(CO)6 to produce complexes of the type (CO)nM(PhPH—C3H6—PPhH) (n = 4, M=Mo; n = 2, M=Ni) and oligomers thereof. These compounds were also obtained by the reaction of phosphido complexes (CO)nM(PhPHM′)2 (n = 4, M=Mo, M′=Li; n = 2, M=Ni, M′=Li, Na) with 1,3-dibromopropane. The complexes (CO)nM(PhPH—C3H6—PPhH) may be deprotonated with methyllithium. The reactions of the phosphido complexes thus obtained are discussed. From the meso-form of (CO)2Ni(PhPH—C3H6—PPhH), which crystallizes in the space group Cmc21, an x-ray structure analysis has been performed.
    Notes: 1,3-Bis(phenylphosphino)propan reagiert mit Ni(CO)4, C7H8Mo(CO)4 und Mo(CO)6 unter Bildung von Komplexen des Typs (CO)nM(PhPH—C3H6—PPhH) (n = 4, M=Mo; n = 2, M = Ni) und deren Oligomeren. Diese Verbindungen werden auch bei Umsetzung von Phosphidokomplexen (CO)nM(PhPHM′)2 (n = 4, M=Mo, M′=Li; n = 2, M=Ni, M′=Li, Na) mit 1,3-Dibrompropan erhalten. Die Komplexe (CO)nM(PhPH—C3H6—PPhH) lassen sich mit Methyllithium deprotonieren. Über Reaktionen der dabei gebildeten Phosphidokomplexe wird berichtet.  -  Von der Mesoform von (CO)2Ni(PhPH—C3H6—PPhH) (1), das in der Raumgruppe Cmc21 kristallisiert, wurde eine Röntgenstrukturanalyse durchgeführt.
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    Darstellung, Eigenschaften und Struktur von Di-μ-halogeno- bis[dicarbonyl(tri-tert-butylphosphan)ruthenium(I)](Ru—Ru) (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1385-1393 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Properties, and Structure of Di-μ-halogeno-bis[dicarbonyl(tri-tert- butylphosphane)-ruthenium(I)](Ru—Ru)Ruthenium trichloride trihydrate (1) reacts with carbon monoxide and tri-tert-butylphosphane (2) in 2-methoxyethanol to form di-μ-chloro-bis[dicarbonyl(tri-tert- butylphosphane)ruthenium(I)]-(Ru—Ru) (3). The corresponding bromo- (5), and iodo derivatives (6) are formed either from 3 by halogen exchange using LiBr or Nal or by the reaction of di-μ-halogeno-bis[tricarbonylhalogeno-ruthenium(II)] with 2. The crystal structure of 5, has been determined from single crystal X-ray data. The compound crystallizes with 4 molecules in a unit cell of symmetry P21/a in the monoclinic system.
    Notes: Rutheniumtrichlorid-trihydrat (I) reagiert mit Kohlenmonoxid und Tri-tert-butylphosphan (2) in 2-Methoxyethanol unter Bildung von Di-μ-chloro-bis[dicarbonyl(tri-tert- butylphosphan)ruthenium(I)](Ru—Ru) (3). Die entsprechenden Brom- (5) und Iod-Derivate (6) entstehen entweder aus 3 durch Halogenaustausch mittels LiBr oder NaI oder durch Umsetzung von Di-μ-halogeno-bis[tricarbonylhalogeno-ruthenium(II)] mit 2. Die Kristallstruktur von 5 wurde bestimmt. Die Verbindung kristallisiert mit 4 Molekülen in der monoklinen Elementarzelle der Symmetrie P21/a.
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  • 47
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    Struktur und Reaktionen des Phosphinsäureesters Me2P(:O)OC(CF3)2C(CF3)2OH (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1566-1574 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structure and Reactions of the Phosphinic Ester Me2P(:O)OC(CF3)2C(CF3)2OHThe product obtained from the reaction of the Me3SiO-functional 1,3,2λ5-dioxaphospholane 1 with water or hydrogen chloride has the structure 2b of a phosphinate; the expected isomeric hydroxyphosphorane 2a has not been observed. The structure of 2b has been determined by X-ray crystal structure analysis. Crystals of 2b are monoclinic; space group P21/c. In the crystalline state 2b forms dimers, as a result of strong hydrogen bonding between the P(:O)-group of one molecule and the OH-group of a second molecule. Reactions of 2b with chlorotrimethylsilane in the presence of triethylamine resulted in cyclisation with formation of the phosphorane 1. With thionyl chloride 2b gave the cyclic chlorophosphorane 3, while 2b and 3 reacted with formation of the cyclic anhydride 4 of the hypothetical hydroxyphosphorane 2a.
    Notes: Das Produkt der Umsetzung des Me3SiO-funktionellen 1,3,2λ5-Dioxaphospholans 1 mit Wasser oder Chlorwasserstoff besitzt die Konstitution 2b eines Phosphinsäureesters; das erwartete isomere Hydroxyphosphoran 2a wird nicht beobachtet. Die Struktur von 2b wurde durch Röntgen-analyse bestimmt. 2b kristallisiert monoklin, Raumgruppe P21/c, und bildet im kristallinen Zu-stand Dimere, in denen starke Wasserstoffbrückenbindungen zwischen der P(:O)-Gruppe eines Moleküls und der OH-Gruppe eines zweiten Moleküls vorliegen. Durch Umsetzung von 2b mit Chlortrimethylsilan in Gegenwart von Triethylamin erfolgt Cyclisierung zum Phosphoran 1. Umsetzung von 2b mit Thionylchlorid liefert das cyclische Chlorphosphoran 3, während aus 2b mit 3 das Anhydrid 4 des hypothetischen Hydroxyphosphorans 2a gebildet wird.
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    Polycyclische Verbindungen, XVII. Versuche zur 1,4-Carbonylgruppen-Transposition bei Tetrahydrobenzocycloheptenon-Derivaten (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1584-1591 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycyclic Compounds, XVII. 1,4-Carbonyl Group Transposition Studies in the Tetrahydrobenzocycloheptenone SeriesThe protected carbonyl group in the seven-membered ring of the oxanorbornadiene 1 is shifted by the 1,4-carbonyl group transposition sequence 1 → 4 → 5 → 3 into the ortho-position of a methoxycarbonyl group. Thereby 1,2- and 3,4-disubstituted tetrahydrobenzocyclohepten-5-one derivatives 2 and 3 are available as well starting from 1. The compound 5 exists in solution predominantly as arene oxide 5B. Experiments to cleave the dioxolane ring led under additional formation of a five-membered ring to the lactol ethers 6.
    Notes: Die als Dioxolan geschützte Carbonylgruppe im Siebenring des Oxanorbornadiens 1 wird durch die 1,4-Carbonylgruppen-Transpositionsfolge 1 → 4 → 5 → 3 in die ortho-Position zu einer Methoxycarbonylgruppe verschoben. Dadurch werden ausgehend von 1 sowohl 1,2- als auch 3,4-disubstituierte Tetrahydrobenzocyclohepten-5-on-Derivate 2 und 3 zugänglich. Das Zwischen-produkt 5 liegt in Lösung überwiegend als Arenoxid 5B vor. Versuche zur Dioxolanspaltung führten unter zusätzlichem Fünfringschluß zu den Lactolethern 6.
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    Synthesen biologisch wichtiger Kohlenhydrate, 21. Asymmetrisch induzierte Synthese von Aminozuckern: Methyl-4-O-acetyl-3-acetylamino-2,3,6-tridesoxy-α-D-xylo-hexopyranosid (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1592-1602 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Biologically Important Carbohydrates, 21 Asymmetrically Induced Synthesis of Amino Sugars: Methyl 4-O-Acetyl-3-acetylamino-2,3,6-trideoxy-α-D-xylo-hexopyranosidetrans-4-Hexenal-((2R, 3R)tartaric acid dimethyl ester acetal) (6) is aminated in allylic position with metallic selenium and chloramine-T yielding the easily separable 3-tosylamino derivatives with D-(7) and L-glycero-configuration (8) at C-3. 7 is hydroxylated with osmium tetroxide giving the 4,5-dihydroxy-3-tosylamino-D-xylo-hexanal acetal 9 with high selectivity. By splitting off the carbonyl protecting group from 9 with HCl in methanol methyl 2,3,6-trideoxy-3-tosylamino-hexoside 11 is obtained. Detosylation of 11 with sodium in liquid ammonia and peracetylation gives methyl 4-O-acetyl-3-acetylamino-2,3,6-trideoxyhexoside 13 with D-configuration. The constitution of 11 and 13 is proved by mass spectrometry and the α-xylo-configuration is determined by means of the 1H-NMR spectra.
    Notes: trans-4-Hexenal-((2R, 3R)-weinsäure-dimethylester-acetal) (6) liefert nach allylischer Aminierung mit metallischem Selen und Chloramin-T die gut trennbaren 3-Tosylamino-Derivate mit D- (7) und L-glycero-Konfiguration (8) an C-3. 7 wird mit Osmiumtetroxid hoch selektiv zum 4,5-Dihydroxy-3-tosylamino-D-xylo-hexanal-acetal 9 hydroxyliert, aus dem durch Abspaltung der Carbonylschutzgruppe mit HCl in Methanol das Methyl-2,3,6-tridesoxy-3-tosylaminohexosid 11 entsteht. Dessen Detosylierung mit Natrium in flüssigem Ammoniak führt nach Peracetylierung zum D-konfigurierten Methyl-4-O-acetyl-3-acetylamino-2,3,6-tridesoxyhexosid 13, dessen Konstitution durch Massenspektrometrie und dessen α-xylo-Konfiguration durch 1H-NMR-Untersuchungen bewiesen wird.
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    Extreme sterische Hinderung: Synthese und Struktur des Tetra(tert-butyl)phosphonium-Kations  -  ein Fall von T-Symmetrie (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1612-1622 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Extreme Steric Hindrance: Synthesis and Structure of the Tetra(tert-butyl)phosphonium Cation  -  a Case of T-SymmetryStarting from [(CH3)3C]3P and following a series of quaternisation and ylidation steps under carefully controlled conditions, the [(CH3)3C]4P+ cation could be synthesized for the first time: [(CH3)3C]3P → [(CH3)3C]3PCH3⊕ → [(CH3)3C]3P=CH2 → [(CH3)3C]3PCH2CH3⊕ → [(CH3)3C]3-P=CHCH3 → [(CH3)3C]3PCH(CH3)2⊕ → [(CH3)3C]3P=C(CH3)2 → [(CH3)3C]4P⊕. All intermediates were isolated. The tetra(tert-butyl)phosphonium cation was further characterized in the form of the iodide and tetrafluoroborate by means of all spectroscopic methods available. An X-ray diffraction analysis of the BF4 salt showed a face-centered cubic lattice with a superstructure (space group F43c  -  Td5). The cation has T-symmetry as predicted by theoretical force field calculations with a tert-butyl twist of 14°. Due to the extreme steric hindrance, the P—C bond distances are elongated and the C—C—C angles compressed.
    Notes: Ausgehend von [(CH3)3C]3P konnte über eine Abfolge von Quartärisierungs- und Ylidierungsstufen erstmals das [(CH3)3C]4P⊕-Kation synthetisiert werden: [(CH3)3C]3P → [(CH3)3C]3PCH3⊕ → [(CH3)3C]3P=CH2 → [(CH3)3C]3PCH2CH3⊕ → [(CH3)3C]3P=CHCH3 → [(CH3)3C]3PCH-(CH3)2⊕ → [(CH3)3C]3P=C(CH3)2 → [(CH3)3C]4P⊕. Alle Zwischenprodukte wurden isoliert. Das Tetra(tert-butyl)phosphonium-Kation wurde als Iodid und Tetrafluoroborat spektroskopisch vollständig charakterisiert. Eine Röntgenbeugungsanalyse des BF4-Salzes zeigte, daß eine kubisch-flächen-zentrierte Packung mit Überstruktur vorliegt (Raumgruppe F43c  -  Td5). Das Kation besitzt die theoretisch vorhergesagte T-Symmetrie mit einem tert-Butyl-Twist von 14°. Wegen der extremen sterischen Hinderung sind überdies die P—C-Abstände verlängert und die C—C—C-Winkel verengt.
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    Untersuchungen an Diazoverbindungen und Aziden, XXXVII. Diazogruppen-Übertragung auf 2,3-Diphenylthiiren-1,1-dioxid mit Diazoalkanen (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 1632-1635 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations on Diazo Compounds and Azides, XXXVII. Diazo Group Transfer onto 2,3-Diphenylthiirene 1,1-Dioxide with DiazoalkanesThe thiirene 1,1-dioxide 6 reacts with diazoalkanes (2a - d) not only under diazo group transfer to give 9a or 10b and c but also under loss of sulfur dioxide to form pyrazoles (11b, c and 8d). The bicycles 7 are intermediates of both reactions.
