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  • General Chemistry  (1,091)
  • Inorganic Chemistry  (773)
  • Wiley-Blackwell  (1,864)
  • 2015-2019
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  • 1991  (1,864)
  • 101
    Electronic Resource
    Electronic Resource
    2-Phosphaindolizines (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 475-480 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Azaphosphole, annulation to pyridine ; 2-Phosphaindolizines ; Pyridinium bromides, 1,2-dialkyl ; Phosphorus(III) chloride, condensation with CH2 groups ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240309
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  • 102
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    Medizinisch interessante Metallchelate, III. 99mTc-Komplexe mit vierzähnigen Dibrenzkatechin-Liganden (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 487-491 
    Details
    ISSN: 0009-2940
    Keywords: Bis[3-(2,3-dihydroxyphenoxy)propyl]amine hydrochloride ; 99mTc uptake ; Technetium, radiopharmaceutical containing ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Chelates of Medical Interest, III. - 99mTc Complexes with Tetradentate Dicatechol LigandsThe dicatechol ligand bis[3-(2,3-dihydroxyphenoxy)propyl]-amine hydrochloride, DIPACE (6), reduces the 99m[TcO4]- ion to lower valent 99mTc and subsequently forms a complex with the reduced 99mTc. The structure of benzylbis[3-(2,2-dimethyl-1,3-benzodioxol-4-yloxy)propyl]amine (4) is determined by X-ray crystallography.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240311
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  • 103
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    Preparation and Crystal Structures of 2-Aminoethyl Phosphate Complexes of Magnesium, Calcium, and Zinc (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 509-513 
    Details
    ISSN: 0009-2940
    Keywords: 2-Aminoethyl phosphate complexes ; Magnesium complexes ; Calcium complexes ; Zinc complexes ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystalline magnesium, calcium, and zinc 2-aminoethyl phosphate complexes containing the monoanions PEAH⊖ have been prepared as the tetrahydrates (Ca, Zn) and the hexahydrate (Mg), and their structures determined by single-crystal X-ray methods. The structures of monoclinic Ca(PEAH)2·4 H2O and Zn(PEAH)2·4 H2O (space group C2/c) both contain polymeric chains with metal ions connected by bridging phosphate groups. The zinc atoms are in a tetrahedral environment of four oxygen atoms, while the calcium atoms are found to be hexacoordinated with two additional oxygen atoms from water molecules in axial positions. The triclinic Mg(PEAH)2·6 H2O (space group \documentclass{article}\pagestyle{empty}\begin{document}$ P\bar 1 $\end{document}) contains discrete complex units with hexacoordinate magnesium atoms octahedrally surrounded by six oxygen atoms, four of which from water molecules in the equatorial plane and two from phosphate groups in axial positions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240315
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  • 104
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    A Versatile Synthesis of 1,4-Dienes: Use of Vinyl Ethers as Vinyl Cation EquivalentsDedicated to Professor Karl Heinz Büchel on the occasion of his 60th birthday. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2785-2790 
    Details
    ISSN: 0009-2940
    Keywords: Enol ether ; Allylsilane ; Bromo ether ; 1,4-Diene ; Alkoxyalkylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The α,β-dibromo ethers 2, in situ generated from the vinyl ethers 1 and bromine, react with the allylsilanes 3 in the presence of ZnCl2 to give the β-bromo ethers 4. Treatment of 4 with Na in diethyl ether yields 1,4-dienes 5 in 62-79% overall yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241222
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  • 105
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    Small and Medium Rings, 791) 4-Azatetracyclo[3.3.0.02,8.03,6]octanes: New Hetereocycles by Addition of Sulfonyl Azides to 7-Substituted Norbornadienes - Experimental Verification of σ Interactions in the Norbornane Skeleton (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2879-2895 
    Details
    ISSN: 0009-2940
