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  • Organic Chemistry  (3,492)
  • Inorganic Chemistry  (3,415)
  • 1985-1989  (6,907)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 2-6 
    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).
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 10-13 
    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.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 89-91 
    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.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 7-9 
    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
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 178-179 
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 170-173 
    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.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 174-177 
    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.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 192-196 
    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.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 183-191 
    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.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 202-208 
    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.
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  • 11
    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.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 1-1 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 13
    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.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 57-62 
    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.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 16
    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.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 99-120 
    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.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 137-141 
    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.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 21
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989) 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 22
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 249-250 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 23
    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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  • 24
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    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 284-292 
    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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  • 25
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    Chirality 1 (1989), S. 94-95 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 26
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    Chirality 1 (1989), S. 98-98 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 27
    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.
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  • 28
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    Chirality 1 (1989), S. 97-97 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 29
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    Chirality 1 (1989), S. 121-126 
    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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  • 30
    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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  • 31
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    Chirality 1 (1989), S. 154-160 
    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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  • 32
    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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    Chirality 1 (1989), S. 167-169 
    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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  • 34
    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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    Chirality 1 (1989), S. 178-179 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 36
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    Chirality 1 (1989), S. 246-248 
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 37
    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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  • 38
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Structure, and Catalytic Activity of μ-(Alkylthio)-dicarbonyl-μ-chloro-bis(tri-tert-butylarsane)dirhodium ComplexesTetracarbonyl-di-μ-chloro-dirhodium (1) reacts with tri-tert-butylarsane (2) and alkyl trimethylsilyl sulfides (4) to give complexes [Rh2(CO)2(AstBu3)2Cl(SR)] (5a-c). The complexes 5b and c with the surface active trialkoxysilyl groups [R=(MeO)3SiCH2CH2, (MeO)3SiCH2CH2CH2] are bound to fused silica support. The X-ray structural analysis of[Rh2(CO)2(AstBu3)2Cl(StBu)] (5a) indicates a cis-configuration of the tri-tert-butylarsane ligands. The new complexes catalyze the hydroformylation of cyclohexene, and the isomerization of allylbenzene (8) into cis- and trans-β-methylstyrene (9). The soluble complex 5a was shown to be an extremely effective olefin hydrogenation catalyst, whereas the supported complexes 6b and c were completely inactive in this process.
    Notes: Durch Umsetzung von Tetracarbonyl-di-μ-chloro-dirhodium (1) mit Tri-tert-butylarsan (2) und Alkyl(trimethylsilyl)sulfiden (4) werden die Komplexe [Rh2(CO)2(AstBu3)2Cl(SR)] (5a-c) dargestellt. Die Komplexe 5b und c mit Trialkoxysilyl-Gruppen [R=(MeO)3SiCH2CH2, (MeO)3SiCH2CH2CH2] werden auf Silicagel fixiert. Die Röntgenstrukturanalyse von [Rh2(CO)2- (AstBu3)2Cl(StBu)] (5a) zeigt das Vorliegen von cis-konfigurierten Tri-tert-butylarsan-Gruppen. Die neuen Komplexe katalysieren die Hydroformylierung von Cyclohexen und die Isomerisierung von Allylbenzol (8) zu cis- und trans-β-Methylstyrol (9). Während lösliches 5a die Hydrierung von Olefinen katalysiert, sind die Heterogenkatalysatoren 6b und c hierbei völlig inaktiv.
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  • 39
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2757-2776 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bridgehead Olefinic Isomers of Triquinacene: Derivatives of Tricyclo[5.2.1.04,10]deca-1,5,8- and -1,6,8-trieneBridgehead halides 12 and 13 of triquinacene (2) with soft nucleophiles undergo a syn-stereoselective SN2′ reaction forming derivatives of tricyclo[5.2.1.04,10]deca-1,5,8-triene 15 and 17, respectively, and of tricyclo[5.2.1.04,10]deca-1,6,8-triene 18. The relative stability of these bridgehead olefins is discussed with regard to force field calculations as well as semiempirical MNDO calculations.
    Notes: Brückenkopf-Mono- 12 und -Dihalogenide 13 des Triquinacens (2) reagieren mit weichen Nucleophilen im Sinne einer syn-stereoselektiven SN2′-Reaktion zu Derivaten des Tricyclo[5.2.1.04,10]-deca-1,5,8-triens 15 bzw. 17 und des Tricyclo[5.2.1.04,10]deca-1,6,8-triens 18. Die relative Stabilität dieser Brückenkopf-Olefine wird anhand von Kraftfeld-Rechnungen sowie semiempirischen MNDO-Rechnungen diskutiert.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2746-2756 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stability Constants and Thermodynamic Values for the Formation of 1:1- and 2:1-Complexes of Crown Ethers with Alkali and Alkaline-earth Ions in MethanolThe determination of stability constants and thermodynamic values for the reaction of crown ethers with alkali-, alkaline-earth ions, and the silver ion was achieved by calorimetric titration in methanol. Through modification of the experimental conditions it is possible to measure separately the formation of 1:1- and 2:1-complexes (ratio of ligand to cation). With the exception of Ag+ and Ca2+ all ions examined form both kinds of complexes with the various 15 C 5 ligands. The complex stabilities are influenced by enthalpic and entropic contributions. 18 C 6 and DC 18 C 6, having a bigger diameter than 15 C 5, show a definite increase of the stability of 1:1-complexes. Only the Cs+ ion with the largest radius forms 2:1-complexes. A good agreement is found with values determined potentiometrically for the 1:1- and 2:1-complex formation of Na+.
    Notes: Die Komplexstabilitäten und thermodynamischen Werte für die Reaktion von Kronenethern mit Alkali-, Erdalkali-Ionen und dem Silber-Ion in Methanol wurden mittels kalorimetrischer Titrationen bestimmt. Durch Veränderung der experimentellen Bedingungen ist es möglich, sowohl die Bildung von 1:1- als auch 2:1-Komplexen (Verhältnis von Ligand zu Kation) getrennt voneinander zu messen. Mit Ausnahme von Ag+ und Ca2+ bilden alle untersuchten lonen beide Arten von Komplexen mit den verschiedenen 15 K 5-Liganden. Die Komplexstabilitäten werden von enthalpischen und entropischen Faktoren beeinflußt. 18 K 6 und DC 18 K 6, die einen größeren Durchmesser als 15 K 5 besitzen, zeigen einen deutlichen Anstieg der Stabilität der 1:1-Komplexe. 2:1-Komplexe bildet nur noch das Cs+ -Ion mit dem größten Radius. Ein Vergleich mit potentiometrisch bestimmten Daten für die 1:1- und 2:1-Komplexbildung von Na+ zeigt gute Übereinstimmung.
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  • 41
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2777-2788 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anodic Oxidation of O-Benzoylated α-Hydroxyacetic Acids - A Contribution to the Reactivity of Anodic Oxidated Carboxylate Ions - “Umpolung”Anodic oxidation of O-benzoylated α-hydroxyacetic acid 1 at graphite electrodes in methanol leads to the corresponding mixed acylals 2 and methyl benzoates 3. The rate 2:3 depends on the substitution of the aromatic ring and can be correlated to Hammett's σ-values.
    Notes: Bei der anodischen Oxidation O-benzoylierter α-Hydroxyessigsäuren 1 an Graphitelektro-den in Methanol entstehen die zugehörigen gemischten Acylale 2 und die entsprechenden Benzoesäure-methylester 3. Das Produktverhältnis 2:3 ist abhängig von der Substitution des Aromaten und läßt sich mit den Hammettschen σ-Werten korrelieren.
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  • 42
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2789-2797 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclopentadienyl-substituted Germylenes and Stannylenes as Complex LigandsTransition metal complexes of chloro(pentamethylcyclopentadienyl)germylene and -stannylene with pentacarbonylchromium and -tungsten bound to the 4B-element (3a, b, 5a, b) are available by alkylation of the ylide complexes Cl2(THF)El→M(CO)5 (El=Ge, Sn; M=Cr, W, 1a, b, 4a, b). X-Ray structure studies on the germylene complex Me5C5(Cl)-Ge→ W(CO)5 (3b) show that involving the lone-pair of the 4B-element in a metal-metal bond changes the distorted h5-Me5C5 coordination of the uncomplexed germylene to a highly symmetrical h2-structure.
    Notes: Übergangsmetallkomplexe des Chlor(pentamethylcyclopentadienyl)germylens und -stannylens mit am 4B-Element gebundener Pentacarbonylchrom- bzw. -wolframeinheit (3a, b, 5a, b) werden durch Alkylierung der Ylidkomplexe Cl2(THF)El→M(CO)5 (El=Ge,Sn; M=Cr, W, 1a, b, 4a, b) erhalten. Röntgenographische Untersuchungen am Germylenkomplex Me5C5(Cl)Ge→W(CO)5 (3b) zeigen, daß sich die Inanspruchnahme des “lone-pair” am 4B-Element in einem Wechsel der verzerrten h5-Me5C5-Koordination im freien Germylen zu einer hochsymmetrischen h2-Koordination äußert.
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  • 43
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 52. Oxidative Ring Opening of Tetra-tert-butyltetrahedrane. - Crystal and Molecular Structure of Tetra-tert-butylcylobutenylium IonsOxidative ring opening of tetra-tert-butyltetrahedrane yields cyclobutenylium ions of type 4 or 6. Their spectroscopic properties, but especially the crystal structure determination of 4h and 6c, show the characteristics expected for homocyclopropenylium salts. Because of 1,3-bonding interactions the ions are folded (4h: 37.3°, 6c: 36.4°), the 1,3-distances across the four-membered ring are short (4h: 1.806 Å, 6c: 1.833 Å).
    Notes: Bei der oxidativen Ringöffnung von Tetra-tert-butyltetrahedran entstehen Cyclobutenylium-Salze vom Typ 4 oder 6. Deren spektroskopische Eigenschaften, vor allem aber röntgenographische Strukturbestimmungen von 4h oder 6c, rechtfertigen es, diese Verbindungen als Homocyclopropenylium-Salze zu benennen. Die Ionen sind aufgrund von 1,3-bindenden Wechselwirkungen stark gefaltet (4h: 37.3°, 6c: 36.4°), der 1,3-Abstand im Vierring ist kurz (4h: 1.806 Å, 6c: 1.833 Å).
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2811-2821 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tetrafluoro-1,2-ethanedisulfenyl Dichloride - a Precursor for new Sulfur-Nitrogen-Carbon Heterocycles1,3,2-Dithiazolidines (3a-c) are obtained by reaction of the title compound CISCF2CF2SCI 1 with disilylated amines (Me3Si)2NR (R=Me, Ph, SiMe3). Reaction with (Me3-SiNR)2SO2 (R=Me, SiMe3) yields 1,3,5,2,4-trithiadiazepanes 4a, b, whereas N,N′-disilylated urea leads to the dithiadiazepanon 5. CISCF2CF2SSCI and SO2[N(SiMe3)2]2 react to yield the eight-membered tetrahiadiazocane 6. Using the dilution principle, with disilylated piperazine 7 in a molar ratio of 1:1 the sixteen-membered ring 9 is formed, which contains two piperazine units within the ring skeleton. The crystal structure of 1,3,5,2,4-trithiadiazepane-tetraphenylphosphonium chloride 10 is reported. 4b reacts with 1 to yield 11 in which a ten-membered ring is bridged by an SO2 group. By changing the reaction conditions a product of twice the molecular weight is formed, for which a tricyclic system with a central fourteen-membered ring 13 is proposed.