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    Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, XXIV. P- und S-isomere Heteronickelacyclopentadiene als Abfangprodukte der instabilen dreigliedrigen Ringsysteme (h5-C5H5) mit aktivierten Alkinen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 46-54 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, XXIV. P- and S-isomeric Heteronickelacyclopentadienes as Trapping Products of the Unstable Three-membered Ring Systemswith Activated AlkynesThe unstable three-membered ring systems (2a, b) (L = h5-C5H5), which dimerize immediately at room temperature to give [LNiS=PR21]2 (3a, b), are obtained by reaction of L2Ni with diorganylphosphane sulfides R21HPS (1a, b). Between 2a, b and 3a, b there exists a dissociative equilibrium. 2a, b, however, are trapped with activated alkynes of the type R2C ≡ CR2 with formation of the S- and P-isomeric heteronickelacyclopentadienes (4aS - dS) and (4bP - dP) which can be differentiated by their colour and for R1=CH3 also with respect to the 1H NMR spectra. According to an X-ray structural analysis, 4aS crystallizes in the monoclinic space group P21/n with Z = 4.
    Notes: Bei der Umsetzung von L2Ni (L = h5-C5H5) mit den Diorganylphosphansulfiden R21HPS (1a, b) erhält man die instabilen, dreigliedrigen Ringsysteme (2a, b), die bei Raumtemperatur sofort zu [LNiS=PR21]2 (3a, b) dimerisieren. Zwischen 2a, b und 3a, b liegt ein dissoziatives Gleichgewicht vor. 2a, b lassen sich jedoch mit aktivierten Alkinen R2C ≡ CR2 unter Bildung der S- und P-isomeren Heteronickelacyclopentadiene (4aS - dS) und (4bP - dP) abfangen, welche sich in ihrer Farbe und für R1=CH3 auch in den 1H-NMR-Spektren unterscheiden. Nach einer Röntgenstrukturanalyse kristallisiert 4aS in der monoklinen Raumgruppe P21/n mit Z = 4.
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    Cycloadditionsreaktionen von Heterocumulenen, XXVI. Cycloaddukte aus Arylisothiocyanaten und 2,2-disubstituierten Enaminen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 55-65 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Heterocumulenes, XXVI. Cycloadducts from Aryl Isothiocyanates and 2,2-Disubstituted EnaminesAryl isothiocyanates 1 react with enamines 2 to give two types of 2:1 cycloadducts. Below 50°C, 1a - g and 2 give rise to 6-imino-1,3-thiazine-2-thiones 5, the constitutions of which are proved by an X-ray analysis of 5c. Above 50°C or starting from 4-nitrophenyl isothiocyanate (1h),2,4-dithiouracils 6 are formed. 1:1 cycloadducts of the reactants are detected spectroscopically; on workup, they hydrolyze to give 2-formylthiopropionanilides 9.
    Notes: Arylisothiocyanate 1 und Enamine 2 reagieren zu zwei Typen von 2:1-Cycloaddukten. Unterhalb von 50°C entstehen aus 1a - g und 2 6-Imino-1,3-thiazin-2-thione 5, deren Konstitution durch die Röntgenstrukturanalyse von 5c bewiesen wurde. Oberhalb 50°C oder aus 4-Nitrophenylisothio-cyanat (1h) bilden sich 2,4-Dithiouracile 6. 1:1-Cycloaddukte der Reaktanten lassen sich spektroskopisch nachweisen; bei der Aufarbeitung hydrolysieren sie zu 2-Formylthiopropionaniliden 9.
    Additional Material: 3 Tab.
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    Cycloadditionsreaktionen von Heterocumulenen, XXVII. 2-Alkyliden-1,3,4-thiadiazoline durch 1,3-dipolare Cycloaddition von Diazoalkanen an Thioketene (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 66-73 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Heterocumulenes, XXVI. 2-Alkylidene-1,3,4-thiadiazolines via 1,3-Dipolar Cycloaddition of Diazoalkanes to ThioketenesBased on 13C NMR data, the constitution of 2-alkylidene-1,3,4-thiadiazolines 3 is assigned to the 1 : 1 cycloadducts from thioketenes 1 and diazoalkanes 2a, b. The alkynyl silyl sulfide 15 also forms this heterocyclic system with 2a. However, the allyl(silyl)thioketene 12 reacts with 2a to give a 3 H-pyrazole 13b, which is derived from the addition to the C ≡ C bond of the valence tautomeric allyl silylethynyl sulfide 11.
    Notes: Aufgrund von 13C-NMR-Daten wird den 1 : 1-Cycloaddukten aus Thioketenen 1 und den Diazoalkanen 2a, b die 2-Alkyliden-1,3,4-thiadiazolin-Konstitution 3 zugeordnet. Auch das Alkinyl(silyl)sulfid 15 bildet mit 2a diesen Heterocyclen-Typ. Das Allyl(silyl)thioketen 12 reagiert mit 2a dagegen zu einem 3H-Pyrazol 13b, das sich von der Addition an die C ≡ C-Bindung des valenztautomeren Allyl(silylethinyl)sulfids 11 ableitet.
    Additional Material: 1 Tab.
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    Über Metallalkyl- und -aryl-Verbindungen, XXIX. Darstellung und Kristallstruktur von Methylnatrium mit variablen Methyllithium-Gehalten, Verbindungen mit (CH3Na)4- und (CH3Li)4-Einheiten (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 74-85 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Alkyl and Aryl Compounds, XXIX. Preparation and Crystal Structure of Methylsodium with Variable Methyllithium Content, Compounds with (CH3Na)4 and (CH3Li4) UnitsMethylsodium has been prepared by the reaction of methyllithium with sodium tert-butoxide. Depending upon the reaction conditions the preparations contain variable amounts of methyllithium (Na : Li atomic ratio ca. 36:1 to 3:1). Their crystal structures could be determined from powder diagrams. All preparations have a cubic unit cell (a = 2020 pm, space group F 43c) with 24 (CH3Na)4 units. Their geometry is analogous to that of (CH3Li)4 with distances Na—Na 312, 318, Na—C 258, 264, and Na—C 276 pm between adjacent tetramers. Due to their mutual arrangement 8 large cavities are formed which can incorporate (CH3Li)4 units up to a maximum ratio of (CH3Na)4: (CH3Li)4 = 3:1. - The bonding within the (CH3Na)4 groups resembles largely to that of (CH3Li)4 with more strongly polarized Na3C four-center bonds. The IR spectra of (CH3Na)4 and (CH3Li)4 are discussed.
    Notes: Methylnatrium wurde durch Umsetzung von Methyllithium mit Natrium-tert-butoxid erhalten. Je nach den Reaktionsbedingungen enthalten die Präparate variable Mengen an Methyllithium (Na:Li-Atomverhältnis ca. 36:1 bis 3:1). Ihre Kristallstrukturen konnten aus Pulverdiagrammen ermittelt werden. Alle Präparate haben eine kubische Elementarzelle (a = 2020 pm, Raumgruppe F 43 c) mit 24 (CH3Na)4-Einheiten. Ihre Geometrie ist analog der von (CH3Li)4 mit den Abständen Na—Na 312, 318, Na—C 258, 264 und Na—C 276 pm zwischen benachbarten Tetrameren. Infolge ihrer speziellen gegenseitigen Anordnung entstehen 8 große Hohlräume, welche (CH3Li)4 -Einheiten bis zu einem maximalen Verhältnis (CH3Na)4:(CH3Li)4 = 3:1 einschließen können. - Die Bindung in den (CH3Na)4-Gruppen entspricht noch weitgehend der von (CH3Li)4 mit stärker polarisierten Na3C-Vierzentrenbindungen. Die IR-Spektren von (CH3Na)4 und (CH3Li)4 werden diskutiert.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19831160109
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    Anwendung von Kraftfeldrechungen, IV. Ein Kraftfeld für die Berechnung von Struktur und Bildungsenthalpie von Alkylbenzolen und sein Verläßlichkeitstest an hochgespannten Diphenylethanen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 86-96 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Application of Force Field Calculations, IV. A Force Field for the Calculation of the Structures and Heats of Formation of Alkylbenzenes and its Test of Reliability on Highly Strained DiphenylethanesAllinger's force field MM26) was expanded to the calculation of the molecular structures and heats of formation of alkylated benzenes by additional parameters. Calculations on highly congested diphenylethanes were performed. These compounds are distinguished by long C—C-bonds, by large bond angle deformations and by high strain enthalpies (up to 45 kcal · mol-1). The excellent agreement between calculational results and experimentally determined data proves high reliability of the extended force field. - Furthermore strain-free increments for phenyl groups are given to put the strain enthalpies of phenyl and alkyl groups on the same scale.
    Notes: Zur Berechnung von Struktur und Bildungsenthalpie von Alkylbenzolen wurde das Kraftfeld MM2 von Allinger6) mit Parametern ergänzt. Testrechnungen wurden durchgeführt an hochverzweigten Diphenylethanen, die sich auszeichnen durch stark gedehnte C—C-Bindungen, aufgeweitete Bindungswinkel und hohe Spannungsenthalpien (bis zu 45 kcal · mol-1). Die ausgezeichnete Übereinstimmung der Rechenergebnisse mit experimentellen Daten belegt die hohe Verläßlichkeit des erweiterten Kraftfeldes. - Außerdem wurden spannungsfreie Inkremente für Phenylgruppen angegeben, um die Spannungsenthalpie einheitlich für Alkyl- und Phenylgruppen angeben zu können.
    Additional Material: 8 Tab.
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    Isomerenbildung bei der Umsetzung von Benzofurazen-N-oxiden mit Phenolat-Anionen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2380-2383 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Isomers in the Reaction of Benzofurazan N-Oxides with Phenolate AnionsBenzofurazan 1-oxide 1 reacts with 4-aminophenol in the presence of NaOCH3 to form the isomeric phenazine 5,10-dioxides 3, which are reduced to phenazines 4.
    Additional Material: 1 Tab.
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    Hetero-Cluster: Metallaustausch über zweikernige (Cyclopentadienyl)metallcarbonyle (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2409-2422 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mixed Metal Clusters: Metal Exchange via Dinuclear (Cyclopentadienyl)metal CarbonylsIn the tetrahedral cobalt cluster MeCCo3(CO)9 (2a) by means of the dinuclear (cyclopentadienyl)-metal carbonyls [CpM(CO)n+1]2 (1, M = Mo, W, Fe, Ni) one Co(CO)3 unit can be replaced by an isoelectronic unit CpM(CO)n. The best exchange reagent [CpNi(CO)]2 yields the corresponding mixed Co2Ni and Co3Ni clusters, resp. also with other YCCo3(CO)9 clusters (2, Y = Ph, p-Tol, F) and with Co4(CO)12. Thus, by combination of this method with the previously described organometal dimethylarsenide method from YCCo3(CO)9 (2, Y = Me, Ph) the clusters YCCoMoNiCp2(CO)5 (16) with three different metal atoms are obtained. Under modified reaction conditions twofold metal exchange in MeCCo3(CO)9 yields the cluster MeCCoMo2Cp2(CO)7 (15) and in PhCCo2MoCp(CO)8 yields the cluster PhCMoNi2Cp3(CO)2 (17). Of the CoMoNi compound 16a and the MoNi2 compound 17 the molecular structures were determined.
    Notes: In dem tetraedrischen Cobaltcluster MeCCo3(CO)9 (2a) läßt sich mit Hilfe der zweikernigen (Cyclopentadienyl)metallcarbonyle [CpM(CO)n+1]2 (1, M = Mo, W, Fe, Ni) eine Co(CO)3-Einheit durch eine isoelektronische Einheit CpM(CO)n ersetzen. Das beste Austausch-Reagens [CpNiCO]2 liefert auch mit anderen YCCo3(CO)9-Clustern (2, Y = Ph, p-Tol, F) und mit Co4(CO)12 die entsprechenden Co2Ni- bzw. Co3Ni-Heterocluster. Durch Kombination dieser Methode mit der vorstehend beschriebenen Organometall-dimethylarsenid-Methode lassen sich so aus YCCo3(CO)9 (2, Y = Me, Ph) die Cluster YCCoMoNiCp2(CO)5 (16) mit drei verschiedenen Metallatomen gewinnen. Unter veränderten Reaktionsbedingungen ergibt zweifacher Metallaustausch aus MeCCo3(CO)9 den Cluster MeCCoMo2Cp2(CO)7 (15) und aus PhCCo2MoCp(CO)8 den Cluster PhCMoNi2Cp3(CO)2 (17). Von der CoMoNi-Verbindung 16a und der MoNi2-Verbindung 17 wurden die Molekülstrukturen bestimmt.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19821150703
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    Zur Carbonylierung von Zirconocenhydrid-Komplexen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2447-2460 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Carbonylation of Zirconocene Hydride ComplexesThe reaction of η2-acylzirconocene complexes 1 with oligomeric zirconocene hydrides (Cp2ZrH2)x (3) or (Cp2ZrClH)x (4) yields binuclear μ-aldehyde-zirconocene hydride complexes 2. The molecular geometry of an example of this type of compound, the μ-acetaldehyde-zirconocene dihydride 2c, in the crystalline state was determined by X-ray analysis. A degenerate „dyotropic“ rearrangement of substrates 2c and e proceeding fast in solution can be detected by dynamic 1H NMR spectroscopy. Reaction of the dinuclear dihydride 2e with carbon monoxide eventually yields the enediolate complex 15-cis. The mechanism of this process of a reductive coupling of two CO molecules by substrate 2e can be traced by several established intermediates. The isolated (η2-formaldehyde)zirconocene complex 11 appears to have a key function in this transformation of carbon monoxide.