    Keywords: Cycloadditions, dipolar ; Electron-transmission spectroscopy ; Norbornane systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of six 7-substituted norbornadienes with seven sulfonyl azides has been investigated. The products consist of either the novel azatetracyclic system 1 or the stereoisomeric bicycles 2 or of a mixture of them. The chemical behaviour of 1 has been studied. Mechanistically the results may be rationalized within the frame of the Mazzocchi-Houk model. The theoretical predictions of this model, concerning the π*and σ* energies, were confirmed experimentally by using electron-transmission spectroscopy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241232
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  • 106
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    Zur Bildung von Vinylcyclopropan- und Cyclopentenderivaten aus alkenylsubstituierten Chromcarben-Komplexen: Konkurrenz von formalen [2 + 1]- und [3 + 2]-Cycloadditionen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 957-965 
    Details
    ISSN: 0009-2940
    Keywords: Chromium complexes ; Carbene ligands ; alkenyl-substituted ; [2 + 1] Cycloaddition ; Vinylcyclopropane→cyclopentene rearrangement ; Cyclopropanes ; donor-acceptor-substituted ; Pyrrole derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formation of Vinylcyclopropane and Cyclopentene Derivatives from Alkenyl-Substituted Chromium Carbene Complexes: Competition between Formal [2 + 1] and [3 + 2] Cycloadditions.The alkenyl-substituted chromium carbene complexes 1 - 4 were synthesized following the method of Aumann which starts from the corresponding aldehydes. At 80°C the styryl-substituted complex 1 and electron-deficient olefins smoothly provide vinylcyclopropane derivatives 6,8, 10, and 12 in good yields. On the other hand, methyl acrylate and the anisyl- and furyl-substituted vinylcarbene complexes 2 and 3 give mixtures of the expected vinylcyclopropanes and of cyclopentene derivatives. The pyrrolyl-substituted complex 4 and methyl acrylate exclusively afford the cyclopentenes 24a/b which are the result of a hitherto unprecedented formal [3 + 2] cycloaddition of the vinylcarbene complex to the olefin. However, there are strong arguments suggesting the corresponding vinylcyclopropanes as intermediates. The very smooth vinylcyclopropane→cyclopentene rearrangement probably occurs via zwitterionic intermediates that are wellstabilized by donor and acceptor substituents. Hydrolysis of 24a/b to the cyclopentanone derivatives 25a/b demonstrates that this new route to five-membered carbocycles should have synthetic potential.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240441
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  • 107
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    OrganosubstituierteBicyclen undMonocyclen aus 2,5-Dihydro-1,2,5-oxasilaboratolaten (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1017-1023 
    Details
    ISSN: 0009-2940
    Keywords: Borates, triorgano-oxy, potassium salts ; N-Lewis base - diorgano(silyloxy)boranes ; Bicyclo[2.2.1]heptanes, heteroatom-containing, diastereomeric ; P-Lewis base - triorganoboranes, monocyclic, unsaturated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: OrganosubstitutedBicyclic and Monocyclic Compounds from 2,5-Dihydro-1,2,5-oxasilaboratolates1a)The potassium salts of the cyclic anions of (A: R, R′ = CH3; B: R = C2H5, R′ = CH3; C: R = C6H5, R′ = CH3 react with [(CH3)2NCH2]Br in THF to yield the bicyclic compounds 1a (X-ray crystal structure analysis), 1b/1b' (endo/exo-C2H5), and 1c/1c' (endo/exo-C6H5). D (R=CH3, R'=C6H5) reacts with [(CH)32NCH2]Br to form a 1:4 mixture of 1d together with the heterocycle (3d) with elimination of (CH3)2N-C3H7. - From A - D and CIP(C6H5)2 the six-membered heterocycles (2a-d) are obtained in yields of ca. 90%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240507
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  • 108
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    Metal Complexes with Tetrapyrrole Ligands, LVIII. Zirconium(IV) and Hafnium(IV) Bisporphyrinate Double Deckers: Synthesis, Spectra, Redox Potentials, and Structure (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1051-1058 
    Details
    ISSN: 0009-2940