    Notes: Die Titelverbindung CISCF2CF2SCI 1 reagiert mit disilylierten Aminen (Me3Si)2NR (R=Me, Ph, SiMe3) glatt zu 1,3,2-Dithiazolidinen (3a-c). Bei der Umsetzung mit (Me3SiNR)2SO2 (R=Me, SiMe3) werden die 1,3,5,2,4-Trithiadiazepane 4a, b erhalten; mit N,N′-disilyliertem Harnstoff bildet sich das 1,5,2,4-Dithiadiazepanon 5. CISCF2CF2SSCI und SO2[N(SiMe3)2]2 reagieren zum achtgliedrigen 1,2,4,6,3,5-Tetrathiadiazocan 6. Durch Anwendung des Verdünnungsprinzips wird mit disilyliertem Piperazin 7 im Molverhältnis 1:1 der sechzehngliedrige Ring 9 synthetisiert, welcher zwei Piperazineinheiten im Ringgerüst enthält. Von 1,3,5,2,4-Trithiadiazepan-Tetraphenylphosphoniumchlorid 10 wird die Röntgenstrukturanalyse mitgeteilt. 4b reagiert mit 1 zu 11; hier liegt ein zehngliedriger Ring vor, der durch eine SO2-Gruppe überbrückt ist. Bei veränderter Reaktionsführung erhält man ein Produkt der doppelten Molekülmasse, dem eine tricyclische Struktur zugeschrieben wird, die einen zentralen vierzehngliedrigen Ring enthält (13).
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2852-2857 
    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 1,3-Dithietan-2-one 1,1-DioxideOzonolysis of 2-(benzoylmethylene)-1,3-dithietane 1,1-dioxide (7), prepared via oxidation of 2-(benzoylmethylene)-1,3-dithietane (6), yielded 1,3-dithietan-2-one 1,1-dioxide (5) as the first 1,3-dithietane with an α-oxosulfone structure. Diethyl (1,3-dithietan-2-ylidene)malonate S,S-dioxide (2) did not react with ozone. 5 can be regarded as a potential sulfene precursor. However, in the pyrolysis of 5 sulfene could not be detected so far.
    Notes: Ozonolyse von 2-(Benzoylmethylen)-1,3-dithietan-1,1-dioxid (7), dargestellt durch Oxidation von 2-(Benzoylmethylen)-1,3-dithietan (6), ergab 1,3-Dithietan-2-on-1,1-dioxid (5) als erstes 1,3-Dithietan mit α-Oxosulfonstruktur. (1,3-Dithietan-2-yliden)malonsäure-diethylester-S,S-dioxid (2) setzte sich dagegen nicht mit Ozon um. 5 kann als potentieller Sulfen-Bildner angesehen werden. Bei der Pyrolyse von 5 konnte jedoch bislang kein Sulfen nachgewiesen werden.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2974-2992 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloadditions of 1-(4-Methoxyphenyl)-2,2-dimethylvinyl Cation to Olefins1-Bromo-1-(4-methoxyphenyl)-2-methyl-1-propene (1) reacts with cyclohexene, cycloheptene, (Z)-cyclooctene and the silver salts AgBF4, via the vinyl cation 2 by cycloaddition to form the cyclobutenes 7b-d. Cyclobutene 8 is obtained from (Z)- and (E)- and (E)-2-butene. Besides the cyclobutene derivatives, the isomeric cyclopropane compound 10d is also formed in the reaction of 1 with (Z)-cyclooctene under the same conditions, with cyclopentene only the cyclopropane derivative is formed. Copper (I) triflate-olefin complexes can be used in place of silver slats to generate the vinyl cation 2, whereby cyclobutenes 7 are formed preferably. - In contrast to vinyl bromide 1, 1-(4-methoxyphenyl)-2-methyl-1-propenyl triflate (5) reacts with cyclopentene, cyclohexene, cyloheptene, (Z)- and (E)-cyclooctene to give mostly the corresponding cyclopropane derivatives 10. The stereoisomeric cyclopropyl compounds 19 are obtained from (Z)- and (E)-2-butene. - The mechanisms of silver-catalysed and silver-free cycloaddition reactions are discussed.
    Notes: 1-Brom-1-(4-methoxyphenyl)-2-methyl-1-propen (1) reagiert mit Cyclohexen, Cyclohepten, (Z)-Cycloocten und den Silbersalzen AgBF4 bzw. AgSbF6 über das Vinylkation 2 unter Cycloaddition überwiegend zu den Cyclobutenen 7b-d. Mit (Z)- und (E)-2- Buten wird das Cyclobuten 8 erhalten. Bei der Umsetzung von 1 unter den gleichen Bedingungen entsteht mit Cyclopenten das Cyclopropanderivat 10a, mit (Z)-Cycloocten entsteht neben dem Cyclobutenderivat 7d die isomere Cyclopropanverbindung 10d. An Stelle der Silbersalze können auch Kupfer(I)-triflat-Olefin-Komplexe zur Erzeugung des Vinylkations 2 verwendet werden, wobei ebenfalls bevorzugt die Cyclobutene 7 erhalten werden. - Im Gegensatz zum Vinylbromid 1 reagiert das 1-(4-Methoxyphenyl)-2-methyl-1-propenyl-triflat (5) mit Cyclopenten, Cyclohexen, Cyclohepten und (Z)- bzw. (E)-Cycloocten überwiegend zu den entsprechenden Cyclopropanderivaten 10. Mit (Z)- und (E)-2-Buten werden die stereoisomeren Cyclopropylverbindungen 19 erhalten. - Die Mechanismen der silbersalzkatalysierten und silberfreien Cycloadditionsreaktionen werden diskutiert.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
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    Topics: Chemistry and Pharmacology
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3011-3019 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Experiments to Form Enediazenium Salts(2-Alkoxyvinyl)diazenium salts 9 and 14 are obtained by O-alkylation of glyoxal- (4) and methylglyoxal monodimethylhydrazone (13), resp., with alkyl trifluoromethanesulfonates. Bromination of N-(trimethylsilyl)enehydrazines 16 and 18 in pentane leads to the formation of solid, hydrophilic substances, for which the structures of enediazenium salts 19, α-bromohydrazones 20, or ammonium salts 21 are discussed. These compounds react with nucleophiles (alcohols, amines, thiols, and indole) to give hydrazones 24a-i substituted at C-2.
    Notes: Glyoxal- (4) und Methylglyoxal-monodimethylhydrazon (13) werden durch Trifluormethansulfonsäure-alkylester am Sauerstoff zu (Alkoxyvinyl)diazeniumsalzen 9 bzw. 14 alkyliert. N-Silylierte Enhydrazine 16 und 18ergeben mit Brom in Pentan feste, hydrophile Verbindungen, für die die Strukturen von Endiazeniumsalzen 19 oder α-Bromhydrazonen 20 bzw. Ammoniumsalzen 21 diskutiert werden. Diese Verbindungen addieren Alkohole, Amine, Thiole sowie Indol als Nucleophile am C-Atom 2 unter Bildung der Hydrazone 24a-i.
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  • 49
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3166-3171 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,3-Dithienium- and 1,3-Dithiolenium Salts, IV. 1,3-Dithian-2-ylium Tetrafluoroborates - New Agents for the Synthesis of 1-DeuterioaldehydesThe 1,3-dithian-2-ylium tetrafluoroborates 3 react in good yields with sodium borohydride (4) to give the 1,3-dithianes 6 and with sodium borodeuteride (5) to form the precursors 7 of 1-deuterated aldehydes 8. Three 1-deuterioaldehydes 8 are synthesized exemplarily by dethioacetalization of 7.
    Notes: Die 1,3-Dithian-2-ylium-tetrafluoroborate 3 reagieren in guten Ausbeuten mit Natriumborhydrid (4) zu den 1,3-Dithianen 6 und mit -deuterid (5) unter Bildung der Vorläufer 7 von 1-deuterierten Aldehyden 8. Exemplarisch werden drei 1-Deuterioaldehyde 8 durch Dethioacetalisierung von 7 synthetisiert.
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  • 50
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3196-3204 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Small Rings, 54. CyclopentadienoneCyclopentadienone (1) can be generated by photolysis or pyrolysis of several precursors and isolated in an argon matrix. It dimerizes even on thawing of the matrix (38 K). The IR and UV spectroscopic properties of 1 are discussed.
    Notes: Cyclopentadienon (1) kann aus mehreren Vorstufen photolytisch oder pyrolytisch erzeugt und in einer Argonmatrix bei 10 K isoliert werden. Es dimerisiert bereits beim Auftauen der Matrix (38 K). Die IR- und UV-spektroskopischen Eigenschaften von 1 werden beschrieben.
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  • 51
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3188-3195 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organometallic Compounds of Iridium and Rhodium, XXIII. Chelate Phosphane-Substituted Iridaheterocycles of the Form (chel-P3)When treated with chelate phosphanes chel-P3, aryl iridium(I) compounds of the type Ir(CO)[C6H4-nMen-CH3-(2)](PPh3)2 readily undergo PPh3 substitution, CO insertion, and oxidative benzyl C-H addition to give metallaheterocyclic complexes of formula fac-(Chel-P3) 1-4) (C6H4-nMen=C6H4, C6H3Me-(6), C6H2Me2-(4,6); chel-P3=PhP[(CH2)3PPh2]2, MeP[(CH2)3PPh2]2, PhP[(CH2)2PPh2]2, MeC(CH2-PPh2)3). The cyclic iridium(III) species have been investigated by IR, 1H, and 31P NMR spectroscopy as well as by a single crystal X-ray diffraction analysis of fac-[PhP(CH2CH2-CH2PPh2)2] 1a).
    Notes: Aryliridium(I)- Verbindungen des Typs Ir(CO)[C6H4-nMen-CH3-(2)](PPh3)2 reagieren mit Chelatphosphanen chel-P3 unter PPh3-Substitution, CO-Insertion und oxidativer Benzyl C - H-Addition spontan zu metallaheterocyclischen Iridaindanon-Spezies der Formel fac-(chel-P3)1 - 4) (C6H4-nMen=C6H4, C6H3Me-(6), C6H2Me2-(4, 6); chel-P3=PhP[(CH2)3PPh2]2, MeP[(CH2)3PPh2]2, PhP[(CH2)2PPh2]2 MeC(CH2PPh2)3). Die cyclischen Iridium(III)-Verbindungen wurden spektroskopisch (IR, 1H- und 31P-NMR) sowie röntgenographisch (fac-[PhP(CH2CH2CH2PPh2)2]-, 1 a) untersucht.
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  • 52
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3217-3226 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Substituted Electron-rich N-Sulfonyl-1-azabutadienesThe syntheses of alkylthio- und arylthio-substituted electron-rich N-sulfonyl-1-azabutadienes 3a - e, 5a - d, and 10a - c, of dialkylamino-substituted N-sulfonyl-1-azabutadienes 6a - g, and the sulfoxide 11 are described.
    Notes: Es wird über die Synthesen der alkylthio- bzw. arythiosubstituierten elektronenreichen N-Sulfonyl-1-azabutadiene 3a - e sowie 5a - d und 10a - c, über die dialkylaminosubstituierten N-Sulfonyl-1-azabutadiene 6a - g und das Sulfoxid 11 berichtet.