    Notes: Die Reaktion der η2-Acylzirconocen-Komplexe 1 mit den oligomeren Zirconocenhydriden (Cp2ZrH2)x (3) oder (Cp2ZrClH)x (4) führt zu zweikernigen μ-Aldehyd-zirconocenhydrid-Komplexen 2. Die molekulare Geometrie eines Beispiels dieser Verbindungsklasse, des μ-Acetaldehydzirconocendihydrids 2c, im Kristall wurde durch eine Röntgen-Strukturanalyse bestimmt. Eine in Lösung rasch verlaufende degenerierte „dyotrope“ Umlagerung der Substrate 2c und e kann durch dynamische 1H-NMR-Spektroskopie erkannt werden. Die Umsetzung des zweikernigen Dihydrids 2e mit Kohlenmonoxid führt schließlich zum Endiolatkomplex 15-cis. Der Mechanismus dieser reduktiven Kupplung zweier CO-Moleküle am Substrat 2e wird durch die nachgewiesenen Zwischenprodukte abgesteckt. Dem isolierten (η2-Formaldehyd)zirconocen-Komplex 11 kommt eine Schlüsselrolle bei dieser Umwandlung des Kohlenmonoxids zu.
    Additional Material: 3 Ill.
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    Zum Reaktionsverhalten von Trifluormethyl-Gruppen Synthese von 1,3-Azolen aus Trifluormethyl-substituierten Hetero-1,3-dienen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2494-2507 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction Behaviour of Trifluoromethyl Groups Synthesis of 1,3-Azoles from Trifluoromethyl-substituted Hetero-1,3-dienes4,4-Bis(trifluoromethyl)-substituted 1-oxa-3-aza-1,3-butadienes 1, 1-thia-3-aza-1,3-butadienes 2 as well as 1,3-diaza-1,3-butadienes 3 on heating with tin(II) chloride yield 5-fluoro-4-trifluoro-methyl-substituted oxazoles 4, thiazoles 5, and imidazoles 6, respectively. Reaction of the latter with nucleophiles leads to substitution of fluorine bonded to C-5. IR, 1H, 13C, and 19F NMR data of the new compounds are described. A reaction mechanism is proposed.
    Notes: 4,4-Bis(trifluormethyl)-bestückte 1-Oxa-3-aza-1,3-butadiene 1, 1-Thia-3-aza-1,3-butadiene 2 und 1,3-Diaza-1,3-butadiene 3 liefern beim Erhitzen mit wasserfreiem Zinn(II)-chlorid 5-Fluor-4-trifluormethyl-substituierte Oxazole 4, Thiazole 5 bzw. Imidazole 6. Letztere reagieren mit Nucleophilen unter Substitution des an C-5 gebundenen Fluors. Die IR-, 1H-, 13C- und 19F-NMR-Daten der neuen Verbindungen werden beschrieben. Ein Reaktionsmechanismus wird diskutiert.
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    Cycloadditionsreaktionen von Heterocumulenen, XXIV. Selenazol-Derivate aus Carbondiselenid und 3-(Dimethylamino)-2H-azirinen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2516-2525 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Heterocumulenes, XXIV. Selenazole Derivatives from Carbon Diselenide and 3-(Dimethylamino)-2H-azirines3-Selenazolines 5 result from the reaction of carbon diselenide (1) with 2-phenyl-substituted azirines 2a,b via 1,2-cleavage. In the 2,2-dimethylazirine 2c 1 induces 1,3-ring-opening to give the zwitterionic selenazoline 8a which in solution exists exclusively as isoselenocyanate 8B. Reactions of 8 are possible from form A as well as from B. The 2-monosubstituted azirine 2d reacts with 1 to give the 2,2′-biselenazole 23 and the 1-selenomesoxaldiamide 24. The constitution 23 was derived from an X-ray structural analysis.
    Notes: Aus Carbondiselenid (1) und den 2-Phenyl-substituierten Azirinen 2a, b entstehen unter 1,2-Bindungsspaltung die 3-Selenazoline 5. Beim 2,2-Dimethylazirin 2c bewirkt 1 1,3-Ringöffnung zum zwitterionischen Selenazolin 8a, das in Lösung ausschließlich als Isoselenocyanat 8B vorliegt. Reaktionen von 8 sind sowohl aus der Form A wie aus B möglich. Das 2-monosubstituierte Azirin 2d gibt mit 1 das 2.2′-Biselenazol 23 und das 1-Selenomesoxalsäure-diamid 24. Die Konstitution 23 ergibt sich aus einer Röntgenstrukturanalyse.
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    Radical ions, 51. Oxidative Rearrangement of Diphenyl Disulfides to Thianthrenes (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2548-2559 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radikalionen, 51. Oxidative Umlagerung von Diphenyldisulfiden in Thianthrenepara-Substituierte Diphenyldisulfide 1-5 mit niedrigen Ionisierungsenergien um 8 eV reagieren mit AlCl3 in CH2Cl2 zu Radikalionen der gleichartig substituierten Thianthrene (Tab. 2, Abb. 2). Beim Aufwärmen der Lösungen beobachtet man ein zweites ESR-Signal, das einem Benzodithiet-Radikalkation (Tab. 2, Abb. 3) zugeordnet wird. Dies ist möglicherweise das reaktive Zwischenprodukt der S8- oder S2Cl2-katalysierten Friedel-Crafts-Chlorierung von Benzol.
    Notes: para-Substituted diphenyl disulfides 1-5 with low gas phase ionization energies of about 8 eV react with AlCl3 in CH2Cl2 to form-radical cations of the corresponding thianthrenes (Table 2, Figure 2). Warming of these solutions produced a second ESR signal which is attributed to a benzodithiete radical cation (Table 2, Figure 3). This is possibly the reactive intermediate in the S8 or S2Cl2 catalyzed Friedel-Crafts chlorination of benzene.
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    The synthesis of spiro[adamantane-[1,2]dioxetanes] (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2592-2605 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Synthese von Spiro[adamantan-[1,2]dioxetanen]Die Spiroadamantangruppe stabilisiert thermisch unbeständige 1,2-Dioxetane ausreichend und ermöglicht dadurch deren Isolierung. Diese stabilisierende Gruppe erlaubt erstmals, schwefel-substituierte Dioxetane 9k und 1 herzustellen und mittels 13C- und 1H-NMR-Spektroskopie nachzuweisen. Tetraphenylporphyrin-photosensibilisierte Singulett-Sauerstoff-Cycloaddition an 2-Methylenadamantane 8 ist die Methode der Wahl zur Erzeugung der Spiro[adamantan-[1,2]-dioxetane] 9, vorausgesetzt, der Methylenkohlenstoff trägt keine Alkyl- oder Arylreste. Die Kopecky-Methode, d.h. Hydroperoxybromierung der 2-Methylenadamantane 8 und anschließende Dehydrobromierung, führt nicht zur Bildung der Dioxetane 9.
    Notes: It is shown that the spiroadamantane group stabilizes thermally labile 1,2-dioxetanes sufficiently to permit isolation. With the help of this stabilizing group it was possible to prepare the first sulfur substituted dioxetanes 9k and 1 and characterize them by low temperature 13C and 1 NMR spectra. Photosensitized singlet oxygenation at low temperature, using either polymer-bound Rose Bengal or tetraphenylporphyrin as sensitizer in methylene chloride, of the corresponding 2-methyleneadamantanes 8 was the method of choice for the preparation of the spiro[adamantane-[1,2]dioxetanes] 9, provided that the methylene carbon bears no alkyl or phenyl substituents. The Kopecky method, i.e. hydroperoxybromination of the 2-methyleneadamantanes 8 and subsequent dehydrobromination, proved unsuccessful to prepare the dioxetanes 9.
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    Eine neue Methode zur Darstellung von 2,4-disubstitutierten Morpholinen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2635-2642 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Method for the Synthesis of 2,4-Disubstituted Morpholinesω-Acetoxyacetophenones (acyloin esters) 1 react with secondary aminoethanols 3 and formic acid according to Leuckart-Wallach's reaction to form 2-(aryl),4-disubstituted morpholines 5. Intermediates of the reaction are discussed. The ω-halogenacetophenones react analogically.
    Notes: Bei der reduktiven Aminierung von ω-Acetoxyacetophenonen (Acyloinestern) 1 mit sekundären Aminoethanolen 3 und Ameisensäure nach der Leuckart-Wallach-Reaktion werden 2-(Aryl),4-disubstituierte Morpholine 5 gewonnen. Die Zwischenstufen der Reaktion werden diskutiert. Die ω-Halogenacetophenone reagieren analog.
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    Hetero-Cluster: Metallaustausch über Organometall-dimethylarsenide (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2385-2408 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mixed Metal Clusters: Metal Exchange via Organometal DimethylarsenidesReactions of the methylidyne-tricobalt clusters YCCo3(CO)9 (1, Y = H, Me, Ph, p-Tol, F) with the organometal dimethylarsenides Cp(CO)3M—AsMe2 (2-4, M = Cr, Mo, W) initially yield the addition products 5-7 through CO replacement. From these by heating a Co—As fragment is eliminated, whereby the new mixed metal cluster YCCo2MCp(CO)8 (9-11) are formed. Of the MeCCo2Mo compound 10c the molecular structure was determined. The mixed metal clusters allow for CO substitution by which also their prochirality can be proved. Attempts to perform corresponding metal exchange reactions with other tetrahedral cobalt clusters (PhPCo3(CO)9, Co4(CO)12, HFeCO3(CO)12, CpNiCo3(CO)9) or with other organometal dimethylarsenides M—AsMe2 (M = Cp(CO)2Fe, (CO)5Mn, Me3P(CO)4Mn) were only partially successful.
    Notes: Die Umsetzung der Methylidin-tricobalt-Cluster YCCo3(CO)9 (1, Y = H, Me, Ph, p-Tol, F) mit den Organometall-dimethylarseniden Cp(CO)3M—AsMe2 (2-4, M = Cr, Mo, W) liefert zunächst durch CO-Austausch die Additionsprodukte 5-7. Aus diesen wird beim Erhitzen ein Co—As-Bruchstück eliminiert, wobei sich die neuen Hetero-Clusters YCCo2MCp(CO)8 (9-11) bilden. Von dem MeCCo2Mo-Vertreter 10c wurde die Molekülstruktur bestimmt. In den Hetero-Clustern ist CO-Substitution möglich, wodurch sich auch ihre Prochiralität nachweisen läßt. Versuche, entsprechende Metallaustauschreaktionen auch an anderen tetraedrischen Cobaltclustern (PhPCo3(CO)9, Co4(CO)12, HFeCo3(CO)12, CpNiCo3(CO)9) oder mit anderen Organometall-dimethylarseniden M—AsMe2 (M = Cp(CO)2Fe, (CO)5Mn, Me3P(CO)4Mn) durchzuführen, waren nur zum Teil erfolgreich.
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    Isocyanidkomplexe, III. Organosulfonylisocyanid-Cr(CO)5-Komplexe (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2423-2427 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isocyanide Complexes, III. Organosulfonyl Isocyanide Cr(CO)5 ComplexesThe reaction of K[(CO)5CrCN] with RSO2Cl (R = Me, Et, CH2Ph, Ph, p-MeC6H4 and p-FC6H4) yields the complexes (CO)5CrCNSO2R (3a-f). The compounds are characterized by their IR, NMR, and mass spectra.
    Notes: Bei der Umsetzung von K[(CO)5CrCN] mit RSO2Cl (R = Me, Et, CH2Ph, Ph, p-MeC6H4 und p-FC6H4) entstehen die Komplexe (CO)5CrCNSO2R (3a-f), die anhand ihrer IR-, NMR- und Massenspektren charakterisiert werden.
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    Dyotrope Umlagerungen zweikerniger μ-Aldehyd-zirconocen-Komplexe (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2437-2446 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dyotropic Rearrangements of Dinuclear μ-Aldehyde-zirconocene ComplexesIn solution dinuclear μ-aldehyde-zirconocene complexes 3a-h exhibit a dynamic behavior which shows features as being expected for a dyotropic rearrangement process. In view of the presumed structure of complexes 3 the remarkably low activation barriers of these thermally induced degenerate rearrangements, as determined by dynamic NMR spectroscopy (e.g. 3a: δG-129°C≠ = 7 kcal mol-1), could be interpreted to result primarily from a substantial ground state effect.
    Notes: Die zweikernigen μ-Aldehyd-zirconocen-Komplexe 3a-h zeigen in Lösung ein dynamisches Verhalten, das die erwarteten Eigenschaften einer dyotropen Umlagerung aufweist. Auf Grund der anzunehmenden Struktur der Komplexe 3 können die durch dynamische NMR-Spektroskopie bestimmten erstaunlich niedrigen Aktivierungsbarrieren dieser degenerierten thermischen Umlagerungen (z.B. 3a: δG-129°C≠ = 7 kcal mol-1) in erster Linie als Ausdruck eines ausgeprägten Grundzustandseffektes interpretiert werden.