    Keywords: Zirconium porphyrins ; Hafnium porphyrins ; Porphyrin double deckers ; Metal bisporphyrinates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of new zirconium and hafnium bisporphyrinate double deckers M(P)2 (M=Zr, Hf; P=OEP, TPP)2,3) is described. The complexes are characterized by UV/Vis/NIR and 1H-NMR spectroscopy and cyclic voltammetry. As compared with M=Ce, the redox potentials or the energies of the nearinfrared absorption bands of the corresponding radical cations [M(P)2]+ are lower by ≍ 0.2 V or higher by ≍ 2000 cm-1, respectively, Hence, there is a stronger π-π interaction between the porphyrin ligands as compared with the cerium analogues due to the smaller ionic radii of Zr(IV) and Hf(IV). X-ray crystallography of Zr(TPP)2 confirms the sandwich-like structure of the compound and the close proximity of the porphyrin ligands.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240511
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  • 109
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    Metal Bonding by Amino Acids: Preparation and Crystal Structures of Calcium Bis-L-pyroglutamate and Lithium L-Pyroglutamate (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1083-1087 
    Details
    ISSN: 0009-2940
    Keywords: Calcium bis-L-pyroglutamate ; Lithium L-pyroglutamate ; Pyroglutamate coordination and conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calcium bis-L-pyroglutamate and lithium L-pyroglutamate are prepared by reaction of the metal hydroxides with L-pyroglutamic acid in aqueous solution. In the solid state calcium bis-L-pyroglutamate adopts a layer structure, built up by sixteen-membered rings consisting of four L-pyroglutamate ligands bridging four calcium centers by their carboxylate groups. All three oxygen donors of the L-pyroglutamate ligands are attached to metal centers. The calcium atom lies at the center of a slightly distorted octahedron formed by four carboxylate oxygens and two amide oxygen atoms. Lithium L-pyroglutamate also features a layer structure. All three oxygen donors of the L-pyroglutamate ligand have contacts with metal atoms. The coordination sphere of the lithium atom is a slightly distorted tetrahedron consisting of three carboxylate oxygen atoms and one amide oxygen atom. The investigation of aqueous solutions of the compounds by multinuclear NMR (1H, 13C, 17O) indicates extensive electrolytic dissociation in dilute solutions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240515
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  • 110
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    Metallcarbonyl-Synthesen, XX. Einfache Methode zur Darstellung von Tc(CO)3-Komplexen: Synthese und Struktur der neuartigen Technetium(I)-Clusterverbindung Na[Tc3(CO)9(OCH3)4] mit Cuban-Struktur (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1107-1111 
    Details
    ISSN: 0009-2940
    Keywords: Technetium complexes ; Isocarbonyl ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Carbonyl Syntheses, XX. - Simple Method for the Preparation of Tc(CO)3 Complexes: Synthesis, Structures, and Reactivity of the Novel Cubane-Type Cluster Na[Tc3(CO)9(OCH3)4]Carbonyltechnetium complexes of type LTc(CO)3 are accessible along a simple route from Na[Tc3(CO)9(OCH3)4] (2) which represents a novel alkoxy complex of cubane-type geometry (single-crystal X-ray diffraction study). 2 is an isolable product of the incomplete carbonylation of sodium pertechnetate (1) conducted in methanol. Under carbon monoxide pressure, 2 yields the binary metal carbonyl Tc2(CO)10 (3), pentamethyl-cyclopentadiene gives the halfsandwich complex (η5-C5Me5)Tc(CO)3 (4), and with benzene/hydrochloric acid the ionic complex [(η6-C6H6)Tc(CO)3]Cl (5) is formed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240519
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  • 111
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    Synthese stabiler Alkantellurenyl-pseudohalogenide und -pseudochalkogenide: (Me3Si)3CTeX (X=-CN, - SCN, - SeCN, - NCO, - N3) und (Me3Si)3CTe-Y-TeC(SiMe3)3 (Y=- NCN-, - NSN-) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1131-1133 
    Details
    ISSN: 0009-2940
    Keywords: Alkanetellurenyl pseudohalides ; Alkanetellurenyl pseudochalcogenides ; Tellurenyl pseudohalides, pseudochalcogenides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Stable Alkanetellurenyl Pseudohalides and Pseudochalcogenides: (Me3Si)3CTeX (X=- CN, - SCN, - SeCN, - NCO, - N3) and (Me3Si)3CTe-Y - TeC(SiMe3)3 (Y=- NCN-, - NSN-)The first stable and isolable alkanetellurenyl pseudohalides and pseudochalcogenides, tris(trimethylsilyl)methanetellurenyl cyanide, thiocyanate, selenocyanate, isocyanate, azide (2-6) as well as bis[tris(trimethylsilyl)methyltelluro]carbodiimide and -sulfur diimide (7, 8) are obtained in high yields by the reaction of tris(trimethylsilyl)methanetellurenyl iodide (1) with the silver or potassium salts of the respective pseudohalides or pseudochalcogenides. 5-8 are also the first alkyltellurium(II) compounds with Te-N bonding. All compounds have been characterized by 1H-, 13C-, 125Te-NMR, mass, and IR spectroscopy.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240523