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  • 53
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3205-3216 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (tert-Butylimino)[tert-butyl(trimethylsilyl)amino]borane, an Aminoiminoborane, and its ReactionsThe title compound (1b) was prepared by gas-phase elimination of FSiMe3 from the corresponding diaminoborane as a distillable liquid, storable at -30°C, dimerizing at room temperature. Additions to the more unsaturated BN-bond are typical for 1b. Protic reagents are added to give the aminoboranes 3a - c. The aminoboranes 3d - h are formed by ethylo-, azido-, or chloroboration or by azidosilation of 1b, respectively. The chloroboration can be followed by the novel formation of the diazadiboretidines 2e - g. Iminoboranes give a ring closure with 1b, the diazadiboretidines 2b,h being formed. The addition of the CO-bond of aldehydes to 1b yields the oxazaboretidines 4a - c. The [2 + 3]-cycloaddition products 5a,b are isolated by the reaction of 1b with azide- or nitrone-type 1,3-dipolar systems. The borane 1b behaves as a dienophile towards cyclopentadiene with the bicyclic molecule 6 as the product. By X-ray analysis, the central ring-unit of 2f turns out to be a BNBN-rhombus with the acute angles at the N-atoms.
    Notes: Die Titelverbindung (1b) erhält man als destillierbare, bei -30°C lagerfähige, bei Raumtemperatur dimerisierende Flüssigkeit durch Gasphaseneliminierung von FSiMe3 aus dem entsprechenden Diaminoboran. Typisch für 1b sind Additionen an die stärker ungesättigte BN-Bindung. Protonenaktive Stoffe addieren sich zu den Aminoboranen 3a - c. Durch Ethylo-, Azido- oder Chloroborierung sowie durch Azidosilierung erhält man die Aminoborane 3d - h. Die Chloroborierung kann mit einer neuartigen Bildung der Diazadiboretidine 2e - g einhergehen. Iminoborane addieren sich an 1b zu den Diazadiboretidinen 2b,h. Die Addition der CO-Bindung von Aldehyden führt zu den Oxazaboretidinen 4a - c. 1,3-Dipolare Verbindungen vom Azid- bzw. Nitrontyp ergeben die Fünfring-Verbindungen 5a,b. Mit Cyclopentadien reagiert 1b als Dienophil zum Bicyclus 6. Für die Verbindung 2f ergibt sich als zentrale Baueinheit röntgenographisch eine BNBN-Raute mit spitzen Winkeln an den N-Atomen.
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  • 54
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3241-3247 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloadducts from 3-Imino-3H-1,2,4-dithiazoles and Nitriles: Conditions of Preparation and StructureA series of (thiocarbamoylimino)-1,2,4-thiadiazolines (2) was prepared by ring-opening cycloaddition from some imino-1,2,4-dithiazoles (1) and different nitriles. The structure of 2j was determined by X-ray analysis and compared with an isomeric thiadiazolidine (3).
    Notes: Eine Reihe von (Thiocarbamoylimino)-1,2,4-thiadiazolinen (2) wurde durch ringöffnende Cycloaddition aus einigen Imino-1,2,4-dithiazolen (1) und verschiedenen Nitrilen hergestellt. Von 2j wurde eine Röntgenstrukturanalyse angefertigt und mit der eines isomeren Thiadiazolidins (3) verglichen.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3275-3286 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: High Pressure Experiments, XIII. Reaction of tert-Butyl Isonitrile and of Toluene with Bicyclo[2.2.1]heptene (Norbornene) at High PressureAt pressure of about 10 kbar tert-butyl isonitrile reacts with bicyclo[2.2.1]heptene (norbornene) in low yield to give many products of which addition compounds 2 - 11 were identified. With pure toluene exo-2-benzylbicyclo[2.2.1]heptane (10) was found. With oxygen containing toluene also exo-2,3-epoxybicyclo[2.2.1]heptane (2) was isolated. The structure of methanopyrroloindole 6 is confirmed by an X-ray structure analysis.
    Notes: Unter einem Druck von etwa 10 kbar verbindet sich tert-Butylisonitril mit Bicyclo-[2.2.1]hepten (Norbornen) in geringer Ausbeute zu mehreren Produkten, von denen die Verbindungen 2 - 11 aufgeklärt werden konnten. Mit reinem Toluol entsteht in 41proz. Ausbeute exo-2-Benzylbicyclo[2.2.1]heptan (10). Mit sauerstoffhaltigem Toluol wird auch exo-2,3-Epoxybicyclo[2.2.1]heptan (2) erhalten. Von Methanopyrroloindol 6 wurde eine Röntgenstrukturanalyse durchgeführt.
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  • 56
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Medium and Large Rings, XI. Bicyclo[n.2.2]alkenes from Bridged Oxepins - Synthesis of Dimethyl 3,6-Pentanooxepin-4,5-dicarboxylate and Dimethyl 6,9-Dihydro[5]paracyclophane-7,8-dicarboxylateA new approach to bicyclo[5.2.2]undec(adi)enes and bicyclo[6.2.2]dodecene derivatives, starting from cycloheptanone and cyclooctanone is described. Key steps of this synthesis are the conversion of 3,4-pentano- and -hexanofuran to the β,β′-bridged oxepins 2 and the transannular addition of bromine to 2. The dibromides 3a and 3b can be debrominated to give 3c and 3d in high yield.
    Notes: Ein neuer Zugang zu Bicyclo[5.2.2]undec(adi)enen und Bicyclo[6.2.2]dodecen-Derivaten, ausgehend von Cycloheptanon und Cyclooctanon, wird beschrieben. Schlüsselschritte dieser Synthese sind die Überführung von 3,4-Pentano- und -Hexanofuran in die β,β′-überbrückten Oxepine 2 und eine transannulare Addition von Brom an 2. Die Dibromide 3a und 3b lassen sich in hohen Ausbeuten zu 3c und 3d entbromieren.
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  • 57
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3299-3310 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbohydrate-Model Compounds, I. Kinetic and Thermodynamic Effects in Acetal Formation of Enantiomerically Pure ThiolactolsThe synthesis of the enantiomerically pure thiolactol 1 is described. Depending on reaction conditions either (R)-2 or (S)-2 reacts with preference in acetal formation with racemic 1-phenylethanol (rac-2).
    Notes: Die Herstellung des enantiomerenreinen Thiolactols 1 wird beschrieben. Bei der Acetalisierung mit racemischem 1-Phenylethanol (rac-2) reagiert je nach Wahl der Reaktionsbedingungen entweder (R)-2 oder (S)-2 bevorzugt.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3332-3349 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aliphatic Liquid Crystals, 2. Some Nematic Derivatives of all-trans-PerhydrophenanthreneA stereoselective synthesis of the all-trans-7-alkylperhydro-2-phenanthrenols 15a - f in 11 steps and 28 liquid crystalline esters 16 of 15a - f are described, additionally some further derivatives of 7-alkylperhydro-2-phenanthrenol. An X-ray structure analysis of ester 16ec is reported.
    Notes: Die stereoselektive Synthese der all-trans-7-Alkylperhydro-2-phenanthrenole 15a - f in 11 Stufen und 28 flüssigkristalline Ester 16 von 15a - f werden beschrieben, daneben einige weitere Derivate der 7-Alkylperhydro-2-phenanthrenole. Vom Ester 16ec wurde eine Röntgenstrukturanalyse durchgeführt.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3408-3412 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of Lead(II) by Aza Crown Ethers and Cryptands in MethanolThe stability of PbII complexes with the mono- and bicyclic ligands 1 - 5 in methanol was determined by potentiometric titrations using an ion-selective lead(II) electrode. Reaction enthalpies ΔH were measured by calorimetric titrations. Substitution of the protons at the nitrogen atoms of aza crown 1b by the long decyl chains in 1d leads to a great increase in ΔH, whereas the complex stability is scarcely influenced. Benzo anellands (3, 4) reduce the ligand flexibility and cause a decrease in reaction enthalpies. The reaction entropies are nearly unchanged.
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  • 60
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition von Singulettsauerstoff und 4-Phenyl-4H-1,2,4-triazol-3,5-dion mit 7-substituierten 1,3,5-CyclooctatrienenDie Cycloadditionen von 7-substituierten (X; Y) 1,3,5-Cyclooctatrienen 3 (N3; H), 4 (OAc; H), 5 (OEt; OEt), 6 (Me; H) und 7 (iPr; H) mit Singulettsauerstoff (1O2) und 4-Phenyl-4H-1,2,4-triazol-3,5-dion (PTAD) wurden untersucht. Singulettsauerstoff reagierte mit diesen Cyclooctatrienen aus dem bicyclischen Valenzisomeren (Bicyclo[4.2.0]octa-2,4-dien) heraus zu den entsprechenden tricyclischen Endoperoxiden. Bicyclische Endoperoxide, ausgehend von monocyclischen Valenzisomeren (1,3,5-Cyclooctatrien), wurden lediglich bei den alkylsubstituierten Derivaten 6 (Me; H) und 7 (iPr; H) erhalten. Die Cyclcoaddition mit PTAD führte zu den bicyclischen und tricyclischen Urazolen, mit Ausnahme des Acetals 5 (OEt; OEt), welches nur das tricyclische Produkt gab. Das Bromderivat 2 reagierte weder mit 1O2 noch mit PTAD. Kontrollexperimente mit der Stammverbindung zeigten, daß die Cycloadditionsprodukte entsprechend den mono- und bicyclischen Valenzisomerenanteilen des Eduktgemisches erhalten wurden.
    Notes: The cycloaddition of the 7-substituted (X; Y) 1,3,5-cyclooctatrienes 3 (N3; H), 4 (OAc; H), 5 (OEt; OEt), 6 (Me; H), and 7 (iPr; H) with singlet oxygen (1O2) and 4-phenyl-4H-1,2,4-triazole-3,5-dione (PTAD) was investigated. Singlet oxygen gave with all cyclooctatrienes the corresponding tricyclic endoperoxides derived from the bicyclic valence isomers (bicyclo[4.2.0]octa-2,4-dienes). The corresponding bicyclic endoperoxides derived from the monocyclic valence isomers (1,3,5-cyclooctatriene) were only obtained for the alkyl-substituted derivatives 6 (Me; H) and 7 (iPr; H). PTAD cycloaddition led to both the bicyclic and tricyclic urazoles, except with the acetal 5 which gave only tricyclic product. The bromo derivative 2 did not react with 1O2 nor PTAD. Control experiments with the parent cyclooctatriene showed that the cycloaddition products were derived from the “static” amounts of the monocyclic and bicyclic valence isomers in the substrate mixture.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3413-3418 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Product of Decarboxylation of Hexahydrophthalic Anhydride: Structure and Spectroscopic PropertiesThe decarboxylation of some dicarboxylic anhydrides by catalytic influence of tertiary amines occurs at surprisingly low temperature (T≥80°C). The product 12, formed from two molecules of hexahydrophthalic anhydride 6 with loss of one molecule of carbon dioxide, has been isolated and characterized by spectroscopic investigations and X-ray structure analysis.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3419-3423 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [2 + n]-Cycloadditions of [Bis(trimethylsilyl)methylene][(trimethylsilyl)ethynyl]phosphane[2 + n]-Cycloadditions of phosphaalkene 1 with sulfur, selenium, 2,3-dimethylbutadiene, diphenyldiazomethane, and trimethylsilyl azide leading to 2, 3, 11, 14, and 15 are reported.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 298-312 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Lewis Acidity of Nickel(0), II. Methylenetriorganylphosphorane Complexes of Nickel(0)Methylenetriorganylphosphoranes R3P = CH2 (R = CH3, C6H5) react with Ni(CDT) and Ni(C2H4)3 to form the (methylenetriorganylphosphorane)(alkene)nickel(0) complexes (R3PCH2)Ni(CDT) (R = CH3, 2) and (R3PCH2)Ni(C2H4)2) (R = CH3, C6H5, 4, 5). On treatment with CO the ethene complexes give the known carbonyl complexes (R3PCH2)Ni(CO)3 (R = CH3, C6H5, 9, 10) in pure form. 2 and 4 decompose at room temperature to give Me3PNi(CDT) and Me3PNi(C2H4)2; cyclopropane is produced in the presence of ethene.  -  The stability of the CH2—Ni0 bond in the methylenetriorganylphosphorane complexes falls in the series Ni(CO)3 〉 Ni(C2H4)2 〉 Ni(CDT), corresponding to declining Lewis acidity of the nickel atom. 13C NMR evidence indicates that in the same sequence the P—CH2 bond also becomes weakened. The thermally induced elimination of methylene shows that the nickel bonded methylene group has appreciable carbenoid character.