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    Fragmentierende Ringverengungen des 1:2-Addukts aus Pyridin und Acetylendicarbonsäure-dimethylester (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2467-2477 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fragmentative Ring Contractions of the 1:2-Adduct of Pyridine and Dimethyl Acetylene-dicarboxylateThe structure 1a is secured for the 1:2-adduct of pyridine and dimethyl acetylenedicarboxylate. Its UV/VIS and 1H NMR spectra are temperature-dependent. Dichromate oxidation of 1a produces not only the indolizine 3, but also the quinolizinone 4. The indolizines 8, 3, 9, and 10 are formed in the ratio 10:5:5:1 upon thermolysis of 1a at 220°C, whereas 4 is stable under these conditions. The complex ring contractions with fragmentations and in part rearrangements are classified and interpreted mechanistically (high energy valence tautomers; cyclopropane-, ylide-, zwitterion/diradical-intermediates). The gaseous and liquid further products of the thermolysis are compatible with the intermediacy of carbene and radical fragments. Analytical and spectroscopic data (UV, fluorescence, IR, 1H, 13C NMR, MS) as well as independent syntheses (3, 10) and the synthesis of the reference compound 12 secure the constitutions of the compounds.
    Notes: Für das 1:2-Addukt aus Pyridin und Acetylendicarbonsäure-dimethylester wird die Konstitution 1a gesichert. Die UV/VIS- und 1H-NMR-Spektren sind temperaturabhängig. Die Dichromat-Oxidation von 1a liefert nicht nur das Indolizin 3, sondern auch das Chinolizinon 4. Die Thermolyse von 1a bei 220°C ergibt die Indolizine 8, 3, 9 und 10 im Verhältnis 10:5:5:1, während 4 unter diesen Bedingungen stabil ist. Die komplizierten Ringverengungen mit Fragmentierungen und teilweise Umlagerungen werden klassifiziert und mechanistisch gedeutet (energiereiche Valenztautomere; Dreiring-, Ylid-, Zwitterion/Diradikal-Intermediate). Die gasförmigen und flüssigen weiteren Produkte der Thermolyse stehen im Einklang mit dem Auftreten von Carben- und Radikal-Fragmenten, die aus den formulierten Intermediaten entstehen sollten. Zur Konstitutionssicherung dienen analytische und spektroskopische (UV, Fluoreszenz, IR, 1H-, 13C-NMR, MS) Daten sowie unabhängige Synthesen (3, 10) und die Synthese der Referenzverbindung 12.
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    Dreikernige Ruthenium-Clusteranionen mit Triorganylsilyl-, -germyl- und -stannylliganden (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2487-2493 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Trinuclear Ruthenium Cluster Anions Containing Triorganylsilyl, -germyl, and -stannyl LigandsThe reaction of Na[HRu3(CO)11] with triorganylsilanes, -germanes, and -stannanes R'R2XH (X = Si, Ge, Sn; R, R' = organyl) affords trinuclear cluster anions of the type [HRu3(CO)10(XR2R')2]-, which can be isolated as the bis(triphenylphosphoranyliden)ammonium or the tetraethylammonium salts. The structure of an isosceles Ru3 triangle with one hydride bridge and two XR2R' ligands at the bridgehead ruthenium atoms is proposed for the anions on the basis of NMR evidence. The reaction proceeds under elimination of H2 and CO and is reversible; the formation of [HRu3(CO)10(SiEt3)2]- from [DRu3(CO)11]- and Et3SiH reveals the eliminated hydrogen to be arising from the cluster.
    Notes: Die Umsetzung von Na[HRu3(CO)11] mit Triorganylsilanen, -germanen und -stannanen R'R2XH (X = Si, Ge, Sn; R, R' = organyl) führt zu dreikernigen Clusteranionen des Typs [HRu3(CO)10(XR2R')2]-, die sich als Bis(triphenylphosphoranyliden)ammonium- bzw. Tetraethylammonium-Salze isolieren lassen. Aufgrund der spektroskopischen Befunde wird für die Anionen die Struktur eines gleichschenkligen Ru3-Dreiecks mit einer Hydridbrücke und zwei XR2R'-Liganden an den beiden Brückenkopf-Rutheniumatomen vorgeschlagen. Die Reaktion verläuft unter Eliminierung von H2 und CO und ist reversibel; die Bildung von [HRu3(CO)10(SiEt3)2]- aus [DRu3(CO)11]- und Et3SiH zeigt, daß der freigesetzte Wasserstoff aus dem Cluster eliminiert wird.
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    Übergangsmetall-Schwefelylid-Komplexe, XIV. π-Komplexe von 1-Alkyl-3,5-diphenyl-λ4-thiabenzolen mit Dicarbonylnitrosylchrom (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 197-206 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Sulfur Ylide Complexes, XIV. π-Complexes of 1-Alkyl-3,5-diphenyl-λ4-thiabenzenes with Dicarbonylnitrosylchromium1-Alkyl-3,5-diphenyl-λ4-thiabenzene chromium complexes 2a-f are oxidized by NOPF6 in CH2Cl2 at -70°C, yielding the cationic dicarbonylnitrosyl complexes 3a-f. The temperature dependence of the 1H NMR spectra of 3a-f is consistent with a hindered rotation of the ring ligands. The X-ray structure analysis of 3b shows that the molecule in the solid state possesses no local Cs-symmetry.
    Notes: Die 1-Alkyl-3,5-diphenyl-λ4-thiabenzol-Chromkomplexe 2a-f werden durch NOPF6 in CH2Cl2 bei -70°C unter Bildung der kationischen Dicarbonylnitrosyl-Spezies 3a-f oxidiert. Die temperaturabhängigen 1H-NMR-Spektren dieser Komplexe deuten auf gehinderte Rotation der Ringe um das (CO)2(NO)Cr+-Fragment hin. Die Röntgenstrukturanalyse von 3b zeigt, daß das Molekül im Kristall keine lokale Cs-Symmetrie mehr besitzt.
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    URL: http://dx.doi.org/10.1002/cber.19831160122
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    Stereologe Kronenether: π-Donorbeteiligung bei der Komplexierung von Kationen? (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 215-219 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereologous Crown Ethers: π-Donor Participation in the Complexation of Cations?In the framework of the “stereology concept” the new crown ethers 8, 9, and for comparison 11 have been synthesized and their stability constants with Ag+ ions determined by 1H NMR spectroscopy. The results may be interpreted as evidence for a π-participation of aromatic nuclei of the ligands in the complexation of certain cations.
    Notes: Im Rahmen des „Stereologie-Konzepts“ wurden die neuartigen Kronenether 8, 9 und zum Vergleich 11 synthetisiert und deren Komplexkonstanten gegenüber Ag+-Ionen 1H-NMR-spektroskopisch ermittelt. Die Befunde machen eine π-Donorbeteiligung aromatischer Kerne bei der Komplexierung bestimmter Kationen wahrscheinlich.
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    URL: http://dx.doi.org/10.1002/cber.19831160124
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    Neue helicale Kohlenwasserstoffe, VIII. Enantiomerentrennung, Circulardichroismus, Racemisierung und Röntgenstrukturanalyse des Benzo[2.2]metacyclophans (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 207-214 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Helical Hydrocarbons, VIII. Enantiomer Separation, Circular Dichroism, Racemization, and X-Ray Analysis of Benzo[2.2]-metacyclophaneThe title compound 1 was separated into the enantiomers by chromatography on cellulose triacetate: (-)-1 exhibits an enantiomeric purity of 100% with [α]36520 = -3210 ± 135 (acetone). A racemization barrier ΔG≠ = 125 kJ/mol is found by means of a kinetic study. The helicity of the molecule is demonstrated through these results as well as through an X-ray analysis, which is also described.
    Notes: Die Titelverbindung 1 wird chromatographisch an Cellulosetriacetat in die Enantiomeren getrennt: (-)-1 hat mit 100% Enantiomerenreinheit einen Drehwert von [α]36520 = -3210 ± 135 (Aceton). Für die Racemisierung wird kinetisch eine Barriere ΔG≠ = 125 kJ/mol ermittelt. Der helicale Molekülbau ist hiermit und durch die Röntgenstrukturanalyse gesichert, die gleichfalls beschrieben wird.
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    URL: http://dx.doi.org/10.1002/cber.19831160123
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    Isomerisierung von 2-Alkoxycyclopropancarbonsäuren - Eine effektive Synthese von 4-Oxocarbonsäuren (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 220-229 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isomerisation of 2-Alkoxycyclopropanecarboxylic Acids - An Effective Synthesis of 4-Oxo Carboxylic Acids(Z/E)-2-2-Alkoxycyclopropanecarboxylic esters 2/3 were prepared from enol ethers 1 and ethyl diazoacetate. The saponification of these esters gives the corresponding (Z/E)-2-alkoxycyclopropanecarboxylic acids 4/5, which show stereomutation in water/methanol. This isomerisation was studied in labelled solvents and interpreted for the example of (E)-2-methoxy-2-phenylcyclopropanecarboxylic acid (5a). On heating in water/methanol the compounds 4/5 are transformed quantitatively into the corresponding 4-oxo carboxylic acids 6.
    Notes: (Z/E)-2-Alkoxycyclopropansäureester 2/3 werden aus Enolethern 1 und Diazoessigester hergestellt. Durch Verseifen entstehen die (Z/E)-2-Alkoxycyclopropancarbonsäuren 4/5, welche in Wasser/Methanol Stereomutation zeigen. Diese Isomerisierung wird an (E)-2-Methoxy-2-phenyl-cyclopropancarbonsäure (5a) in deuterierten Lösungsmitteln untersucht und mechanistisch interpretiert. Beim Erwärmen in Wasser/Methanol öffnen sich die Verbindungen 4/5 quantitativ zu den entsprechenden 4-Oxocarbonsäuren 6.
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    (Cycloalkeno-1,2,3-selenadiazol- und -thiadiazol)carbonyl-(6B)-metall-Komplexe (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 230-237 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloalkeno-1,2,3-selenadiazole and -thiadiazole Carbonyl Complexes of Chromium, Molybdenum, and TungstenThe reactions of cycloalkeno-1,2,3-selenadiazoles 1 and -thiadiazoles 2 with pentacarbonyl-(6B)-metal(THF) complexes afford stable compounds M(CO)5(selenadiazole) (3-5) and M(CO)5(thiadiazole) (6) with the heteroaromatic ligand coordinating via its nitrogen atom in the 2-position. Reactions of cyclohexa-1,2,3-selenadiazole 1b with Mo(CO)4(norbornadiene) and with Mo(CO)3(CH3CN)3 produce a Mo(CO)4(selenadiazole)2 complex with the two terminal selenadiazole ligands in the cis-position, and a complex [Mo(CO)3]2(selenadiazole)3 with three bridging ligands, respectively. The reaction of Fe2(CO)9 with W(CO)5(selenadiazole), as compared with the free ligand, leads to a small variation of the formed products which might be explained with the intermediate formation of a labile dinitrogen pentacarbonyltungsten complex.
    Notes: Cycloalkeno-1,2,3-selenadiazole 1 und -thiadiazole 2 reagieren mit Pentacarbonyl-(6B)-metall-(THF) zu stabilen Komplexen der Zusammensetzung M(CO)5 (Selenadiazol) (3-5) und M(CO)5(Thiadiazol) (6), wobei die heteroaromatischen Liganden jeweils über N(2) komplexiert sind. Die Reaktionen von Cyclohexa-1,2,3-selenadiazol 1b mit Mo(CO)4(Norbornadien) und mit Mo(CO)3(CH3CN)3 führen zu cis-Mo(CO)4(Selenadiazol)2 mit zwei terminalen und zu [Mo(CO)3]2(Selenadiazol)3 mit drei verbrückenden Selenadiazol-Liganden. Bei der Umsetzung von W(CO)5(Selenadiazol) mit Nonacarbonyldieisen wird ein, verglichen mit der analogen Reaktion des freien Liganden, veränderter Reaktionsverlauf beobachtet, was mit der Bildung einer labilen Stickstoff-pentacarbonylwolfram-Zwischenstufe erklärt werden könnte.
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    Untersuchungen an Diazoverbindungen und Aziden, XLII. (Diazomethyl)cyclopropene durch elektrophile Diazoalkan-substitution (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2965-2980 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on Diazo Compounds and Azides, XLII. (Diazomethyl)cyclopropenes by Electrophilic Diazoalkane SubstitutionThe (diazomethyl)cyclopropenes 9 and 10 are formed via electrophilic diazoalkane substitution preferably of diazomethylphosphoryl compounds with cyclopropenylium salts. Either the diazomethyl compounds (7a-c) react with the cyclopropenylium salts 6a-e in the presence of triethylamine (method A) or the metallated diazo compounds 8a-d are combined with the cyclopropenylium bromides 6c-e (method B) (details see table 1). The (diazomethyl)cyclopropenes undergo a novel type of isomerization to pyridazines, partly without heating (9d-f → 11b-d), partly by refluxing in toluene (9a,g → 11a,e as well as 10e,f → 12a,b). The bicyclic betaines 15 and 17 are supposed to be intermediates. The diazomethyl compounds 9a and b yield the α,β- unsaturated ketones 20a and b by acid-catalyzed decomposition.