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  • 112
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    Beiträge zur Chemie des Phosphors, 211. Pentaisopropyltetracycloundecaphosphan, P11iPr5 - Darstellung und kernresonanzspektroskopische Strukturbestimmung (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1153-1157 
    Details
    ISSN: 0009-2940
    Keywords: Tetracyclo[6.2.1.02,6.05,10]undecaphosphane ; 3,4,7,9,11-pentaorganyl ; Undecaphospha-2,8-ethanonoradamantane ; Undecaphosphane(5) ; Phosphanes, polycyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Chemistry of Phosphorus, 211. - Pentaisopropyltetracycloundecaphosphane, P11iPr5 - Preparation and Structure Determination by Nuclear Magnetic ResonancePentaisopropyltetracycloundecaphosphane (1) has been obtained by reaction of iPrPCl2 with P4 and magnesium and subsequent thermolysis of the crude reaction product, and has been isolated in 91% purity. According to NMR-spectroscopic investigations, 1 has a constitution analogous to that of the hydrocarbon 2,8-ethanonoradamantane, thus being 3,4,7,9,11-pentaisopropyltetracyclo[6.2.1.02,6.05,10]undecaphosphane Compound 1 is formed as a mixture of two configurational isomers 1a and 1b, which differ from each other in their spatial arrangements of the isopropyl groups at P3 and P4.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240527
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  • 113
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    Reaktion von KSi mit M(CO)6 (M=Cr, Mo, W) und Cr(CO)5NMe3 - Struktur von [K(DME)2]2[Cr2(CO)10] (DME=1,2-Dimethoxyethan) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1167-1169 
    Details
    ISSN: 0009-2940
    Keywords: Anion-cation interactions ; Carbonyl metalates ; Chromium complexes ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of KSi with M(CO)6 (M=Cr, Mo, W) and Cr(CO)5NMe3 - Crystal Structure of [K(DME)2]2[Cr2(CO)10] (DME=1.2-Dimethoxyethane)M(CO)6 (M=Cr, Mo, W) and Cr(CO)5NMe3 are reduced by KSi in DME during several days with formation of the anions [M2(CO)10]2⊖. These can be obtained from a DME/toluene solution as pale yellow or orange crystals of [K(DME)2]2[M2(CO)10] [M=Cr (1), Mo (2), W (3)]. A crystal structure determination of the chromium compound shows that strong interactions between the [Cr2(CO)10]2⊖ and the K⊕ ions exist in the solid state, leading to the formation of one-dimensional polymeric chains. 2 and 3 are isomorphous to 1 (powder diffraction, Rietveld method).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240531
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  • 114
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    Substituenteneffekte auf die C—C-Bindungsstärke, 10. Resonanzstabilisierung von Alkylradikalen durch zwei geminale Cyangruppen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1191-1198 
    Details
    ISSN: 0009-2940
    Keywords: Bond cleavage ; C—C kinetics of ; Radicals, stability of ; Geminal substituents, energetic interaction of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of Substituents on the Strength of C-C Bonds, 10. - Resonance Stabilization of Alkyl Radicals by Two Geminal Cyano GroupsThe activation parameters of the homolytic cleavage of the Cq - Cq bonds of several dialkylated malonodinitriles (2-5) and of 1,1,2,2-tetracyanoethane (7) and the heat of dissociation of 6 in solution have been determined. Together with the ground state strain of the radical precursors (obtained from the heats of combustion or EFF calculations) the steric influence on the dissociation process has been determined. The resonance stabilization energy of α,α'-dicyanoalkyl radicals then calculated was (12.4 ± 0.9) kcal/mol. This result is discussed within the concept of capto-dative stabilization. The destabilizing interaction of two geminal cyano groups is apparently the same in the ground state of 2 - 7 and the radicals generated from them.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240535
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  • 115
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    Electron-Transfer in the Light-Promoted 1,6-Cyclodimerization of 1,1-Di-2-thienylethylene. A Thermal and Photochemical Study (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1203-1206 