    Notes: Methylentriorganylphosphorane R3P = CH2 (R = CH3, C6H5) reagieren mit Ni(CDT) und Ni(C2H4)3 zu den (Methylentriorganylphosphoran)(alken)nickel(0)-Komplexen (R3PCH2) Ni(CDT) (R = CH3, 2) und (R3PCH2)Ni(C2H4)2(R = CH3, C6H5, 4, 5). Die Ethen-Komplexe ergeben mit CO die bereits bekannten Carbonyl-Komplexe (R3PCH2)Ni(CO)3(R = CH3, C6H5, 9, 10) in reiner Form. 2 und 4 gehen bei Raumtemperatur in Me3PNi(CDT) und Me3PNi(C2H4)2 über, wobei sich in Gegenwart von Ethen Cyclopropan bildet.  -  Die Stabilität der CH2—Ni0-Bindung in den Methylentriorganylphosphoran-Komplexen verringert sich mit der in der Reihe Ni(CO)3 〉 Ni(C2H4)2 〉 Ni(CDT) abfallenden Lewis-Acidität des Nickels. Aus den 13C-NMR-Spektren ist ableitbar, daß sich in gleicher Sequenz auch die P—CH2-Bindungsordnung vermindert. Die thermisch induzierte Methylen-Abspaltung läßt auf einen carbenoiden Charakter der an Nickel(0) gebundenen Methylengruppen schließen.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 313-322 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Lewis Acidity of Nickel(0), III. Alkali Metal Hydridotrialkylaluminate Complexes of Ni(CDT)Ni(CDT) reacts with hydridotrialkylaluminates of the alkali metals in ether/THF or ether/amine mixtures at temperatures below -50°C to form the temperature-sensitive compounds [MA(n-Donor)n]+[R3Al—H—Ni(CDT)]- (1-7) (MA = Li, Na; R = Me, Et, iBu). An Al—H—Ni three-centre bond is present in these complexes. On the basis of NMR data, the strength of the hydridoaluminate-nickel bond and the charge on nickel, caused by the hydridoaluminate residue, are compared with the corresponding characteristics of other ligand-Ni(CDT) complexes in which donor-acceptor σ-bonds are present.
    Notes: Ni(CDT)Abkürzungen: CDT = trans, trans, trans-1,5,9-Cyclododecatrien, COD = 1,5-Cyclooctadien, MA+ (solvatisiertes) Alkalimetall-Ion, PMDTA = N,N,N′,N″N″-Pentamethyldiethylentriamin, TMEDA = N,N,N′,N′-Tetramethylethylendiamin. reagiert mit Alkalimetall-hydridotrialkylaluminaten in Ether/THF-oder Ether/Amin-Mischungen als Lösungsmittel unterhalb von -50°C zu den thermisch labilen Verbindungen [MA(n-Donor)n]+[R3Al—H—Ni(CDT)]- (1-7) (MA = Li, Na; R = Me, Et, iBu). In diesen Komplexen liegt eine Al—H—Ni-Mehrzentrenbindung vor. Anhand NMR-spektroskopischer Daten lassen sich die Stärke der Hydridoaluminat-Nickel-Bindung und die Beladung des Nickels durch den Hydridoaluminat-Rest mit den Bindungsverhältnissen in anderen Ligand-Ni(CDT)-Komplexen mit Donor-Akzeptor-σ-Bindungen vergleichen.
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  • 65
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 370-379 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Reagents, XXIX. Synthesis, Stability, and Preparative Applications of (Triphenylplumbyl)methyllithium(Triphenylplumbyl)methyllithium (2), obtained from well accessible starting compounds by iodine-Li- or plumbyl-Li exchange, is applied as a reagent for the introduction of the (triphenylplumbyl)methyl group into alkyl halides, aldehydes, ketones, oxiranes, and organoelement halides.
    Notes: (Triphenylplumbyl)methyllithium (2), durch Iod-Li- oder Plumbyl-Li-Austausch mit Phenyllithium in Tetrahydrofuran aus gut zugänglichen Ausgangssubstanzen erhältlich, wird als Reagenz zur Einführung der (Triphenylplumbyl)methyl-Gruppe in Alkylhalogenide, Aldehyde, Ketone, Oxirane und Organoelementhalogenide angewandt.
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  • 66
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 397-400 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Reaction of 3-Iminophenoxazine with Ammonia and AminesPhenazines and phenoxazines are formed in the reaction of 3-iminophenoxazine with amines.
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  • 67
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 391-396 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Reagents, XXXI. Synthesis of (Iodomethyl)-and (Diiodomethyl)element Compounds of the Elements Si, Ge, Sn, PbVia Li—CH2—Hal or Li—CHHal2 (Hal = I, Br), respectively, the monohalides Ph3El—CH2—I (El = Si, Ge, Pb) and Ph3 Ge—CH2—Br have been obtained (49-74%) as well as the dihalides Ph3El—CHI2 (El = Si, Ge, Sn; 49-69%), Ph3Pb—CHI2 (9%), and Ph3Ge—CHBr2 (78%). These compounds are favourable starting materials for corresponding monolithium compounds. Some of them have found synthetic applications.
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  • 68
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 409-412 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 50. Unusual Dimerization of Tri-tert-butylcyclobutadieneThe dimerization of tri-tert-butylcyclobutadiene (2) does not lead to syn-dimer 4 but  -  as shown by a X-ray structure determination  -  via a two-step process to the unexpected anti-configurated dimer 5.
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  • 69
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 428-435 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diazadienes as Controlling Ligands in Homogeneous Catalysis, IX Catalytic Cyclotetramerization of Propynoic EstersPropynoic esters HC≡C—CO2R 2 react at low temperature in cyclohexane in the presence of precatalysts of the type of diazadiene-nickel(0) complexes 3 and 4 or diazadiene-nickel-(η2-alkyne) complexes such as 5b to give exclusively or preponderantly cyclooctatetraene tetracarboxylic esters 7. From 1H and 13C NMR data and by chemical methods a 1,3,6,8-substitution pattern (symmetry C2) is established.
    Notes: Propiolsäureester HC≡C—CO2R 2 lassen sich bei niedriger Temperatur in Cyclohexan an Präkatalysatoren vom Typ der Diazadien-Nickel(0)-Komplexe 3 bzw. 4 oder an Diazadien-Nickel-(η2-Alkin)-Komplexen wie 5b vollständig oder überwiegend zu Cyclooctatetraen-tetracarbon-säureestern 7 umsetzen. Aus 1H- und 13C-NMR-Daten sowie mit chemischen Methoden ergibt sich ein 1,3,6,8-Substitutionsmuster (Symmetrie C2).
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  • 70
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 444-449 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Palladium and Platinum(II) Complexes with the Anions of 6-Methyl-1,2,3-oxathiazin-4(3H)-one 2,2-Dioxide and N-2-PyrimidinylsulfanilamideWith the title ligand L = 3 the complexes K2[trans-PtCl2L2] (1) and K2[ML4] (M = Pt,Pd) (2, 4) have been obtained. The anion 5 of sulfadiazine and (nBu3P)(CI)PdCl2Pd(Cl)(PnBu3) give a dinuclear ligand bridged complex 6. The compounds are characterized by their IR and 1H NMR spectra. The structure of 1 was determined by X-ray structure analysis.
    Notes: Mit dem Titelliganden L = 3 werden die Komplexe K2[trans-PtCl2L2] (1) und K2[ML4] (M = Pt, Pd) (2, 4) erhalten. Das Sulfadiazin-Anion (5) bildet mit (nBu3P)(Cl)PdCl2Pd(Cl)(PnBu3) einen zweikernigen ligandverbrückten Komplex 6. Die Verbindungen werden spektroskopisch (IR, 1H-NMR) charakterisiert; die Struktur von 1 wird durch eine Röntgenstrukturanalyse bestimmt.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 785-795 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Entry to Alkylthio(trifluoroacetyl)furans by Way of Thermal [3 + 2]Cycloaddition Reactions of New Mesoionic 1,3-Oxathiol-4-ones to AlkynesAs cyclic carbonyl ylides, the novel 2-alkylthio-5-trifluoroacetyl-1,3-oxathiolylium-4-olates of type 1a-d combine with dimethyl acetylenedicarboxylate across the 2,5-position with formation of non-isolable primary adducts, which release COS to give the furandicarboxylic diesters 3a-d. Methyl propiolate reacts with 1a-c to produce mixtures of the regioisomeric furancarboxylic esters 4a-c and 5a-c, whose main components 4a-c are isolable. On the other hand, the reactions of phenylacetylene, 1-diethylaminopropyne, or (Z)-1-methoxy-1-buten-3-yne with 1a proceed with regiospecific formation of the furan derivatives 6, 7, or 8, respectively. The observed regioselectivities are qualitatively discussed on the basis of MO-perturbation theory.
    Notes: Als cyclische Carbonyl-ylide nehmen die neuen 2-Alkylthio-5-trifluoracetyl-1,3-oxathiolylium-4-olate vom Typ 1a-d in 2,5-Stellung Acetylendicarbonsäure-dimethylester unter Bildung nicht-isolierbarer Primäraddukte auf, die unter COS-Abspaltung Furandicarbonester 3a-d liefern. Mit Propiolsäure-methylester reagiert 1a-c zu Gemischen aus den regioisomeren Furancarbonestern 4a-c und 5a-c, deren Hauptkomponenten 4a-c isolierbar sind. Dagegen vereinigen sich Phenylacetylen, 1-Diethylaminopropin bzw. (Z)-1-Methoxy-1-buten-3-in mit 1a regiospezifisch zu den Furan-Derivaten 6, 7 bzw. 8. Die beobachteten Regioselektivitäten werden qualitativ auf der Basis der MO-Störungstheorie diskutiert.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 796-813 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Elektron-Donor-Acceptor-Verbindungen, XXXVI Chinone und Chinhydrone der [2.2]- und [3.3]Metaparacyclophan-ReihenDie isomeren Chinhydrone 1 und 2 sowie das Bis(chinon) 6 der [2.2]Metaparacyclophan-Reihe wurden synthetisiert. Vorstufe dieser Verbindungen war das Tetramethoxy[2.2]metaparacyclophan 3, das über 4 und 5 dargestellt wurde. Röntgen-Strukturanalysen von 1, 3 und 6 werden im Hinblick auf die sterische Spannung dieser Moleküle und die Donor-Acceptor-Orientierung in 1 diskutiert. Charge-transfer-Absorptionen von 1 und 2 werden ebenso behandelt wie der Circulardichroismus von 1, das in Enantiomere getrennt werden konnte.  -  Auf analogem Wege wurden die isomeren Chinhydrone 13 und 14 sowie das Bis(chinon) 15 der [3.3]Metaparacyclophan-Reihe dargestellt. Der Unterschied in der sterischen Spannung zwischen den [3.3]- und [2.2]-Metaparacyclophan-Reihen wird auf der Grundlage der Röntgen-Strukturanalyse von 13 diskutiert. Charge-transfer-Absorptionen von 13 und 14 werden angegeben.