    Notes: Die (Diazomethyl)cyclopropene 9 und 10 entstehen durch elektrophile Substitution vorzugsweise von Diazomethylphosphorylverbindungen mit Cyclopropenyliumsalzen. Man setzt entweder die Diazomethylverbindungen selbst (7a-c) in Gegenwart von Triethylamin mit den Cyclopropenyliumsalzen 6a-e um (Methode A) oder läßt die metallierten Diazoverbindungen 8a-d mit den Cyclopropenyliumbromiden 6c-e reagieren (Methode B) (Details s. Tab. 1). Die (Diazomethyl)-cyclopropene gehen teils ohne Erwärmen (9d-f → 11b-d), teils beim Erhitzen in Toluol (9a,g → 11a,e sowie 10e,f → 12a,b) eine neuartige Isomerisierung zu Pyridazinen ein; Zwischenstufen sind vermutlich die bicyclischen Betaine 15 und 17. Die Diazomethylverbindungen 9a und b liefern bei der säurekatalysierten Zersetzung die α,β-ungesättigten Ketone 20a und b.
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    Addukte von Lewis-Säuren mit 1,2,4λ4,3,5-Trithiadiazol-1-oxid (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3025-3031 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Adducts of Lewis Acids with 1,2,4λ4,3,5-Trithiadiazole 1-OxideThe tittle compound 1 reacts with the Lewis acids SnCl4 and TiCl4 to yield the 2:1 adducts 1a and b and with AsF5 and SbF5 to form the 1:1 adducts 1c and d. According to the vibrational spectra and an X-ray analysis of 1a the coordination occurs via the oxygen atom. The ligands of 1a and b have cis-configuration. 1a crystallizes in the monoclinic space group P21.
    Notes: Die Titelverbindung 1 reagiert mit den Lewis-Säuren SnCL4 und TiCl4 zu den 2:1-Addukten 1a und b und mit AsF5 und SbF5 zu den 1:1-Addukten 1c und d. Nach den Schwingungsspektren und einer Röntgenstrukturanalyse von 1a erfolgt die Koordination über das Sauerstoffatom, und die Liganden in 1a und b haben cis-Konfiguration. 1a kristallisiert in der monoklinen Raumgruppe P21.
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    Präparative Enantiomerentrennung von axial- und planarchiralen Benzolderivaten, Metallocenen und Methanoaza[10]annulenen durch Mitteldruckchromatographie an Triacetylcellulose (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3042-3048 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparative Optical Resolution of Axial- and Planar-chiral Benzene Derivatives, Metallocenes, and Methanoaza[10]annulenes by Medium Pressure Chromatography on TriacetylcelluloseMedium pressure chromatography (at 4-6 bar and 6-40°C) on specially prepared triacetylcellulose in ethanol (or ether) renders possible an efficient preparative optical resolution of chiral benzene derivatives, (benzene)tricarbonylchromium complexes (benchrotrenes), ferrocenes, and azaannulenes. The method is presented for 15 selected examples such as 1,3-diferrocenyl-1,3-diphenylallene (1), 2,2′-spirobiindanes (2, 3), biphenyl derivatives (4-8) and their tricarbonylchromium complexes (9-11), [2.2]metacyclophanes (12-14) and 2,7-methanoaza[10]annulenes (15, 16) as well as for Troeger's base. In ten cases a quantitative separation of the enantiomers and in two an appr. 80 percent enantiomeric enrichment was achieved whereas for three compounds only a partial resolution took place.
    Notes: Mitteldruckchromatographie (bei 4-6 bar und 6-40°C) an speziell präparierter Triacetylcellulose in Ethanol (oder Ether) ermöglicht eine effiziente präparative Enantiomerentrennung chiraler Benzolderivate, (Benzol)tricarbonylchrom-Komplexe (Benchrotrene), Ferrocenderivate und Azaannulene. Die Methode wird an 15 ausgewählten Beispielen wie 1,3-Diferrocenyl-1,3-diphenylallen (1), 2,2′-Spirobiindanen (2, 3), Biphenylderivaten (4-8) und ihren Tricarbonylchrom-Komplexen (9-11), [2.2]Metacyclophanen (12-14) und 2,7-Methanoaza[10]annulenen (15, 16) sowie an der Trögerschen Base präsentiert. In zehn Fällen gelang eine quantitative Enantiomerentrennung, in zwei erfolgte eine etwa 80prozentige enantiomere Anreicherung und bei drei Verbindungen konnte partielle Trennung erzielt werden.
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    Cycloadditionsreaktionen von Organometallkomplexen, I. Die Synthese viergliedriger Metalla-Heterocyclen durch [2 + 2]-Cycloaddition aus (Isonitril)cobalt-Komplexen und Isocyanaten sowie Isothiocyanaten (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3069-3084 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Organometal Complexes, I. The Synthesis of Four-membered Metalla-Heterocycles by [2 + 2] Cycloaddition of (Isonitrile)-cobalt Complexes and Isocyanates or IsothiocyanatesThe reaction of C5H5(PMe3)CoCNR (R = Me, Ph) with isocyanates OCNR' (R' = Me, Ph) leads to the metalla-heterocycles in nearly quantitative yields. The analogous four-membered ring compounds (4-6) are obtained from C5H5(PMe3)CoCNR (R = Me, Ph, c-C6H11) and SCNMe. In the reactions of C5H5(PMe3)CoCNtBu with SCNMe and of C5H5(PMe3)CoCNMe with SCNtBu the complex (4) is also formed. The X-ray structure analyses of 4 and 5 show the presence of planar four-membered CoCNC rings together with a trigonal-planar coordination of the corresponding C, N and C ring atoms. The protonation and methylation reactions of the metalla-heterocycles 1-5 yield diaminocarbene complexes, in most cases by preserving the four-membered CoCNC-ring. The structure of these complexes is discussed on the basis of their IR and NMR data.
    Notes: Die Reaktion von C5H5(PMe3)CoCNR (R = Me, Ph) mit Isocyanaten OCNR' (R' = Me, Ph) führt nahezu quantitativ zu den Metalla-Heterocyclen (1-3). Die analogen Vierring-Verbindungen (4-6) sind ausgehend von C5H5(PMe3)CoCNR (R = Me, Ph, c-C6H11) und SCNMe zugänglich. Bei den Umsetzungen von C5H5(PMe3)CoCNtBu mit SCNMe und von C5H5(PMe3)CoCNMe mit SCNtBu bildet sich ebenfalls der Komplex (4). Die Röntgenstrukturanalysen von 4 und 5 beweisen das Vorliegen planarer CoCNC-Vierringe mit ebenfalls trigonal-planar koordinierten C-, N- und C-Atomen. Die Protonierungs- und Methylierungsreaktionen der Metalla-Heterocyclen 1-5 ergeben -- in den meisten Fällen unter Erhalt der CoCNC-Vierringstruktur - Diaminocarben-Komplexe. Ihre Struktur wird anhand der IR- und NMR-Daten diskutiert.
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    Stereospezifische Cyclisierung von 2-(3-Hexenyl)-1,3-dimethyl-2-cyclohexen-1-ol mit Z- und E-Konfiguration (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3128-3140 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereospecific Cyclization of 2-(3-Hexenyl)-1,3-dimethyl-2-cyclohexen-1-ol with Z- and E-ConfigurationCyclization of 4a (Z) with formic acid leads selectively to the products with trans-configurated side chain: 5a (byproduct), 6a, and 7a. Starting from 4b (E), the products with cis-configurated side chain are exclusively formed: 5b (byproduct), 6b, and 7b. The constitution of the cyclization products was demonstrated by degradation to the diketones 10, 11. The elucidation of the relative configuration at C-7 was achieved by oxidation of 5a and 6a to 12a (trans), 5b and 6b to 12b (cis), 7a to 13a (trans), and 7b to 13b (cis). By alkaline equilibration of 12a/12b and 13a/13b the correlation between the stereochemical series was delineated. Reduction of the ketones gave 5a (from 12a), 5b (from 12b), 14a (from 13a), and 14b (from 13b). By this, all the diastereomeric racemates, which are possible in these series, were prepared and the relative configurations, given above, could be demonstrated.
    Notes: Die Cyclisierung von 4a (Z) mit Ameisensäure verläuft stereospezifisch zu den Produkten mit trans-konfigurierter Seitenkette: 5a (Nebenprodukt), 6a und 7a. Aus 4b (E) entstehen ausschließlich die Produkte mit cis-konfigurierter Seitenkette: 5b (Nebenprodukt), 6b und 7b. Die Konstitutionen der Cyclisierungsprodukte wurden durch Abbau zu den Diketonen 10, 11 bewiesen. Für die Aufklärung der relativen Konfiguration an C-7 wurden 5a und 6a zu 12a (trans), 5b und 6b zu 12b (cis), 7a zu 13a (trans) und 7b zu 13b (cis) oxidiert. Durch alkalische Äquilibrierung von 12a/12b und 13a/13b wurde die Verknüpfung der stereochemischen Reihen aufgezeigt. Reduktion der Ketone ergab 5a (aus 12a), 5b (aus 12b), 14a (aus 13a) und 14b (aus 13b). Damit lagen alle hier möglichen diastereomeren Racemate vor, so daß die angegebenen relativen Konfigurationen zugeordnet werden konnten.
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    Correction (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3685-3685 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19821151121
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    Masthead (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982) 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19821151201
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  • 82
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    Darstellung von Enolsulfonsäureestern aus Trimethylsilylenolethern  -  Synthetische Konsequenz eines bemerkenswerten Kationeneffekts (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3687-3696 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation of Vinylsulfonates from Trimethylsilyl Enol Ethers  -  Synthetic Consequences of a Remarkable Cation EffectThe C/O-selectivity observed in the sulfonylation of the enolate ion 5 with benzenesulfonyl fluoride depends strongly on the nature of the gegenion. Li⊕ yields the β-oxosulfone 3 by C-sulfonylation exclusively. The fraction of O-Sulfonylation is increased with the size of the cation, yielding the vinylsulfonates 6b exclusively in the presence of Cs⊕ or quaternary ammonium ions. From this behaviour a regio- and stereoselective synthesis of vinylsulfonates is developed starting from the corresponding trimethylsilyl enol ethers.
    Notes: Die C/O-Selektivität der Sulfonylierung des Enolat-Ions 5 mit Benzolsulfonylfluorid zeigt einen starken Einfluß des Gegenions. Während mit Li⊕ ausschließlich C-Sulfonylierung zum β-Oxosulfon 3 erfolgt, wächst mit der Größe des Kations der Anteil an O-Sulfonylierung, bis mit Cs⊕ oder quartären Ammonium-Ionen ausschließlich Enolsulfonsäureester 6b entstehen. Dieses Verhalten wird für eine regio- und stereoselektive Synthese von Enolsulfonsäureestern aus den entsprechenden Trimethylsilyl-enolethern genutzt.
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    Synthese und Umlagerung substituierter Bicyclo[2.1.0]pent-2-ene. Eine thermische „walk“-Umlagerung (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 299-322 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Rearrangement of Substituted Bicyclo[2.1.0]pent-2-enes. A Thermal “Walk”-RearrangementThe synthesis and the thermal behaviour of methyl 5-methyl-, 1,5-, and 2,5-dimethylbicyclo-[2.1.0]pent-2-ene-5-carboxylates 3a, b, 4a, b, 5a, b, as well as of 1,5- and 2,5-dimethylbicyclo-[2.1.0]pent-2-ene-5-carbonitriles 6a, 7a, b are reported. The “walk”-rearrangement which is degenerate in the cases of 3a, b could be detected experimentally with the aid of the dimethyl derivatives 4a, b, 5a, b, 6a, and 7a, b. Electrocyclic ring opening to the correspondingly substituted 1,3-cyclopentadienes competes with the “walk”-rearrangements. Already at 0°C the “walk”-rearrangements 4a → 5a, 4b → 5b, and 6a → 7a proceed stereospecifically with inversion at the migrating carbon atom C-5 as postulated by Woodward and Hoffmann (0°C: ΔG* = 21.7, 24.8, and 21.9 kcal/mol). We assume that the surprisingly low activation barriers do not only result from the resonance stabilization of an aromatic transition state but largely from the anomalously high ground-state enthalpy of the bicyclopentene system.