    Details
    ISSN: 0009-2940
    Keywords: Dithienylethylene ; Cyclodimerization ; Photoinduced electron transfer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,1-Di-2-thienylethanol (1) undergoes light-induced (Δ 〉 400 nm) dehydration to afford 1,1-di-2-thienylethylene (2). Compound 2 is selectively converted into 1,6-cyclodimers under thermal or photochemical conditions. In these latter case the non-aromatic Diels-Alder adduct 3 can be characterized. An ET mechanism involving a methyldithienylcarbenium ion (9) as electron acceptor and a chain mechanism is proposed to account for the products.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240537
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  • 116
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    Heterocyclen mit einem Azaallyl-System, 4. 5H-Dibenz[c,e]azepine mit Donor-Gruppen in 7-Stellung (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2085-2090 
    Details
    ISSN: 0009-2940
    Keywords: 5H-Dibenz[c,e]azepines ; Imidates ; alkyl ; heterocyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterocycles with an Azaallyl System, 4.  -  5H-Dibenz[c,e]azepines with Donor Groups at the 7-Position5H-Dibenz[c,e]azepines substituted with a methoxy (1) or methylthio group (10) at the 7-position have been synthesized from 6,7-dihydro-5H-dibenz[c,e]azepin-5-one (5) by regioselective O- or S-alkylation with methyl trifluoromethansulfonate and subsequent NH-deprotonation. According to the spectroscopic properties the semicyclic 7-membered alkyl imidates exist exclusively in the benzenoid 5H structure.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240934
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  • 117
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    Stereoselective Synthesis of Alcohols, XXXVIII Stereoselective Total Synthesis of the Denticulatins (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2127-2139 
    Details
    ISSN: 0009-2940
    Keywords: Marine natural products ; Hemiketal formation, selective ; Denticulatins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total synthesis of the denticulatins 1 is described. Key feature is the efficient generation of the C-1-to-C-9 building block 37 by three consecutive stereoselective carbon - carbon bond-forming steps using chiral allylboronates. The C-10-to-C-17 building block was obtained by kinetic Sharpless resolution of an allylic alcohol followed by an Ireland-Claisen rearrangement.
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    URL: http://dx.doi.org/10.1002/cber.19911240940
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  • 118
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241001
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  • 119
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    Simple Entry into Tricyclo[3.3.0.03,7]octanes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2147-2147 
    Details
    ISSN: 0009-2940
    Keywords: Tricyclo[3.3.0.03,7]octanes ; Samarium iodide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,5-Dimethylbicyclo[3.3.0]octan-3,7-dione (2) was converted into 1,5-dihydroxy-3,7-dimethyltricyclo[3.3.0.03,7]octane (3) in the presence of Sml2 in 76% yield.
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    Thiolatokomplexe des einwertigen Golds. Synthese und Struktur von [(2,4,6-iPr3C6H2S)Au]6 und (NH4)[(2,4,6-iPr3C6H2S)2Au] (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2161-2164 
    Details
    ISSN: 0009-2940
    Keywords: Gold(I) 2,4,6-tri(isopropyl)thiophenolate, hexamer ; Aurate(I), bis[2,4,6-tri(isopropyl)thiophenolato] ammonium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiolato Complexes of Monovalent Gold. Synthesis and Structure of [(2,4,6-iPr3C6H2S)Au]6 and (NH4)[(2,4,6-iPr3C6H2S)2Au]Reaction of Au(CO)Cl with 2,4,6-tri(isopropyl)thiophenol affords hexameric gold(I) thiolate [(2,4,6-iPr3C6H2S)Au]6 (1). According to an X-ray analysis 1 forms a centrosymmetrical twelve-membered Au - S ring in the chair conformation with the linearly coordinated Au atoms at the mid-edges and the S atoms at the corners of the heterocycle. When the reaction of 2,4,6-tri(isopropyl)thiophenol is carried out with AuI in liquid ammonia the thiolato complex [(2,4,6-iPr3C6H2S)2Au]- -NH+4 (2) is obtained. It crystallizes as NH4 · 2 · 3 NH3. The gold atom in 2 is linearly coordinated by two thiolato S atoms. The ammonium cation forms hydrogen bonds with three NH3 solvate molecules.