    Notes: The isomeric quinhydrones 1 and 2 as well as the bis(quinone) 6 of the [2.2]metaparacyclophane series were synthesized. Precursor of these products was the tetramethoxy[2.2]metaparacyclophane 3 which was prepared via 4 and 5. X-ray structure analyses of 1, 3 and 6 are discussed with regard to the steric strain in these molecules and the donor-acceptor orientation in 1. Charge-transfer absorptions of 1 and 2 are reported as well as circular dichroism of 1 which was separated into enantiomers.  -  Following an analogous route the isomeric quinhydrones 13 and 14 as well as the bis(quinone) 15 of the [3.3]metaparacyclophane series were prepared. The difference in steric strain of the [3.3]- in comparison to the [2.2]metaparacyclophane series is discussed on the basis of an X-ray structure analysis of 13. Charge-transfer absorptions of 13 and 14 are reported.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 845-850 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Beweise gegen postulierte ungewöhnlich stabile Primärozonide von 1,4-Dichlor-2-butenenOzonolysen von cis- und trans-1,4-Dichlor-2-buten (1) in Methanol ergaben ca. äquimolare Anteile an 2-Chlor-1-methoxyethanol (6a) und 2-Chlor-1-methoxyethylhydroperoxid (7a) als Hauptprodukte sowie eine geringe Menge 2,2′-Dichlor-1-hydroxy-1′-methoxydiethylperoxid (8a). Ozonolyse von 1 in [D4]Methanol ergab die entsprechenden deuterierten Produkte 6c-8c. Die postulierte Existenz von ungewöhnlich stabilen Primärozoniden 2 wird widerlegt.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 952-963 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organic Syntheses with Transition Metal Complexes, 10. Metal Templates for the Syntheses of Carbocyclic Four- and Six-membered Rings from Isonitriles and Carbene ComplexesIsonitriles (R—NC, R = CH3, c-C6H11, tC4H9) react with carbene complexes (CO)5CrC(OCH3)R′ (R′ = CH3, C6H5) to give ketenimine complexes (CO)5Cr(R)N=C=C(OCH3)R′ 2a-f via insertion of the isonitrile into the M=C bond. The complexes 2 are isolated in crystalline form. On warming they dismutate to (CO)6Cr and (CO)4Cr complexes 3a-f of a 1,2-bis(imino)cyclobutane chelate ligand 4. The ligands 4 are generated in a template reaction by a hitherto unknown symmetrical [2 + 2]dimerisation of the ketenimines. 4 and the 1, 2-bis(hydroximino)cyclobutane 5 are obtained free of the metal by disengagement with H2O2/OH- or H2NOH, respectively. 3d, e easily isomerize to give bis(imino)tetrahydronaphthalenes 6d, e by expansion of the carbocyclic four- to the six-membered ring incorporating the phenyl group. Thermolysis of 6 leads to the formation of the 1,2-dihydronaphthaline derivative 7. The latter is also accessible in a one-pot synthesis from the carbene complex and the isonitrile without isolation of the intermediates 2, 3, and 6.
    Notes: Isonitrile (R — NC, R = CH3, c-C6H11, t-C4H9) reagieren mit Carbenkomplexen (CO)5CrC(OCH3)R′ (R′ = CH3, C6H5) unter Insertion der N = C- in die M = C-Bindung zu kristallin isolierbaren Keteniminkomplexen (CO)5Cr(R)N = C = C(OCH3)R′ 2a-f. Letztere sind sehr kondensations-freudig und dismutieren bei Abwesenheit eines Reaktionspartners zu (CO)6Cr und (CO)4Cr-Komplexen 3a-f, die ein 1,2-Bis(imino)cyclobutan 4 als Chelatligand enthalten. 4 bildet sich in einer Templatreaktion unter bisher unbekannter symmetrischer [2 + 2]-Dimerisierung des Keteniminliganden. Metallfreies 4 und ein davon abgeleitetes 1,2-Bis(hydroximino)cyclobutan 5 erhält man durch oxidative Zersetzung von 3 mit H2O2/OH- oder H2NOH. Die Bis(imino)cyclobutan-Komplexe 3d, e isomerisieren beim Erwärmen zu Bis(imino)tetrahydronaphthalin-Komplexen 6d, e durch Ringerweiterung des carbocyclischen Vier- zum Sechsring unter Einbeziehung des Aromaten. Die Thermolyse von 6e oder 6e′ gibt ein metallfreies 1,2-Dihydronaphthalin 7. Dieses kann in einer „Eintopfsynthese“ auch ohne Isolierung der Zwischenstufen 2, 3 und 6 direkt aus dem Carbenkomplex und dem Isonitril erhalten werden.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1008-1021 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Attempts to Prepare an Alkynyldiazonium SaltThe 2-bromo-1-chloroalkanal p-tosylhydrazones 11a, and b react with triethylamine as base to give the azoalkenes 12, of which (1-chloro-2-phenylethenyl)tosyldiazene (12b) is obtained as a crystalline material at room temperature. 12b reacts with SbCl5 at - 30 and - 70°C to form different diazonium salts, which are treated with nucleophiles such as methanol and water. The products obtained (Schemes 3 and 4) indicate the formation of the phenylethynyldiazonium salt 20, which is stable up to - 20°C. 20 adds nucleophiles like methanol or water as well as anisole at the C°C triple bond before releasing nitrogen.
    Notes: Die 2-Brom-1-chloralkanal-p-tosylhydrazone 11a und b reagieren mit Triethylamin als Base zu den Azoalkenen 12, von denen (1-Chlor-2-phenylethenyl)tosyldiazen (12b) als kristalline, bei Raumtemperatur stabile Verbindung erhalten wird. 12b reagiert mit SbCl5 bei - 30 und - 70°C zu verschiedenen Diazoniumsalzen, die mit nucleophilen Reaktionspartnern (Methanol und Wasser) umgesetzt werden. Die dabei erhaltenen Produkte (Schema 3 und 4) deuten auf die Entstehung des Phenylethinyldiazonioum-Salzes 20, das bis etwa - 20°C stabil ist. 20 addiert Nucleophile wie Methanol oder Wasser, aber auch Anisol an die C°C-Dreifachbindung, bevor eine Stickstoffabgabe erfolgt.
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  • 76
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Magnesium Acetylacetonate, Mg3[MeC(O)CHC(O)Me]6, and Magnesium (Diethoxyphosphinyl)acetonate, Mg3[(EtO)2P(O)CHC(O)Me]6- Trinuclear Chelate ComplexesThe title compounds 1 and 2 have been investigated by X-ray structure analysis and found to be trimeric. Each Mg atom is coordinated by six O atoms with a distorted octahedral array. The bridging of the central Mg atom with the terminal ones is achieved by common O atoms of the carbonyl groups. Whereas the preparation of magnesium (diethoxyphosphinyl)acetonate (2) has been reported previously, magnesium acetylacetonate (1) has been obtained for the first time by dehydration of Mg(acac)2(H2O)2.
    Notes: Röntgenuntersuchungen ergaben für die Titelverbindungen 1 und 2 trimere Strukturen. Jedes Mg-Atom ist von sechs O-Atomen verzerrt oktaedrisch koordiniert. Die Verbrückung des zentralen Mg-Atoms mit den endständigen erfolgt durch gemeinsame O-Atome der Car-bonyl-Gruppen. Magnesium-(diethoxyphosphinyl)acetonat (2) wurde nach Literaturangaben hergestellt, die Darstellung von Magnesium-acetylacetonat (1) erfolgte erstmals durch Entwässerung von Mg(acac)2(H2O)2.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3535-3550 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photolysis of 9-Azido-10-methyltriptycene. - Dimerization of a Severely Strained Bridgehead Imine via Distinct Cycloaddition RoutesIrradiation of a cyclohexane solution of the 9-azidotriptycene 1b affords molecular nitrogen and a mixture of products. By means of chromatography a dimer (S2-7), which is yellow in solution, and two colorless dimers (e.g. 3b and 5) of the intermediate bridgehead imine 2b are separated from this mixture. The structures of the photoproducts are elucidated by spectroscopic methods, particularly high field NMR. In addition, the structure 5 is proven by its rapid and quantitative photoisomerization to the colored dimer S2-7 the constitution 7 of which is confirmed by comparison with the anthrone anil 11 and hydrolysis to the (2-aminophenyl)anthrone 9. At room temperature rapid diastereotopomerization of the benzene rings of the 9,10-dihydroanthracene systems of S2-7 occurs via N-inversion (1H, 13C NMR). According to the proton spectrum in the absence of exchange ( - 60 °C), the colored product possesses S2 rather than C2 symmetry. The photoproducts are postulated to be derived from the initially formed azahomotriptycene 2b bearing a formal bridgehead CN double bond. This bridgehead imine first dimerizes to the isomeric 1,4-diradicals 13 and 14 which subsequently cyclize to the intermediate 15 and the [2 + 2] dimer 5, respectively. Photochemical [2 + 2]cycloelimination of 5 affords the dimer S2-7.
    Notes: Durch Bestrahlung des 9-Azidotriptycens 1b in Cyclohexan erhält man neben Stickstoff ein Gemisch, aus dem chromatographisch ein in Lösung gelbes Dimeres (S2-7) und zwei farblose Dimere (3b und 5) des intermediären Brückenkopfimins 2b isoliert werden. Die Strukturen dieser Photoprodukte werden auf spektroskopischem Weg, insbesondere mit Hilfe von Hochfeld-NMR-Spektren, aufgeklärt. Zusätzlich wird die Struktur 5 durch die rasche, quantitative Photoisomerisierung in das farbige Dimere S2-7 gesichert, dessen Konstitution 7 durch Vergleich mit dem Anthronanil 11 und Hydrolyse zum (2-Aminophenyl)anthron 9 bewiesen wird. Bei Raumtemperatur tritt rasche Diastereotopomerisierung der Benzolringe der 9,10-Dihydroanthracen-Systeme von S2-7 durch N-Inversion ein (1H-, 13C-NMR). Aufgrund des 1H-NMR-Spektrums bei Abwesenheit von raschem Austausch ( - 60°C) besitzt das farbige Produkt S2- und nicht C2-Symmetrie. Es wird angenommen, daß zunächst das Azahomotriptycen 2b mit einer formalen Brückenkopf-CN-Doppelbindung entsteht, das zu den rotationsisomeren 1,4-Diradikalen 13 und 14 dimerisiert, die zur Zwischenstufe 15 bzw. dem [2 + 2]-Dimeren 5 cyclisieren. Photochemische [2 + 2]-Cycloeliminierung von 5 ergibt das Dimere S2-7.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3560-3569 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Complexes of Instable Ylides, VII. Synthesis and Reactivity of as an Example of an Ylide Chelate Complex Containing an Exocyclic C =C Double BondThe sulfur ylide complex (CO)5Cr[CH2S(O)Me2] reacts with 1,1-bis(diphenylphosphino)-ethene (1) to yield the five-membered metalla-heterocycle 2 with a reactive exocyclic C =C double bond. To this double bond carbon-, hydrogen-, phosphorus-, and sulfur nucleophiles are easily added.
    Notes: Der Schwefelylidkomplex (CO)5Cr[CH2S(O)Me2] reagiert mit 1,1-Bis(diphenylphosphino)-ethen (1) zu dem fünfgliedrigen Metallacyclus 2, der eine reaktive exocyclische C =C-Doppelbindung aufweist. An diese werden Nucleophile mit C, H, P und S als Donoratomen glatt addiert.