    Notes: Synthese und thermisches Verhalten der 5-Methyl-, 1,5-Dimethyl- und 2,5-Dimethylbicyclo-[2.1.0]pent-2-en-5-carbonsäure-methylester 3a, b, 4a, b, 5a, b und -carbonitrile 6a, 7a, b werden beschrieben. Die in den Systemen 3a, b strukturell entartete „walk“-Umlagerung konnte am Beispiel der Dimethylderivate 4a, b, 5a, b, 6a und 7a, b experimentell nachgewiesen werden. Dazu konkurrierend finden elektrocyclische Ringöffnungen zu den entsprechend substituierten 1,3-Cyclopentadienen statt. Die „walk“-Umlagerungen 4a → 5a, 4b → 5b und 6a → 7a erfolgen bereits bei 0°C stereospezifisch mit der von Woodward und Hoffmann postulierten Inversion am wandernden Kohlenstoff C-5 (0°C: ΔG* = 21.7, 24.8 bzw. 21.9 kcal/mol). Vermutlich resultieren die überraschend niedrigen Aktivierungsbarrieren nicht allein aus der Resonanzstabilisierung eines aromatischen Übergangszustandes, sondern wesentlich aus der anomal hohen Grundzustandsenthalpie des Bicyclopentensystems.
    Additional Material: 7 Tab.
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    Pseudo-einstufige C—C-Spaltungen beim Zerfall von ionisierten Carbonsäuren. Radikaltypische Reaktionen in der Massenspektrometrie (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 323-347 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pseudo One-Step Cleavage of C—C Bonds in the Decomposition of Ionized Carboxylic Acids. Radical Like Reactions in Mass SpectrometryMetastable molecular ions of hexanoic acid (1) decompose unimolecularly to C2H5· and protonated methacrylic acid (5-Hℸ +) (92% rel. abund.). Investigation of the mechanism reveals that 1) the branched cation radical 11 must be regarded as the essential intermediate in the course of the rearrangement/dissociation reaction and 2) the process commences with intramolecular hydrogen transfer from either C-3 or C-5 to the ionized carbonyl oxygen („hidden“ hydrogen migration). Hydrogen transfer from C-4, which would correspond to the well-known McLafferty rearrangement, is of no importance in the C2H•5-elimination from 1. The same conclusion applies for various alternative mechanisms, as for example a SRi type reaction, 1 → 2-Hℸ +. The gas phase chemistry of the cation radical of 1, and in particular the hydrogen exchange processes between the methylene groups C-2/C-3 and C-5/C-6, is in surprisingly close correspondence to the chemistry of free alkyl radicals. - The syntheses of various 13C and 2H-labelled model compounds are described.
    Notes: Metastabile Molekül-Ionen von Hexansäure (1) zerfallen unimolekular zu C2H5· und protonierter Methacrylsäure (5-Hℸ +) (92% rel. Intensität). Untersuchungen zum Mechanismus der Reaktion enthüllen, daß 1. das verzweigte Radikalkation 11 als entscheidende Zwischenstufe im Umlagerungs-/Eliminierungsprozeß fungiert und 2. die Reaktion durch einen intramolekularen Wasserstofftransfer von sowohl C-3 als auch C-5 auf die ionisierte Carboxylgruppe eingeleitet wird („verborgene“ H-Wanderung). Wasserstoffübertragungen von C-4, analog zum bekannten McLafferty-Typus, spielen beim Zerfall von 1 keine Rolle. Dies gilt auch für diverse mechanistische Varianten, wie z. B. eine SRi-Reaktion 1 → 2-Hℸ +, die ebenfalls ohne Bedeutung sind. Die Gasphasenchemie des Radikalkations von 1 - und hier vor allem die Wasserstoff-Austauschprozesse zwischen den Methylengruppen C-2/C-3 und C-5/C-6 - zeigt eine überraschende Verwandtschaft zur Chemie freier Alkylradikale. - Die Synthesen 13C- und 2H-markierter Modellverbindungen werden beschrieben.
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    Nachweis von 4-Homocubyl-Carbenium-Ionen als reaktive Zwischenstufen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 360-366 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Evidence for 4-Homocubyl Carbenium Ions as Reactive Intermediates4-(Hexafluoroisopropoxy)homocubane (6) is the main product of the thermolysis reaction of N-(4-homocubyl)-N-nitrosoacetamide (9) and of the solvolysis reaction of 4-homocubyl bromide (5) in hexafluoro-2-propanol. This is experimental evidence for 4-homocubyl carbenium ions as intermediates in both reactions. The solvolysis rate of 4-homocubyl bromide at 120°C in the same solvent (k1120°C=1.3 · 10-7s-1) by far exceeds that of 1-norbornyl bromide which does not react at a detectable rate under these conditions. According to force field calculations the strain enthalpy is increasing by as much as 66 kcal · mol-1 in the ionisation of 4-homocubyl bromide. Therefore nonclassical stabilization of the 4-homocubyl carbenium ion is postulated.
    Notes: Bei der Thermolyse von N-(4-Homocubyl)-N-nitrosoacetamid (9) und bei der Solvolyse von 4-Homocubylbromid (5) in Hexafluor-2-propanol entsteht 4-(Hexafluorisopropoxy)homocuban (6) als Hauptprodukt. Dies beweist das Auftrete von 4-Homocubyl-Carbenium-Ionen als Zwischenstufen beider Reaktionen. Die Solvolysegeschwindigkeit von 4-Homocubylbromid bei 120°C in Hexafluor-2-propanol (k1120°C = 1.3 · 10-7 s-1) ist wesentlich höher als die von 1-Norbornylbromid, dessen Solvolyse unter diesen Bedingungen nicht nachweisbar ist. Da die Ionisation von 4-Homocubylbromid nach Kraftfeldrechnungen mit 66 kcal · mol-1 Ansteigen an Spannungsenthalpie verbunden ist, wird für das 4-Homocubyl-Carbenium-Ion eine nichtklassische Stabilisierung angenommen.
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    Übergangsmetall-substituierte Phosphane, Arsane und Stibane, XXXIII. (Brommethyl)bis[(trimethylsilyl)methyl]arsan: Darstellung und Metallierung zu Komplexen mit η1 - oder η2-koordiniertem Arsinomethyl-Liganden (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 348-359 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Substituted Phosphanes, Arsanes, and Stibanes, XXXIII. (Bromomethyl)bis[(trimethylsilyl)methyllarsane: Synthesis and Metalation to Complexes with η1- or η2-Coordinated Arsinomethyl LigandThe pyrolysis of the trialkyldibromoarsorane (Me3SiCH2)3AsBr2 (1) under reduced pressure yields the (bromomethyl)arsane (Me3SiCH2)2AsCH2Br (2) with Me3SiBr elimination via the intermediate formation of the bromodialkylmethylenearsorane Br(Me3SiCH2)2As=CH2. 2 reacts with Na[M(CO)3Cp] (M=Mo, W) to give the transition metal substituted arsanes Cp(CO)3M-CH2As(CH2SiMe3SiMe3)2 (3a,b). These undergo cyclisation with loss of CO and formation of Cp(CO)2M[η2 CH2As(CH2SiMe3)2] (4a,b), the first complexes with an η2-bound arsinomethyl unit, either spontaneously (3a) or upon ultraviolet irradiation or prolonged standing at room temperature (3b). MeI quaternizes the arsane 3b to give the metalated arsonium salt [Cp(CO)3W - CH2As(Me)(CH2SiMe3)2]I (5). The NMR spectra indicate fluxional behaviour for the chiral metallacycles 4a, b. It is caused by a rapid change of the configuration at the metal centre, for which a mechanism, involving a rotation of the dihapto-coordinated ligand about an axis defined by the metal and the centre of the As—C(M) bond, is suggested.
    Notes: Die Pyrolyse des Trialkyldibromarsorans (Me3SiCH2)3AsBr2 (1) bei reduziertem Druck liefert unter Me3SiBr-Eliminierung über die intermediäre Stufe eines Bromdialkylmethylenarsorans Br(Me3SiCH2)2)2As=CH2 das (Brommethyl)arsan (Me3SiCH2)2AsCH2Br (2). Dieses reagiert mit Na[M(CO)3Cp] (M=Mo, W) zu den Übergangsmetall-substituierten Arsanen Cp(CO)3M-CH2As(CH2SiMe3)2 (3a,b), welche sich spontan (3a) bzw. bei UV-Bestrahlung oder längerem Stehenlassen bei Raumtemperatur (3b) unter CO-Verlust in Cp(CO)2M[η2-CH2As(CH2SiMe3)2] (4a,b), die ersten Komplexe mit η2-gebundener Arsinomethyl-Einheit, umwandeln. MeI quartärisiert das Arsan 3b zum metallierten Arsoniumsalz [Cp(CO)3W - CH2As(Me)(CH2SiMe3)2]I (5). Die NMR-Spektren zeigen für die chiralen Metallacyclen 4a, b fluktuierendes Verhalten an. Als Mechanismus für den dafür verantwortlichen schnellen Konfigurationswechsel am Zentralmetall wird die Rotation des dihapto-koordinierten Liganden um eine durch das Metall und den Mittelpunkt der As—C(M)-Bindung verlaufende Achse vorgeschlagen.
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    Darstellung und Strukturbestimmung von Ammoniak-Phosphorpentafluorid (1/1) (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 367-374 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and X-Ray Structure Analysis of Ammonia-Phosphorus Pentafluoride (1/1)The adduct H3N · PF5 (1) is obtained in 8% yield from the reaction of NH3 with PF5, in 41% yield, however, from HF and (F2PP=N)3. The x-ray structure analysis shows only slightly distorted octahedral geometry at phosphorus with a P—N bond length of 1.842 Å. 14N-H, 14N-P-F(cis), and 14N-P coupling constants are found in the 1H, 19F, and 31P NMR spectra.
    Notes: Das Addukt H3N · PF5 (1) wird in 8proz. Ausbeute bei der Reaktion von H3N mit PF5 und in 41proz. Ausbeute durch Umsetzung von wasserfreiem HF mit (F2P=N)3 erhalten. Die Röntgenstrukturanalyse ergibt eine nur wenig verzerrte oktaedrische Geometrie mit einem P—N-Bindungsabstand von 1.842 Å. Aus den 1H-, 19F- und 31P-NMR-Spektren können die Kopplungen 14N-H, 14N-P-F(cis) und 14N-P entnommen werden.
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    Anodische Fragmentierung O-acylierter α-Hydroxycarbonsäuren (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 375-388 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anodic Fragmentation of O-Acylated α-Hydroxy Carboxylic AcidsDepending on the degree of substitution at the α-carbon atom, the electrolyses of O-acylated α-hydroxy carboxylic acids 1 yield products of fragmentation (aldehydes or ketones 5) and products derived from acylium ions 4 in concurrence with simple anodic substitution products (acylales, amides, and imides, respectively). Dioxiranyl cations 2 are involved as intermediates. The fragmentation of the dioxiranyl cation 2 is investigated by semiempirical MINDO/3 calculations (Scheme 1).
    Notes: Die Elektrolyse O-acylierter α-Hydroxycarbonsäuren 1 liefert über Dioxiranyl-Kationen 2 als Zwischenstufen je nach Substitutionsgrad am α-Kohlenstoffatom von 1 Fragmentierungsprodukte (Aldehyde oder Ketone 5) und Folgeprodukte von Acylium-Ionen 4 in Konkurrenz zu einfachen anodischen Substitutionsprodukten (Acylale bzw. Amide und Imide). Die Fragmentierung des Dioxiranyl-Kations 2 (Schema 1) wurde mit semiempirischen Methoden (MINDO/3) untersucht.
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    Untersuchungen zur Reaktivität von Metall-π-Komplexen, XXXVII. Brückenaustauschreaktionen an zweikernigen μ-(Cyclopentadienyl)-dipalladium-Komplexen: Synthese sandwich-artiger heterometallischer Pd2Cr- und Pd2Mo-Cluster (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2914-2926 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Reactivity of Metal π-Complexes, XXXVII. Bridge-Exchange Reactions with Dinuclear μ-(Cyclopentadienyl)-dipalladium Complexes: Synthesis of Sandwich-like Heterometallic Pd2Cr and Pd2Mo ClustersThe dimetal sandwich complexes (C5H5)2Pd2(PR3)2 (I) react with carboxylic acids R'CO2H and thiols R'SH by exchanging one cyclopentadienyl bridge to yield the compounds (C5H5)(OCOR')-Pd2(PR3)2 (1-6) and (C5H5)(SR')Pd2(PR3)2 (7-12). Displacement of the cyclopentadienyl and not of the allyl ligand also occurs in the reactions of (C5H5)(2-RC3H4)Pd2[P(iPr)3]2 (II) with R'CO2H and R'SH with formation of the dinuclear μ-(allyl)-dipalladium compounds (2-RC3H4)-(OCOR')Pd2[P(iPr)3]2 (13-23) and (2-RC3H4)(SR')Pd2[P(iPr)3)2 (24-27). The reaction of (C5H5)-(2-MeC3H4)Pd2(P(iPr)3]2 (IIa) with terephthalic acid leads to the tetranuclear complex 28. The trinuclear heterometallic clusters 29, 30 are obtained by bridge-exchange starting from (C5H5)(OCO-tBu)Pd2[P(iPr)3]2 (4) and Na[C5H5Cr(CO)3] or Na[C5H5Mo(CO)3], respectively.