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    Metallacyclobutene aus η2-Cyclopropen-Komplexen des Titanocens und Zirkonocens (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2165-2170 
    Details
    ISSN: 0009-2940
    Keywords: Titanocene complexes ; Zirconocene complexes ; Cyclopropene complexes ; Metallacyclobutenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metallacyclobutenes via η2-Cyclopropene Complexes of Titanocene and Zirconocene(η2-Cyclopropene)(trimethylposphane) complexes of titanocene (4, 5) and zirconocene (8) are obtained in good yields by the reaction of 1,2-diphenylcyclopropene (2) or 4,8-dioxaspiro[2.5]oct-1-ene (3) with bis(trimethylphosphane)titanocene (1) and (1-butene)(trimethylphosphane)zirconocene (7), respectively. In solution the new complexes 4 and 8 rearrange smoothly above room temperature to give the metallacyclobutene derivatives 6 and 9. All new compounds were characterized by spectroscopic methods (31P, 1H, 13C NMR), and the crystal structure of 9 was determined by an X-ray analysis.
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    Mono-, Bis- and Tris(cyclopentadienyl) Compounds - Syntheses of New Polydentate Ligands and their Molybdenum and Tungsten Complexes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2185-2190 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienes, mono-, bis-, tris- ; DNMR ; Molybdenum, η5-complexes ; Tungsten, η5-complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation reactions of cyclopentadienyl-substituted chlorosilanes CpSiMe2Cl (Cp = C5H5, C5HMe4) with a number of phenols [C6H5OH, 1,3-C6H4(OH)2, 1,4-C6H4(OH)2, 1,3,5-C6H3(OH)3] in the presence of excess base led to six novel molecules containing up to three cyclopentadienyl groups {e.g. 1,3,5-C6H3[OSiMe2(C5Me4H)]3). The dynamic behavior of 1,4-C6H4[OSiMe2(C5H5)]2 (2) was investigated by temperature-variable 1H NMR and the reaction rate of the degenerate 1,2-silicon shift determined. C6H5OSiMe2(C5H5) (1) and (2) were treated with NaH, (MeCN)3M(CO)3 (M = Mo, W), and Mel to give the η5-complexes C6H6OSiMe2 - (C5H4)M(CO)3Me (8: M = Mo, 9: M = W) and 1,4-C6H4[OSiMe2-(C5H4)M(CO)3Me]2 (10: M = Mo, 11: M = W) in good yields. The X-ray crystal structure of 11 was determined.
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    Synthesis and Molecular Structure of the Solvent-Free [LiN(SiMe3)(2,6iPr2C6H3)]2 Dimer (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2223-2225 
    Details
    ISSN: 0009-2940
    Keywords: Lithium, two-coordinate ; Lithium-nitrogen heterocycle ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [LiN(SiMe3)Ar]2 (1, Ar = 2,6-iPr2C6H3) is prepared by the reaction of HN(SiMe3)Ar with nBuLi in n-hexane. This compound with an unusual structure contains a four-membered [LiN]2 heterocycle with two solvent-free two-coordinate Li centers. Its molecular structure represents the first solid-state X-ray analysis of an uncomplexed [LiN]2 dimer.