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: An Investigation of 6-Deuterio-1,2,3,5-tetramethyl-4-methylene-endo- and -exo-6-(trideuteriomethyl)bicyclo[3.1.0]hex-2-ene on the Mechanism of the Singlet Excited Photo-Isomerization of the Homofulvene SystemSyntheses of 6-deuterio-1,2,3,5-tetramethyl-4-methylene-endo- and -exo-6-(trideuteriomethyl)bicyclo[3.1.0]hex-2-ene ([endo-6-CD3, 6-D]-1 and [exo-6-CD3, 6-D]-1) are reported. Following excitation to the S1-state both compounds isomerize to 6-deuterio-1,2,3,4-tetramethyl-5-methylene-6-(trideuteriomethyl)-1,3-cyclohexadiene ([6-CD3, 6-D]-2). The positions of the labelled atoms in 2 are discussed with respect to the mechanism of the photoisomerization 1 → 2.
    Notes: Die Synthesen von 6-Deuterio-1,2,3,5-tetramethyl-4-methylen-endo- und -exo-6-(trideuteriomethyl)bicyclo[3.1.0]hex-2-en ([endo-6-CD3, 6-D]-1 und [exo-6-CD3, 6-D]-1) werden beschrieben. Beide Verbindungen werden nach Anregung in den S1-Zustand zum 6-Deuterio-1,2,3,4-tetramethyl-5-methylen-6-(trideuteriomethyl)-1,3-cyclohexadien ([6-CD3, 6-D]-2) isomerisiert. Aus den Positionen der markierten Atome im Produkt 2 werden Folgerungen über den Mechanismus der Photo-Isomerisierung 1 → 2 abgeleitet.
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    Berichte der deutschen chemischen Gesellschaft 118 (1985) 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with Aliphatic Dialdehydes, XXXIX. The Conformation of Trinuclear [2.2.2]Heptamethinediium Cyanine Dyes with Indoline End GroupsAccording to ESR and ESCA spectroscopic measurements as well as X-ray analyses the [2.2.2]-heptamethinediium cyanine dyes 1 and 2 exist in the crystalline state and probably in solution as vinylogous amidinium ions (γ-substituted pentamethine cyanine or dicarbocyanine dyes) 1b and 2a.
    Notes: Nach ESR- und ESCA-spektroskopischen sowie röntgenographischen Befunden liegen die [2.2.2] Heptamethindiium-Cyaninfarbstoffe 1 und 2 in kristalliner Form und wahrscheinlich auch in Lösung nicht - wie bislang angenommen - als methinyloge Guanidinium-Ionen 1a und 2a vor, sondern als vinyloge Amidinium-Ionen (γ-substituierte Pentamethincyanin oder Dicarbocyaninfarbstoffe (1b und 2b.
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  • 82
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1345-1351 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Influence of Steric Effects on the Selectivity of Radical CC Bond Formation ReactionsBulky substituents R1 and R2 at radical 5 decrease the rate of addition to diethyl fumarate to a larger extent than to methyl acrylate (Table 1). The comparison with H-abstraction, which is only slightly influenced by steric effects, shows that 5e (R2 = t-C4H9) reacts at least 235 times slower with diethyl fumarate than 5a (R2 = CH3) (Table 2). Therefore, the stereoselectivity of cyclic radicals 1 (n = 1, 2) increases if the CC bond formation reaction is carried out with diethyl fumarate instead of methyl acrylate.
    Notes: Sperrige Substituenten R1 und R2 am Radikal 5 verringern die Additionsgeschwindigkeit an Fumarsäure-diethylester stärker als die Additionsgeschwindigkeit an Acrylsäure-methylester (s. Tab. 1). Der Vergleich mit dem von sterischen Effekten nur wenig beeinflußten H-Einfang zeigt, daß 5e (R2 = t-C4H9) mindestens 235mal langsamer mit Fumarsäure-diethylester reagiert als 5a (R2 = CH3) (s. Tab. 2). Deswegen steigt die Stereoselektivität der cyclischen Radikale 1 (n = 1,2) um den Faktor 5-7, wenn bei der CC-Verknüpfungsreaktion Fumarsäureester anstelle von Acrylsäureester eingesetzt wird.
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  • 83
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    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1329-1344 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: d1- and d3-Selective Reactions of Sulfur-substituted Allylic Titanium Derivatives with Aldehydes and KetonesAs previously reported, double deprotonation of allylmercaptane with butyllithium produces the moderately to poorly d3-selective dilithium derivative 1a of thioacrolein (or 1-thiabutadiene). Addition of an equimolar amount of chlortriisopropoxytitanium generates a reagent 1c, which combines with aldehydes and ketones almost exclusively in the γ-position (d3-reactivity, products 2, Table 1, 18 examples). The 2-methyl analogue 4b exhibits a similar d3-selectivity, with somewhat lower chemical yields (products 5, Table 2, 7 examples). In contrast to the dianion derivatives, methyl- and phenyl-allyllithium combine with chlorotriisopropoxytitanium to give reagents (6a, 6b) which add to the same electrophiles practically only in the α-RS-position (d1-reactivity, products 7 and 8, Table 3, 12 examples). Possible conversions of the selectively produced α- and γ-adducts to vinyloxiranes, to γ-hydroxy- and to ε-keto aldehyde derivatives are discussed (Scheme 1). Some examples of Hg(II)-assisted alcoholyses (CH3OH, C2H5OH) of γ-adducts 2 to 2-alkoxytetrahydrofurans (9, 10) are described (Scheme 2, Table 4). „Titanation“ of the Li derivatives not only causes high regioselectivity, but also excellent chemical selectivity of the nucleophilic reagents: they preferentially add to aldehydes vs. ketones and are compatible with other functional groups, such as CN, NO2, I, in the substrate.
    Notes: Das durch doppelte Deprotonierung von Allymercaptan erzeugte Dilithium-Derivat 1a des Thioacrolein- (oder 1-Thiabutadien-)Dianions wird durch Zusatz einer äquimolaren Menge Chlortriisopropoxytitan zu einem Reagenz 1c, das sich mit Aldehyden und Ketonen praktisch ausschließlich in γ-Stellung zum Schwefel vereinigt (d3-Reaktivität, Produkte 2, Tab. 1, 18 Beispiele). Dasselbe gilt für das 2-Methyl-Analoge 4b, welches - in etwas schlechterer Ausbeute - zu über 90% bevorzugt in γ-Stellung reagiert (Produkte 5, Tab. 2, 7 Beispiele). Im Gegensatz zu den Dianionderivaten (1c, 4b) reagieren die Mono-Anionderivate (6a, 6b), die man beim Versetzen von lithiierten Methyl- oder Phenyl-allylsulfid mit Chlortriisopropoxytitan erhält, mit denselben Elektrophilen praktisch vollständig selektiv in α-Stellung zur RS-Gruppe (d1-Reaktivität, Produkte 7 und 8, Tab. 3, 12 Beispiele). Die Umwandlung der selektiv zugänglichen α- und γ-Addukte in Vinyloxirane, γ-Hydroxy- und ε-Ketoaldehyd-Derivate wird diskutiert (Schema 1), und es werden einige Beispiele für die durch Quecksilber(II)-chlorid assistierte Alkoholyse (CH3OH, C2H5OH) von γ-Addukten 2 zu 2-Alkoxytetrahydrofuranen (9, 10) beschrieben (Schema 2, Tab. 4). Die „Titanierung“ der Li-Derivate führt nicht nur zu hoher Regioselektivität, sondern auch zu der für Organotitanverbindungen typischen hohen chemische Selektivität (Aldehyd vs. Keton; Addition an Aldehyd- oder Ketocarbonylgruppe in Gegenwart von Cyan-, Nitro- oder Iodsubstituenten).
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  • 84
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1352-1370 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Low Coordinated Phosphorus Compounds, 30. 1-Chloro-2-phenyl-2-(trimethylsilyl)-1-phosphaethene as a Structural Part for New PhosphaalkenesNew phosphorus-substituted phosphaalkenes are synthesized via a reaction of 1-chloro-2-phenyl-2-(trimethylsilyl)-1-phosphaethene (1) with alcohols, amines, amides, phosphanes, and organometallic reagents. Their structures are well documented by NMR data and in the cases of compounds 3a, 5a and 13 also by an X-ray analysis. Properties and some reactions of the new compounds are given.
    Notes: Durch Umsetzung von 1-Chlor-2-phenyl-2-(trimethylsilyl)-1-phosphaethen (1) mit Alkoholen, Aminen, Amiden, Phosphanen und metallorganischen Reagenzien werden neue, am Phosphor substituierte Phosphaalkene erhalten. Ihre Strukturen werden durch NMR-spektroskopische Daten, im Fall der Verbindungen 3a, 5a und 13 auch durch Röntgenbeugungsanalyse belegt. Eigenschaften und einige Reaktionen der neuen Stoffe werden mitgeteilt.
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  • 85
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1371-1382 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Organic Thiocyanates, Selenocyanates, and Cyanates with Malonyl ChlorideOrganic thiocyanates and selenocyanates react with malonyl chloride to form the pyrano-oxazinediones 1a, b and 2 a, b. Compound 4 is obtained in the case of phenacyl thiocyanate. With the exception of compound 6, nucleophilic substitution of the bromine atom in compound 1 a is not possible. Excess n-propylamine leads to 7, while reaction in acidic medium gives 5. The reaction product of malonyl chloride and aromatic cyanates is strongly dependent on the reaction conditions. At temperatures up to + 20°C, β-lactams 8a - g and hydrolysis products 9 a - e, respectively, are formed. At 30 - 70°C substances 11a, d - f, at 60 - 90°C cyclization products 10a, d - g, and at temperatures of approx. 120°C decarboxylation products 12a, b, d are formed. An X-ray structural analysis is made of 9b.
    Notes: Organische Thio- und Selenocyanate reagieren mit Malonylchlorid zu den Pyrano-oxazindionen 1a, b und 2a, b; im Falle von Phenacylthiocyanat entsteht 4. Nucleophile Substitution des Bromatoms in 1a ist außer zu Verbindung 6 nicht möglich, ein Überschuß an n-Propylamin führt zu 7, während Umsetzung in saurem Medium 5 ergibt. Das Reaktionsprodukt von Malonylchlorid und aromatischen Cyanaten ist stark abhängig von den Reaktionsbedingungen - bei Temperaturen bis + 20°C entstehen die β-Lactame 8a-g bzw. die Hydrolyseprodukte 9a-e, bei 30 - 70°C die Substanzen 11a,d - f, bei 60 - 90°C die Cyclisierungsprodukte 10a, d - g und bei Temperaturen von ca. 120°C die Decarboxylierungsprodukte 12a, b, d. Von 9b wird eine Röntgenstruktur-analyse durchgeführt.
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  • 86
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Adducts of Chalcogens with Bis(di-tert-butylphosphino)sulfur Diimide - Solid State Structures of Bis[di-tert-butyl(thiophosphinyl)]- and Bis[di-tert-butyl(selenophosphinyl)]sulfur DiimideBis(di-tert-butylphosphino)sulfur diimide, S(N — PtBu2)2 (1), adds sulfur and selenium at both phosphorus atoms to give the new chalcophosphinyl-substituted sulfur diimides S[N — P(Y)tBu2]2 (Y = S (2a), Se (2b)). According to the single-crystal X-ray structure analyses, 2a and 2b are present in the unsymmetrical Z/E-configuration in the solid state. However, the 31P NMR spectra give no indication of non-equivalence of the two phosphorus substituents in solution.