    Notes: Die Dimetall-Sandwichkomplexe (C5H5)2Pd2(PR3)2 (I) reagieren mit Carbonsäuren R'CO2H und Thiolen R'SH unter Austausch einer Cyclopentadienyl-Brücke zu den Verbindungen (C5H5)-(OCOR')Pd2(PR3)2 (1-6) und (C5H5)(SR')Pd2(PR3)2 (7-12). Bei den Umsetzungen der Komplexe (C5H5)(2-RC3H4)Pd2[P(iPr)3]2 (II) mit R'CO2H und R'SH wird ebenfalls der Cyclopentadienyl- und nicht der Allyl-Ligand verdrängt, so daß die zweikernigen μ-(Allyl)-dipalladium-Verbindungen (2-RC3H4)(OCOR')Pd2[P(iPr)3]2 (13-23) und (2-RC3H4)(SR')Pd2[P(iPr)3]2 (24-27) entstehen. Die Reaktion von (C5H5)(2-MeC3H4)Pd2[P(iPr)3]2 (IIa) mit Terephthalsäure führt zu dem Vierkernkomplex 28. Durch Brückenaustausch sind aus (C5H5)(OCO-tBu)Pd2[P(iPr)3]2 (4) und Na[C5H5Cr(CO)3] bzw. Na[C5H5Mo(CO)3] die dreikernigen heterometallischen Cluster 29, 30 zugänglich.
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  • 90
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    Reaktionsprodukte aus N,N-Bis(chlormethyl)carboxamiden und Diaziridinen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 2947-2949 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction Products from N,N-Bis(chloromethyl)carboxamides and DiaziridinesSpiro[cyclohexane-1,3′-diaziridine] (1) reacts with N,N-bis(chloromethyl)carboxamides (2) to form pentacyclic ditriazolidino-s-hexahydrotetrazines 7.
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  • 91
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    Monoozonolyse von 2,3-Dimethylbutadien in Pentan und in Methanol (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 409-415 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Monoozonolysis of 2,3-Dimethylbutadiene in Pentane and in Methanol2,3-Dimethylbutadiene (1) was attacked predominantly at only one double bond by a deficient amount of ozone in pentane or in methanol. In pentane, an α,β-unsaturated ozonide (4) was formed, which was further converted into an α,β-dibromoozonide (2) and into an α,β-epoxyozonide (6), respectively. Ozonolysis of 1 in methanol afforded an α,β-unsaturated methoxy hydroperoxide (8) and formaldehyde as well as a joint coproduct (9) of the latter two fragments.
    Notes: 2,3-Dimethylbutadien (1) wurde von einem Unterschuß an Ozon in Pentan oder in Methanol überwiegend nur an einer Doppelbindung angegriffen. In Pentan entstand ein α,β-ungesättigtes Monoozonid (4), aus welchem ein α,β-Dibromozonid (2) und ein α,β-Epoxyozonid (6) hergestellt wurden. Ozonolyse von 1 in Methanol ergab ein α,β-ungesättigtes Methoxyhydroperoxid (8) und Formaldehyd sowie ein gemeinsames Folgeprodukt (9) dieser Fragmente.
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    1,3-Dipolare Cycloadditionen, 89. Neue Beiträge zur Chemie des Diphenylnitrilimins (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3062-3070 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Dipolar Cycloadditions, 89. New Contributions to the Chemistry of DiphenylnitrilimineMethyl propiolate, tetrolate, and phenylpropiolate combine with diphenylnitrilimine (1) to afford regioisomeric cycloadducts; the preferential orientation shifts in the sequence given from the pyrazole-5-carboxylic ester to the 4-carboxylic ester. Corresponding isomer ratios substantiate the occurrence of 1 in the reaction of (α-chlorobenzylidene)phenylhydrazine + triethylamine and in the photolysis or thermolysis of 2,5-diphenyltetrazole. - Chloroethylenes and 1 furnish 5-chloropyrazolines which eliminate HCl. - The sodium salt of (α-nitrobenzylidene)phenylhydrazine likewise is a source of 1. The electrophilic propiolic ester gives rise to an adduct mixture which is richer in methyl 1,3-diphenylpyrazole-4-carboxylate than that characteristic of 1, thus suggesting a second reaction pathway.
    Notes: Propiolsäure-, Tetrolsäure- und Phenylpropiolsäureester treten mit Diphenylnitrilimin (1) zu den beiden regioisomeren Cycloaddukten zusammen, wobei sich die Vorzugsorientierung in der genannten Folge vom Pyrazol-5-carbonsäureester zum -4-carbonsäureester verschiebt. Gleiche Isomerenverhältnisse belegen das Auftreten von 1 bei der Reaktion des (α-Chlorbenzyliden)-phenylhydrazins mit Triethylamin sowie bei der Photolyse oder Thermolyse des 2,5-Diphenyltetrazols. - Chlorierte Ethylene vereinigen sich mit 1 zu 5-Chlorpyrazolinen, die HCl abgeben. - Auch das Natriumsalz des (α-Nitrobenzyliden)phenylhydrazins bietet eine Quelle für 1. Abweichungen vom üblichen Orientierungsverhalten beobachtet man bei Propiolsäure-methylester; höhere Gehalte am 1,3-Diphenylpyrazol-4-carbonsäureester weisen auf einen zusätzlichen Reaktionsweg.
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    Asymmetrische Michael-Additionen. Regio-, diastereo- und enantioselektive Alkylierungen der Enamine aus β-Tetralonen und (S)-2-(Methoxymethyl)pyrrolidin („Prolinolmethylether“) durch ω-Nitrostyrole (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3086-3096 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Michael Additions. Regio-, Diastereo-, and Enantioselective Alkylations of the Enamines from β-Tetralones and (S)-2-(Methoxymethyl)pyrrolidine („Prolinol Methyl Ether“) by ω-Nitrostyrenesβ-Tetralones with various substitutents (CH3, NO2, OCH3, OCH2O, Cl) in 1-, 5-, 6-, 7- and 8-position are added to ω-nitrostyrenes (2) through enamines (1) derived from (S)-2-(methoxymethyl)pyrrolidine. Hydrolysis of the primary adducts (3) yields (35-55%) β-tetralones 4 alkylated in the 3-position. These are all 〉 90% diastereomerically and 75-99% optically pure (see u-4 and Table 1). From results of earlier investigations it is inferred, that the present reaction occurs with relative topicity lk, ul-1, 4 (see 6), i.e. that the products 4 have (3S, 1′R)-configuration. This is compatible with the 1H NMR and CD spectra of the isolated products of type 4.
    Notes: β-Tetralone mit den verschiedensten Substituenten (CH3, NO2, OCH3, OCH2O, Cl) in 1-, 5-, 6-, 7- und 8-Stellung werden über die Enamine (1) mit (S)-2-(Methoxymethyl)pyrrolidin an ω-Nitrostyrole (2) addiert, was nach Hydrolyse der Primär-Addukte 3 mit 35-55% Ausbeute zu den in 3-Stellung alkylierten β-Tetralonen 4 führt. Diese Hauptprodukte der Reaktion bestehen zu über 90% (ds) aus den u-Diastereomeren mit 75-99% Enantiomerenüberschuß (ee), siehe Formel 4 und Tab. 1. Die Resultate früherer Untersuchungen lassen erwarten, daß auch die hier beschriebene Reaktion mit relativer Topizität lk, ul-1,4 abläuft (siehe 6), daß also die Produkte 4 (3S, 1′R)-Konfiguration besitzen. Dies ist mit den 1H-NMR- und CD-Spektren der Produkte vom Typ 4 vereinbar.
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  • 94
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    Nucleophile Addition von Triorganozinn-Anionen an Kohlenstoffdisulfid, VI. Substitutionsreaktionen an Tetracarbonyl(triphenylstannandi-thiocarboxylato-S,S′)mangan(I) mit σ-Donorliganden der V. Hauptgruppe (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3071-3085 
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nucleophilic Addition of Triorganotin Anions to Carbon Disulfide, VI. Substitution Reactions of Tetracarbonyl(triphenylstannanedithiocarboxylato-S,S′)manganese(I) with σ-Donor Ligands of Main Group VThe facial tricarbonyl complexes (CO)3-(L)MnS2CSnPh3 (2a: L = P(OPh)3, 2b: L = P(OMe)3, 2c: L = PPh3, 2d: L = AsPh3, 2e: L = SbPh3, 2f: L = P(c-C6H11)3) are obtained by thermal substitution of the tetracarbonylmanganese chelate complex (CO)4MnS2CSnPh3 (1) with VB donor ligands. With more bulky phosphane ligands, the meridional complexes 3f (L = P(c-C6H11)3, and 3g (L = Ph2PCH2CH2PPh2 (dppe)) are formed by photolytic and thermal substitution, respectively. 3f and g rearrange easily to the more stable facial isomers 2f and 5c. By extended thermal (L = P(OPh)3, P(OMe)3) or by photolytic reactions (L = PPh3, AsPh3, SbPh3) of 1 with the given ligands, the trans-disubstituted products 4a-e are obtained. The rearrangement 4d→2d was followed by UV spectroscopy and found to proceed in the stoichiometric ratio 3:2 with k = (1.14 ± 0.01)·10-4 s-1 (t = 25°C). Complexes with a monodentate stannanedithiocarboxylate ligand are synthesized by substitution of 1 with bidentate ligands (5c: L = dppe, 5d: L = dipy) or by metathesis of substituted carbonylmetal halides (5b′: L = PPh3, M = Re; 5e: 2 L = P(OPh)3 M = Mn). The results show that the thermal substitution is consistent with a dissociative mechanism while the photolytic substitution is assumed to require a ring opening of the chelate ligand.
    Notes: Durch thermische Substitution des Tetracarbonylmangan-Chelatkomplexes (CO)4MnS2CSnPh3 (1) mit Donorliganden der V. Hauptgruppe erhält man die facialen Tricarbonylkomplexe (CO)3-(L)MnS2CSnPh3 (2a: L = P(OPh)3, 2b: L = P(OMe)3, 2c: L = PPh3, 2d: L = AsPh3, 2e: L = SbPh3, 2f: L = P(c-C6H11)3). Dagegen werden mit sterisch anspruchsvolleren Phosphanliganden die meridionalen Komplexe 3f (L = P(c-C6H11)3, photochemisch) und 3g (L = Ph2PCH2CH2PPh2 (dppe), thermisch) gebildet, die sich leicht in die stabileren facialen Isomeren 2f bzw. 5c umlagern. Durch längere thermische Reaktion (L = P(OPh)3, P(OMe)3) oder photochemische Umsetzung (L = PPh3, AsPh3, SbPh3) von 1 mit den angegebenen Liganden entstehen die trans-Disubstitutionsprodukte 4a-e. Die Rückbildung 4d→2d wurde UV-spektroskopisch verfolgt und läuft im stöchiometrischen Verhältnis 3:2 mit k = (1.14 ± 0.01)·10-4 s-1 (t = 25°C) ab. Komplexe mit einzähnig koordiniertem Stannandithiocarboxylat-Liganden lassen sich durch Substitution von 1 mit zweizähnigen Liganden (5c: L = dppe, 5d: L = dipy) oder durch direkte Umsetzung substituierter Carbonylmetallhalogenide (5b′: L = PPh3, M = Re; 5e: 2 L = P(OPh)3, M = Mn) darstellen. Die Ergebnisse zeigen, daß sich die thermische Substitution mit einem Dissoziationsmechanismus vereinbaren läßt, während bei der photochemischen Substitution eine Ringöffnung des Chelatliganden anzunehmen ist.
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    Derivate des 1,4-Diborabenzols: Über die erste ionische 1,4-Diboratabenzol-Verbindung und Über übergangsmetall-Komplexe von 1,4-Dibora-2,5-cyclohexadienen (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3115-3127 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Derivatives of 1,4-Diborabenzene: The First Ionic 1,4-Diboratabenzene Compound and Transition Metal Complexes of 1,4-Dibora-2,5-cyclohexadienesThe 1,4-dibora-2,5-cyclohexadiene FcB[CH=CH]2BFc (1h) (FcH = Fe(C5H5)2) is reduced by sodium amalgam to produce diamagnetic Na2[FcB[C2H2]2BFc] containing a novel 6π-electron anion. 17 transition metal complexes (4-8) of Co, Rh, Ni, and Pt with 1,4-dibora-2,5-cyclohexadiene ligands L (L = RB[C2H2]2BR) are described. Complexes with R = Fc and CH3O are obtained by complexation of 1h, its dianion, or CH3OB[CH=CH]2BOCH3 (1c), respectively. Other substituents at boron including R = H, CH3, C6H5, Cl, and (CH3)2N may be introduced by nucleophilic substitution. In all cases the 1,4-dibora-2,5-cyclohexadiene ligands are η6-bonded. Attempted Friedel-Crafts acetylation of (C5R5)M{CH3B[C2H2]2BCH3} (M = Co, R = H and M = Rh, R = CH3) (5f, 6f) effects ring-member substitution to give the corresponding cationic borabenzene derivatives [(C5R5)M(4-CH3C5H4BCH3)]+ (e.g. 10+).
    Notes: Das 1,4-Dibora-2,5-cyclohexadien FcB[CH=CH]2BFc (1h) (FcH = Fe(C5H5)2) wird durch Natriumamalgam zu diamagnetischem Na2[FcB[C2H2]2BFc] reduziert, welches ein neuartiges 6π-Elektronen-Anion enthält. 17 übergangsmetall-Komplexe (4-8) von Co, Rh, Ni und Pt mit 1,4-Dibora-2,5-cyclohexadien-Liganden L (L = RB[C2H2]2BR) werden beschrieben. Komplexe mit R = Fc und CH3O werden durch Komplexierung von 1h, seinem Dianion oder von CH3OB[CH=CH]2BOCH3 (1c) erhalten. Andere Substituenten am Bor wie R = H, CH3, C6H5, Cl und (CH3)2N lassen sich durch nucleophile Substitution einführen. Die 1,4-Dibora-2,5-cyclohexadien-Liganden sind in allen Fällen η6-gebunden. Der Versuch der Friedel-Crafts-Acetylierung von (C5R5)M{CH3B[C2H2]2BCH3} (M = Co, R = H und M = Rh, R = CH3) (5f, 6f) bewirkt Ringgliedsubstitution und ergibt die entsprechenden kationischen Borabenzol-Derivate [(C5R5)M(4-CH3C5H4BCH3)]+ (z. B. 10+).
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    Übergangsmetall-Carbin-Komplexe, LXVIII. Synthese und Struktur neuartiger zweikerniger Biscarbin-Komplexe des Chroms, Molybdäns und Wolframs mit verbrückenden Phenylthio-, Arylseleno-, Halogeno- und Pseudohalogeno-Liganden (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3152-3166 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Carbyne Complexes, LXVIII. Synthesis and Structure of Novel Binuclear Biscarbyne Complexes of Chromium, Molybdenum, and Tungsten with Bridging Phenylthio-, Arylseleno-, Halogeno-, and Pseudohalogeno LigandsPentacarbonyl[(diethylamino)(ethoxy)carbene]molybdenum (1) reacts with boron trifluoride to give a very unstable product which is supposed to be pentacarbonyl[(diethylamino)carbyne]-molybdenum tetrafluoroborate (2). Low temperature reaction of 2 with bromide, iodide, and thiocyanate yields the neutral trans-substituted carbyne complexes trans-X(CO)4MoCNEt2 (4a-c) [X = Br (a), I (b), SCN (c)] cyanate and 4-(trifluoromethyl)phenylselenolate afford the compounds (μ-X)2[(CO)3MoCNEt2]2 (5d, f) [X = OCN (d), 4-CF3C6H4Se (f)] which are members of a new class of binuclear biscarbyne complexes. Analogues 5a-c, g-l are prepared from the carbyne complexes trans-X(CO)4MCNR2 (4a-c, g-l) on warming in solution. The corresponding complex 5e (X = N3, M = W, R = C2H5) is obtained by the reaction of pentacarbonyl[(diethylamino)carbyne]tungsten tetrafluoroborate (6) with azide. The structures of 5b, d, e, g are ensured by X-ray analyses.
    Notes: Pentacarbonyl[(diethylamino)(ethoxy)carben]molybdän (1) reagiert mit Bortrifluorid zu einem sehr instabilen Produkt, bei dem es sich vermutlich um Pentacarbonyl[(diethylamino)carbin]-molybdän-tetrafluroborat (2) handelt. Wird 2 bei tiefer Temperatur mit Bromid, Iodid und Thiocyanat umgesetzt, erhält man die neutralen trans-substituierten Carbinkomplexe trans-X(CO)4MoCNEt2 (4a-c) [X = Br (a), I (b), SCN (c)] demgegenüber ergeben Cyanat und 4-(Trifluormethyl)phenylselenolat die Verbindungen (μ-X)2[(CO)3MoCNEt2]2 (5d, f) [X = OCN (d), 4-CF3C6H4Se (f)] als Vertreter einer neuen Klasse von zweikernigen Biscarbin-Komplexen. Die dazu analogen Verbindungen 5a-c, g--l werden dargestellt, indem man die Carbinkomplexe trans-X(CO)4MCNR2 (4a-c, g-l) in Lösung aufwärmt. Der entsprechende Komplex 5e (X = N3, M = W, R = C2H5) wird bei der Umsetzung von Pentacarbonyl[(diethylamino)carbin]-wolfram-tetrafluoroborat (6) mit Azid erhalten. Der Aufbau von 5b, d, e, g ist durch Röntgenstrukturanalysen gesichert.
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    Aromatizität als Funktion des Ionenpaarcharakters: Akzeptor-substituierte Cyclononatetraenyl-Anionen, Enolat-Anionen mit variablen Ladungsverteilungen und ungewöhnlichen konformativen Eigenschaften (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3167-3190 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aromaticity as a Function of the Ion Pair Character: Acceptor-substituted Cyclononatetraenyl Anions, Enolate Anions with a Variable Charge Distribution, and Unusual Conformational PropertiesIn contrast to normal enolates like 1⊖Li⊕ the conformational properties of the acceptor-substituted cyclononatetraenyl anions 2a⊖, 2b⊖, 2c⊖, and of the dianion 2d⊖, are strongly determined by the gegenion, the solvent, and the temperature. Thus, the contact ion pairs 2b⊖Li⊕ and 2a⊖Na⊕ have properties similar to the ones of the nonafulvene silyl enol ether 7, as shown by the 1H- and 13C NMR spectra and by the facile valence isomerization to the corresponding dihydroindenes. Contrary to the contact ion pairs, the solvent separated ion pairs 2′a⊖ Na⊕(THF, - 45°C), 2′a⊖ K⊕(THF), 2′b⊖ Li⊕(THF, HMPT), 2′c- Li⊕(THF), and 2′d⊖ 2Li⊕-(THF), e.g., are substituted [9]annulene anions, again revealed by the 1H and 13C NMR spectra and by the reluctance towards valence isomerization. Therefore, without assoziation of the gegenion (especially of the small Li⊕) to the potential enolate oxygen atom, the negative charge is preferentially delocalized in the [9]annulene anion ring; 13C NMR spectra and MNDO calculations even indicate that the orthogonal conformation of the [9]annulene anion ring and the substituent is the most favourable one! Comparable ion pair equilibria have been noticed before; the unusual conformational changes transforming reversibly an olefinic into an aromatic compound, which are connected with these ion pair effects, however, are without precedence. Likewise, „orthogonal enolates“ are unknown.
    Notes: Im Gegensatz zu normalen Enolaten wie 1⊖Li⊕ werden die konformativen Eigenschaften der akzeptor-substituierten Cyclononatetraenyl-Anionen 2a⊖, 2b⊖, 2c⊖ sowie des Dianions 2d⊖ ganz maßgeblich von Gegenion, Lösungsmittel und Temperatur bestimmt. So verhalten sich die Kontaktionenpaare 2b⊖Li⊕ und 2a⊖Na⊕ ähnlich wie der Nonafulvensilylenolether 7: 1H- und 13C-NMR-Spektren sind vergleichbar und die Valenzisomerisierung zu den entsprechenden Dihydroindenen ist nahezu gleich schnell. Diesen olefinischen Nonafulveneigenschaften der Kontaktionenpaare stehen diejenigen der solvens-getrennten Ionenpaare entgegen: 2′a⊖ Na⊕(THF, -45°C), 2′a⊖ K⊕(THF), 2′b⊖ Li⊕(THF, HMPT), 2′c⊖ Li⊕(THF) und 2′d⊖ 2Li⊕(THF), z. B., sind substituierte [9]Annulen-Anionen, was sich wiederum aus den 1H- und 13C-NMR-Spektren sowie aus der Stabilität gegenüber einer Valenzisomerisierung ergibt. Ohne Assoziation des Gegenions (insbesondere von Li⊕) an den potentiellen Enolatsauerstoff bleibt also die negative Ladung bevorzugt im [9]Annulen-Anionring verteilt; 13C-Spektren und MNDO-Rechnungen besagen sogar, daß Substituent und anionischer Neunring bei orthogonaler Anordnung die stabilste Konformation aufweisen! Ionenpaar-Gleichgewichte ähnlichen Ausmaßes sind durchaus bekannt; die außergewöhnlichen konformativen Veränderungen (reversible Umwandlung Olefin ⇌ Aromat), die mit den Ionenpaareffekten bei den substituierten Cyclononatetraenyl-Anionen verbunden sind, haben jedoch keine Präzedenz. „Orthogonale Enolate“ kennt man bislang ebenfalls nicht.
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  • 98
    Electronic Resource
    Electronic Resource
    Chirale SFeCoM-Cluster: Darstellung, Nebenreaktionen und Nachweis der Chiralität (1982)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 3224-3242 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chiral SFeCoM Clusters: Synthesis, Side Reactions, and Proof of ChiralityFrom SFeCo2(CO)9 (1) via the intermediates SFeCo2(CO)8—AsMe2—MCp(CO)3 (3, M = Cr, Mo, W) by the Co—As elimination method the chiral clusters SFeCoMCp(CO)8 (8, M = Cr, Mo, W) could be obtained. From such reactions other clusters resulted too, of which one with a SCo2Mo(μ-AsMe2) framework (10b) and one with a SCo2W(μ-AsCoAs) framework (12) were identified by crystal structure analyses. The chirality of the intermediates 3 as well as that of PMe2Ph derivatives of the clusters 1, 8, and 10 could be proved NMR-spectroscopically by the diastereotopism of the AsMe2- and PMe2 methyl groups, respectively.
    Notes: Aus SFeCo2(CO)9 (1) ließen sich über die Zwischenstufen SFeCo2(CO)8—AsMe2—MCp(CO)3 (3, M = Cr, Mo, W) nach der Co—As-Eliminierungsmethode die chiralen Cluster SFeCoMCp(CO)8 (8, M = Cr, Mo, W) gewinnen. Bei solchen Reaktionen entstanden auch andere Cluster, von denen einer mit SCo2Mo(μ-AsMe2)-Gerüst (10b) und einer mit SCo2W(μ-AsCoAs)-Gerüst (12) durch Kristallstrukturanalyse identifiziert wurden. Sowohl in den Zwischenstufen 3 als auch in PMe2Ph-Derivaten der Cluster 1, 8 und 10 ließ sich die Chiralität NMR-spektroskopisch über die Diastereotopie der AsMe2-bzw. PMe2-Methylgruppen nachweisen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19821151003
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  • 99
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    Electronic Resource
    Reaktionen von Carbonsäurechloriden mit cyclischen Kohlenwasserstoffen unter dem Einfluß ionisierender Strahlung (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 500-508 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Carboxylic Acid Chlorides with Cyclic Hydrocarbons under the Influence of Ionizing RadiationUnder the influence of ionizing radiation on carboxylic acid chlorides/cycloalkane solutions, acylcycloalkanes are formed besides the related aldehydes and bicycloalkanes. The reaction is studied thoroughly for the benzoyl chloride/cyclohexane system. A kinetic scheme is proposed in which ionisation of the hydrocarbon and the subsequent reactions of the cations and electrons are the primary steps. In particular, acyl radicals are postulated as intermediates. The preparative applicability of the reaction is discussed. (3-Methylbenzoyl)cyclopentane is prepared from 3-methylbenzoyl chloride/cyclopentane and propionylcyclooctane from propionyl chloride/cyclooctane.
    Notes: Unter dem Einfluß ionisierender Strahlung auf Lösungen von Carbonsäurechloriden in cyclischen Kohlenwasserstoffen entstehen Acylcycloalkane neben den entsprechenden Aldehyden und Bicycloalkanen. Am Beispiel des Systems Benzoylchlorid/Cyclohexen wird die Reaktion eingehend untersucht und ein kinetisches Schema vorgeschlagen. In diesem Schema sind die Ionisierung des Kohlenwasserstoffs und die nachfolgenden Reaktionen der Kationen und Elektronen die primären Schritte. Insbesondere werden Acylradikale als Zwischenprodukte postuliert. Die präparative Anwendbarkeit der Reaktion wird diskutiert. Aus 3-Methylbenzoylchlorid/Cyclopentan werden (3-Methylbenzoyl)cyclopentan und aus Propionylchlorid/Cyclooctan Propionylcyclooctan dargestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160210
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    Eine neue Synthese und Reaktionsverhalten von (Aminoethinyl)sulfiden (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 509-513 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Novel Synthesis and Reactions of Aminoethynyl SulfidesReaction of the alkynide 2 with sulfur provides ready access to aminoethynyl sulfides 5 with different second substituents on the sulfide sulfur atom. Hydrolysis and cycloadditions with diphenylketene, phenyl isocyanate, or tosyl isothiocyanate prove the S-alkyl derivatives 5a, b to be typical ynamines, whereas amine addition to the silylthio compound 5c takes a different course.
    Notes: Über die Reaktion des Alkinids 2 mit Schwefel lassen sich in einfacher Weise (Aminoethinyl)sulfide 5 mit verschiedenen Zweitsubstituenten am Sulfid-Schwefel erhalten. In der Hydrolyse und in Cycloadditionen mit Diphenylketen, Phenylisocyanat oder Tosylisothiocyanat erweisen sich die S-Alkyl-Derivate 5a, b als typische Inamine, während die Amin-Addition an die Silylthio-Verbindung 5c einen abweichenden Verlauf nimmt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160211
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