    Notes: Bis(di-tert-butylphosphino)schwefeldiimid, S(N — PtBu2)2 (1), addiert Schwefel und Selen an beide Phosphoratome unter Bildung der neuen Chalkophosphinyl-substituierten Schwefeldiimide S[N — P(Y)tBu2]2 (Y = S (2a), Se (2b)). Nach den Einkristall-Röntgenstrukturanalysen liegen 2a und 2b im Festkörper in der unsymmetrischen Z/E-Konfiguration vor. Dagegen geben die 31P-NMR-Spektren keinen Hinweis auf eine Nichtäquivalenz der beiden Phosphorsubstituenten in Lösung.
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  • 87
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3673-3682 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Enantioselective Addition of Aryl Groups to Aromatic Aldehydes Using Chiral Aryltitanium Binaphthol DerivativesChiral, non-racemic organotitanium reagents are generated in situ from binaphthol, chlorotriisopropoxytitanium and aryl Grignard reagents in tetrahydrofuran (THF). These reagents transfer aryl groups to aromatic aldehydes with high enantioselectivity [eq. (1)-(3)]. By this method, enantiomerically pure benzhydrols are available (3 - 13, Table 1). In the cases, in which the absolute configuration of the products is known, the reaction occurs with relative topicity lk.
    Notes: Die aus chiralem, nicht racemischem Binaphthol, Chlorotriisopropoxytitan und Aryl-magnesiumbromiden in Tetrahydrofuran (THF) in situ erzeugten Organotitanreagentien übertragen die Arylgruppe mit hoher Enantioselektivität auf aromatische Aldehyde [Gleichungen (1)-(3)]. So sind praktisch enantiomerenreine Benzhydrole zugänglich (3 - 13, Tab. 1). Die Reaktion verläuft in den Fällen, in welchen die absolute Konfiguration der Benzhydrole bekannt ist, mit relativer Topizität lk.
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  • 88
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3664-3672 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesen, Absorptions- und Fluoreszenzspektren von 7-Hydroxy-3-pyridylcumarinen, deren Ethern, Estern und quartärisierten DerivatenEs wurden 7-Hydroxycumarine 4 mit einem 2-, 3- oder 4-Pyridylsubstituenten in 3-Stellung sowie deren Ether (3), Ester (5, 6) und quartärisierten Derivate (7 - 9) mit Hilfe einer generell anwendbaren Methode hergestellt, welche von 2-Hydroxy-4-methoxybenzaldehyd (1) ausgeht. Die Absorptions- und Fluoreszenzspektren in Methanol sowie Wasser von verschiedenem pH-Wert werden angegeben und die Effekte der Substituenten auf Spektren und pKa-Werte diskutiert.
    Notes: 7-Hydroxycoumarins 4 with a 2-, 3- or 4-pyridyl substituent in position 3, their ethers (3), esters (5, 6), and quaternized derivatives (7 - 9) have been synthesized by a generally applicable method starting from 2-hydroxy-4-methoxybenzaldehyde (1). The absorption and fluorescence spectra in methanol and water of different pH values are reported, and the effects of substituents on spectra and pKa values are discussed.
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  • 89
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3700-3713 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbenes, 30. Metal-catalyzed Decomposition of 4-Diazomethyl-4H-pyrans - a New Access to the Oxepin SystemElectrophilic diazoalkane substitution at the lithiated diazomethyl compounds 5a - d with the pyrylium salt 6 yields the 4-diazomethyl-4H-pyrans 7a - d. Only in the case of 5d competitive attack in the 2-position of the pyrylium salt is observed, leading ultimately to the formation of the pyrazole 9. μ-Allylpalladium chloride-catalyzed decomposition of 7a - d in benzene gives in nearly quantitative yields the oxepins 12a - d. They react with the triazoledione 14 under [4 + 2]-cycloaddition followed by a hetero Cope rearrangement producing the triazolopyridazines 17a - d. An X-ray analysis of 17b has been performed.
    Notes: Elektrophile Diazoalkansubstitution an den lithiierten Diazomethylverbindungen 5a - d mit dem Pyryliumsalz 6 liefert die 4-Diazomethyl-4H-pyrane 7a - d. Nur im Falle von 5d beobachtet man auch den Angriff in der 2-Position des Pyryliumsalzes; dies führt in letzter Konsequenz zur Bildung des Pyrazols 9. μ-Allylpalladiumchlorid-katalysierte Zersetzung von 7a - d in Benzol liefert in fast quantitativen Ausbeuten die Oxepine 12a - d. Diese reagieren mit dem Triazoldion 14 unter [4 + 2]-Cycloaddition bei nachfolgender Hetero-Cope-Umlagerung zu den Triazolopyridazinen 17a - d. Von 17b wurde eine Röntgenstrukturanalyse angefertigt.
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  • 90
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Kinetic and Mechanistic Investigations of Transition Metal Complex Reactions, XVIII. Insertion of Diorganylcyanamides into the Metal-Carbene Bond - Preparative and Kinetic InvestigationsArylcarbene(pentacarbonyl) complexes, (CO)5M[C(Ph)R1] (M = Cr, Mo, W; R1 = Ph, OMe), react with diorganylcyanamides, R2R3N—C ≡ N (R2, R3 = Me, Et, Pr, iPr, Ph), via insertion of the C≡N group into the metal-carbene bond to give {[(arylmethylene)amino]-(diorganylamino)carbene}pentacarbonyl complexes, (CO)5M[C(NR2R3)N=C(Ph)R1]. The reaction follows a second-order rate law, first order each in the concentrations of the complex and the cyanamide. The rate constant increases slightly with increasing ability of the amino substituents R2 and R3 to donate electron density. The activation enthalpies are small (ΔH≠ = 37.5 to 40.6 kJ · mol-1), the activation entropies are strongly negative (ΔS≠ = -123 to -133 J · mol-1 · K-1). The reaction is initiated by nucleophilic attack of the cyanamide via the nitrile nitrogen at the carbene carbon.
    Notes: Arylcarben(pentacarbonyl)-Komplexe, (CO)5M[C(Ph)R1] (M = Cr, Mo, W; R1 = Ph, OMe), reagieren mit Diorganylcyanamiden, R2R3N—C ≡ N (R2, R3 = Me, Et, Pr, iPr, Ph), unter Einschiebung der C≡ N-Funktion in die Metall-Carbenkohlenstoff-Bindung zu den {[(Arylmethylen)amino](diorganylamino)carben}pentacarbonyl-Komplexen (CO)5M-[C(NR2R3)N=C(Ph)R1]. Die Reaktion erfolgt nach einem Geschwindigkeitsgesetz zweiter Ordnung, jeweils von erster Ordnung bezüglich der Komplex- und der Cyanamid-Konzentration. Die Geschwindigkeitskonstante nimmt mit steigender Donatorstärke der Amino-substituenten R2 und R3 geringfügig zu. Die Aktivierungsenthalpien sind niedrig (ΔH≠ = 37.5 bis 40.6 kJ · mol-1), die Aktivierungsentropien stark negativ (ΔS≠ = -123 bis -133 J · mol-1 · K-1). Die Reaktion wird durch einen nucleophilen Angriff des Cyanamids über den Nitril-Stickstoff am Carbenkohlenstoffatom eingeleitet.
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  • 91
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3714-3723 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocyclopolyaromatics, XV. On the Bromination, Acetylation, and Nitration of (all-αS)CyclotetrathiopheneBromination, acetylation, and nitration of (all-αS)cyclotetrathiophene (1) yielded in experiments with different substrate reagent ratios the substitution products of well defined structures: 2-bromo- (2; 29%) and 2,7,12,17-tetrabromo derivative (3; 82%), 2-acetyl- (4; 45%) and 2,7,12-triacetyl derivative (4; 45%) and 2,7,12-triacetyl derivative (5; 4%), 2-nitro- (9; 4%) and 2,7,12-trinitro derivative (10; 8%). In the acetylation and nitration reactions, two crystalline disubstitution products were formed additionally in each case. The position of the second substituent in these products is not clear today.
    Notes: Die mit verschiedenen Substrat-Reagenz-Verhältnissen durchgeführte Bromierung, Acetylierung und Nitrierung von (all-αS)Cyclotetrathiophen (1) lieferte die Substitutionsprodukte gesicherter Konstitution: 2-Brom- (2; 29%) und 2,7,12,17-Tetrabrom-Derivat (3; 82%), 2-Acetyl- (4; 45%) und 2,7,12-Triacetyl-Derivat (5; 4%) sowie 2-Nitro- (9; 4%) und 2,7,12-Trinitro-Derivat (10; 8%). Bei der Acetylierung und Nitrierung entstanden jeweils zusätzlich zwei kristalline Disubstitutionsprodukte, in denen die Stellung des zweiten Substituenten noch unklar ist.
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  • 92
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3724-3736 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multi Electron Ligands, XII. Transition Metal Ligands by Reaction of Spiro[2.4]hepta-4,6-diene and Spiro[4.4]nona-1,3-diene with Lithium ArsenidesConvenient one-pot syntheses of six multi electron ligands (5, 7, 11, 13, 16b, 18b) for transition metals are described, basing on fast ring opening reactions. Besides the spiro compounds, mentioned in the title, 1,2-diphenyl-1,2-diarsolane served as educt for the ring opening reactions. Some of the ligands were reacted with FeCl2 to give ferrocenophanes (21 a, b, 22) or a ferrocene (19), respectively.
    Notes: Es werden bequeme Eintopfsynthesen von sechs Vielelektronenliganden (5, 7, 11, 13, 16b, 18b) für Übergangsmetalle beschrieben, die durch rasch ablaufende Ringöffnungsreaktionen ermöglicht werden. Außer den im Titel genannten Spiroverbindungen diente 1,2-Diphenyl-1,2-diarsolan als ringöffnendes Edukt. Einige der Liganden wurden mit FeCl2 zu Ferrocenophanen (21 a, b, 22) bzw. einem Ferrocen (19) komplexiert.
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  • 93
    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, 159. [2 + 2] Cycloadditions of (tert-Butylimino)(2,2,6,6-tetramethylpiperidino)borane with Carbon Dichalcogenides[2 + 2] Cycloadditions of CO2, COS, CS2, and CSe2 and the aminoiminoborane 1 give access to the azaboretidines 2-5. These decompose thermally or photolytically with formation of (CH3)3C—N =C =E′ (E′ = O, S, Se) and the dimers of the (tetramethylpiperidino)boron chalcogenides 7-9. The X-ray structure analyses of the sulfur containing heterocycles 4 and 8 reveal the presence of planar four-membered rings. The C2N-unit of the tetramethylpiperidino group in 4 approaches a perpendicular arrangement with four-membered ring (interplanar angle 72°), in 8 however, the two planes are twisted to each other by 17° only.
    Notes: CO2, COS, CS2 und CSe2 reagieren mit dem Aminoiminoboran 1 unter [2 + 2]-Cycloaddition zu den Azaboretidinen 2-5. Diese zerfallen thermisch oder photolytisch unter Abspaltung von (CH3)3C—N =C =E′ (E′ = O, S, Se) und Bildung der dimeren (Tetramethyl-piperidino)borchalkogenide 7-9. Die Röntgenstrukturanalyse der schwefelhaltigen Heterocyclen 4 und 8 zeigt planare Vierringe auf. In 4 bildet das C2N-Strukturelement der Tetramethylpiperidino-Gruppe mit der Vierring-Ebene einen Winkel von 72°, in 8 sind die beiden Ebenen dagegen nur um 17° verdrillt.
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  • 94
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multi Electron Ligands, XIII. Synthesis of Transition Metal Ligands with Terminal Indene Residues Starting from Spiro[cyclopropane-1,1′-indene]Spiro[cyclopropane-1,1′-indene] is well accessible in ca. 60% yield by reaction of indene with sodium amide and 1,2-dibromoethane. The suitability of 3 as building block for the synthesis of multi electron ligands is demonstrated by one-pot preparations of 12 ligands (4b, 4c, 5, 6, 7, 9a/b, 10, 11b, 12, 13a, 13b, 14) which can offer to a transition metal atom 7, 9, or 12 electrons, respectively, if the indenyl group acts as 5e-donor.
    Notes: Spiro[cyclopropan-1,1′-inden] (3) ist durch Umsetzung von Inden mit Natriumamid und 1,2-Dibromethan in ca. 60proz. Ausbeute bequem zugänglich. Die gute Eignung von 3 als Baustein für die Synthese von Vielelektronenliganden für Übergangsmetalle wird durch Eintopfsynthesen von 12 Liganden (4b, 4c, 5, 6, 7, 9a/b, 10, 11b, 12, 13a, 13b, 14) demonstriert, die einem Übergangsmetallatom 7, 9 oder 12 Elektronen zur Verfügung stellen können, wenn die Indenylgruppe als 5e-Donor fungiert.
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  • 95
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    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3759-3770 
    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, 161. Reactions of Protic Reagents with (tert-Butylimino)(2,2,6,6-tetramethylpiperidino)boraneThe aminoiminoborane 2 adds protic reagents of type HX (X = OH, OR, OCOR, SH, SR, NH2, NHR, NHNR2) across the formal BN triple bond regiospecifically forming (tert-butylamino)(2,2,6,6-tetramethylpiperidino)boranes (3-7, 12, 13, 15, 16a,b, 17-27) which are inert towards ligand redistribution. The relative rates of addition are primarily governed by steric factors (NH3 〉 NH2R 〉 HNR2; HOR 〉 HSR 〉 HNR2). Bulky amines HNR2 will not add to 2. Excess HX (X = OH, OR, OC(O)R) reacts with the boranes formed on 1:1 addition by breaking BN bonds; however, no prediction can be made concerning which BN bond in tmp[(CH3)3CNH]BX will be cleaved.
    Notes: Das Aminoiminoboran 2 addiert protonenaktive Verbindungen HX (X = OH, OR, OCOR, SH, SR, NH2, NHR, NHNR2) regiospezifisch an die formale BN-Dreifachbindung. Dabei entstehen gegen Substituentenaustausch inerte (tert-Butylamino)(2,2,6,6-tetramethylpiperidino)borane (3 - 7, 12, 13, 15, 16a,b, 17 - 27). Die Anlagerungsgeschwindigkeit hängt qualitativ von sterischen Faktoren ab (NH3 〉 NH2R 〉 HNR2; HOR 〉 HSR 〉 HNR2). Bei sterischer Überfrachtung unterbleibt die Anlagerung an 2. Bei HX-Überschuß (X = OH, OR, OC(O)R) reagieren die durch 1:1-Addition entstandenen Borane unter Spaltung von BN-Bindungen, jedoch ist nicht vorhersehbar, welche der beiden BN-Bindungen in tmp[(CH3)3CNH]BX dabei gelöst wird.
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3805-3816 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azulenes by Vacuum Pyrolysis of Halotricyclo[7.1.0.04,6]decadienesDouble addition of halocarbenes or -carbenoids to cyclooctatetraene yields the title compounds 2. Pyrolysis of these (700°C, 0.01 mbar) gives azulenes of varying substitution patterns (4, 5, 6, and/or 7) which carry one substituent in each ring. Structure assignments follow from 1H NMR spectroscopy, sometimes after electrophilic introduction of the trifluoroacetyl residue. Nucleophilic substitutions of azulenes with two halogen atoms (giving compounds 8 or 9) occur only in the 7-membered ring; only 4b and CuCN yield some 11 in addition to 10.
    Notes: Doppelte Addition von Halogencarbenen bzw. -carbenoiden an Cyclooctatetraen liefert die Titelverbindungen 2. Deren Pyrolyse bei etwa 700°C und 0.01 mbar führt zu Azulenen mit unterschiedlichen Substitutionsmustern (4, 5, 6 und/oder 7), die in jedem Ring jeweils einen Substituenten tragen. Strukturzuordnungen ergeben sich auf Grund der 1H-NMR-Spektren, z.T. nach elektrophiler Substitution in 1- oder 3-Stellung mit dem Trifluoracetylrest. Nucleophile Substitutionen der Azulene mit zwei Halogenatomen zu den Verbindungen 8 oder 9 erfolgen ausschließlich im 7-Ring; allein 4b und CuCN geben neben 10 wenig 11.
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  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1825-1835 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of (η6-arene)2Cr2(CO)3 Complexes Containing a Formal Cr ≡ Cr Triple Bond Starting from η6-areneCr(CO)2NCCH3The photochemical reaction of η6-ArCr(CO)3 (Ar = benzene, toluene, m-xylene, mesitylene, methyl benzoate, and fluorobenzene) with acetonitrile in hexane or p-tolunitrile in THF, resp., yields complexes η6-ArCr(CO)2NCR (1 - 10). Solutions of the red acetonitrile complexes yield on warming or UV photolysis by dissoziation of the nitrile and one CO ligand in the presence of benzene the new black coordination compounds (η6-Ar)2Cr2(CO)3 (11 - 16). The spectra and an X-ray structure determination of the benzene derivative 11 verify a Cr2-unit with a formal triple bond bridged by three CO ligands. The asymmetric unit of 11 contains two halves of molecules with Cr — Cr distances of 222.6 and 221.6 pm.
    Notes: Bei der photochemischen Umsetzung von η6-ArCr(CO)3 (Ar = Benzol, Toluol, m-Xylol, Mesitylen, Benzoesäure-methylester und Fluorbenzol) mit Acetonitril in Hexan bzw. p-Tolunitril in THF entstehen Komplexe η6-ArCr(CO)2NCR (1-10). Lösungen der roten Acetonitrilkomplexe bilden in der Wärme oder bei UV-Bestrahlung unter Abspaltung des Nitril- und eines CO-Liganden in Gegenwart von Benzol die neuen schwarzen Komplexe (η6-Ar)2Cr2(CO)3 (11-16). Die Spektren und die Röntgenstrukturanalyse des Benzolderivats 11 belegen eine von drei CO-Liganden verbrückte, formal eine Dreifachbindung aufweisende Cr2-Einheit. Die asymmetrische Enheit von 11 enthält zwei Molekülhälften mit Cr — Cr-Abständen von 222.6 bzw. 221.6 pm.
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1857-1867 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Regiochemistry of the Intermolecular [8 + 2] Cycloaddition of Electron-rich Heptafulvenes: Syntheses of 1,2,3-Trisubstituted Hydroazulenes[8 + 2] Cycloadditions of 8-methoxyheptafulvene (1) with activated and electron-poor polyenophiles 2 occur regiospecifically linking C-1 (C-6) of 1 and C-1 of 2 and C-8 of 1 and C-2 of 2, respectively. Diastereomeric mixtures of hydroazulenes are formed. Assignments of the structures by 1H NMR utilize the „stereochemically fixed“ five-membered rings. It is concluded that the [8 + 2] cycloadditions are controlled by the coefficients of the atomic orbitals.
    Notes: 8-Methoxyheptafulven (1) addiert Dicyanalkene und Nitroalkene 2 regiospezifisch unter Bildung der Hydroazulene 4 - 8. Die Verknüpfung erfolgt zwischen dem exocyclischen Kohlenstoff C-8 des Heptafulvens 1 und C-2 von 2, sowie zwischen C-1 von 2 und C-1 (C-6) von 1. Die [8 + 2]-Cycloadditionen verlaufen nicht stereospezifisch. Strukturzuordungen für die Hydroazulene erfolgten durch 1H-NMR-Spektren und chemische Reaktionen. Bei der Interpretation der Stereochemie im Fünfring wurde vorausgesetzt, daß Phenylgruppen das sonst flexible Ringsystem fixieren. Eine Betrachtung mit der MO-Therapie ergibt: Die Regiochemie der [8 + 2]-Cycloaddition resultiert aus der Kontrolle durch die Atomorbital-Koeffizienten.
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  • 99
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Polyfunctional Molecules, 83. Reactions of Bis[μ-N,N-bis(diphenylphosphino)methylamine-P,P′]-μ-carbonyl-bis[chlororhodium(I)](Rh — Rh) with Alkali Metal Halides, Pseudohalides, and Sulfur DioxideRh2(μ-CO)[μ-(Ph2P)2NCH3]2Cl2 (1) reacts with alkali metal halides and pseudohalides MX (M = K, Na; X = I, N3, NCO, NCS, and CN) in methanolic suspension to give the new A-frame species Rh2(μ-CO)[μ-(Ph2P)2NCH3]2X2 (2a - e). The reaction of 1 with NaBr leads to a mixture of 1, Rh2(μ-Co)[μ-(Ph2P)2NCH3]2Br2 (2f), and Rh2(μ-CO)[μ-(Ph2P)2NCH3]2(Br)Cl (3), which have been identified by their mass spectra. It didn't succeed in reacting 1 with NaF. With SO2 1 reacts under replacement of the bridging CO group to give the A-frame complex Rh2[μ2η1-SO2(S)]-[μ-(Ph2P2)NCH3]2Cl2 (5). The new compounds have been characterized, as far as possible, by their mass, 31P, 1H NMR, IR, FIR, Raman, and ESR spectra.
    Notes: Rh2(μ-CO)[μ-(Ph2P)2NCH3]2Cl2 (I) setzt sich mit Alkalimetallhalogeniden und -pseudohalogeniden MX (M = K, Na; X = I, N3, NCO, NCS und CN) in methanolischer Suspension zu den neuen A-Frame-Komplexen Rh2(μ-CO)[μ-(Ph2P)2NCH3]2 X2 (2a - e) um. Die Reaktion von 1 mit NaBr führt nur zu einem Gemisch aus 1, Rh2(μ-CO)[μ-(Ph2P)2NCH3]Br2 (2f) und Rh2(μ-CO)[μ-(Ph2P)2NCH3]2(Br)Cl (3), die durch ihre Massenspektren identifiziert wurden. Eine Umsetzung von 1 mit NaF gelang nicht. Mit SO2 tauscht 1 das Brücken-CO aus und bildet den A-Frame-Komplex Rh2[μ2η1-SO2(S)][μ-(Ph2P)2NCH3]2Cl2 (5). Die neuen Verbindungen wurden, soweit möglich, durch Massen-, 31P-, 1H-NMR-, IR-, FIR-, Raman- und ESR-Spektren charakterisiert.
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  • 100
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and X-Ray Analysis of 1,2,3,4,4a,9,9a,10-Octahydro-syn-17-methyl-9,10[1′,2′]-benzeno-1,4-methanoanthracene, a Strained Alkylaromatic Compound. Comparison with Force-Field CalculationsThe synthesis of 2 is described and the structure is determined by single cristall X-ray analysis. Steric repulsions result in significant deviations from standard geometries, which are fairly predicted by force-field calculations (Allinger's MMPI). The largest deviations are due to an underevaluation of the repulsive interaction of phenyl with the methyl group.
    Notes: Es wird die Synthese der Titelverbindung 2 beschrieben und die Struktur durch Röntgenstruktur-analyse bestimmt. Eine sterische Hinderung äußert sich in signifikanten Abweichungen von der Normalgeometrie, die durch die Kraftfeld-Rechnungen (Allingers MMPI) tendentiell richtig vorhergesagt wird. Die größten Abweichungen beruhen auf einer Unterschätzung der abstoßenden Wechselwirkung der Phenyl- und der Methylgruppe.
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