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    URL: http://dx.doi.org/10.1002/cber.19911241013
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    Functionalized Oxovanadium Alkoxides  -  Potential Haptens (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2249-2254 
    Details
    ISSN: 0009-2940
    Keywords: Vanadium alkoxides ; Haptens ; NMR, 51V ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several new oxovanadium alkoxides and alkoxides/chlorides of the composition VOCl3-n(OR)n (n = 1, R = CPh3; n = 2 and 3, R = CPh3, iBu, cyclopentyl, tert-pentyl, octyl; n = 3, R = dodecyl, 3-methylbutyl) and the mixed ester VO(OiBu)- (OCPh3)2 have been prepared. The compounds VO(OiBu)2OR' have been synthesized, where R' is a functionalized long-chain alkyl group [  -  (CH2)8OH,  -  (CH2)6NH(FMOC),  -  (CH2)6NH2,  -  C(O)(CH2)5C(O)OMe, p-C6H4CN, p-C6H4NH2]. The chloride/carboxylate VOCl2{O2C(CH2)5CO2H} has also been obtained. The compounds are characterized, inter alia, by 51V-NMR spectroscopy. Typical 51V shift ranges are observed for specific ligand functionalities (chloride, alkoxide, carboxylate). δ(51V) values also depend on the steric requirement of the groups R and the coordination number. The importance of the functionalized esters as potential triggers for the production of abzymes with phosphatase activity is discussed.
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    URL: http://dx.doi.org/10.1002/cber.19911241017
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    Synthese und flüssigkristalline Eigenschaften von Multiethern des myo- und scyllo-Inosits (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2265-2277 
    Details
    ISSN: 0009-2940
    Keywords: Inositol ethers ; Mesogens ; Liquid crystals, thermotropic ; Hydrogen bonding ; Supramolecular structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Liquid-Crystalline Properties of myo- and scyllo-Inositol Multi EthersSelectively alkylated myo- and scyllo-inositol ethers were obtained by multi-step syntheses starting from commercially available myo-inositol. Necessary conversions of axial hydroxy groups into equatorial ones were achieved using either potassium superoxide (KO2) or potassium nitrite (KNO2) as oxygen nucleophiles for the transformation of myo- into scyllo- inositol derivatives. Polarizing microscopic and thermoanalytical studies of numerous members of three families (6, 13, and 20) of inositol ethers reveal for most of them thermotropic liquid-crystalline behavior. Furthermore, in case of the two long-chain scyllitol tetraethers 13d and e an unusual thermopolymorphism has been found. The number, position, and stereochemical arrangement of alkyl chains attached to the inositol cores strongly influence the mesogenic properties of these biomolecule derivatives, chemically vicinal diols and tetrols. The self-assembly of the studied inositol multi ethers to columnar mesophases of “supramolecular structures” is discussed considering geometrical features of these molecules and their capabilities to aggregate by hydrogen bonding.
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    URL: http://dx.doi.org/10.1002/cber.19911241020
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240101
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    Addition von Alkenen an 5-(Trifluormethyl)-1,3,2,4,6-dithiatriazin (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 39-45 
    Details
    ISSN: 0009-2940
    Keywords: 1,3,2,4,6-Dithiatriazines ; CNS Polycycles, structure determination ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of Alkenes to 5-(Trifluoromethyl)-1,3,2,4,6-dithiatriazinesDechlorination of 1,3-dichloro-5-(trifluoromethyl)-1,3,2,4,6-dithiatriazine (1) with Ph3Sb gives (CF3CN3S2)n (2) in quantitative yield. By 1,3-addition of alkenes (dicyclopentadiene, cyclopentene, cis- and trans-2-butene, propene, and ethene) to 2 the corresponding penta- (4a), tri-(5a), and bicyclic ring systems 6a, 6b, 7, 8a, 8b, and 9 are prepared in 65-85% yields. The molecular structures of 6a and 7 were determined by single-crystal X-ray analysis; the other structures were derived from NMR data. The NMR analyses are in accordance with MNDO calculations. For 4a and 5a only the thermodynamically favoured anti-isomers are found, as expected from these calculations; for 6 and 8 they show satisfactory agreement for anti/syn-proportions as determined by NMR spectroscopy. The product distribution corresponds to a symmetry-allowed alkene addition to a singlet dithiatriazine.
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    Synthese und Eigenschaften von 1,2,4,3-Thiadiazaboretidinen. Kristallstruktur des 2,4-Di-tert-butyl-3-phenyl-1,2,4,3-thiadiazaboretidins (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 47-50 
    Details
    ISSN: 0009-2940
    Keywords: Sulfur diimides ; 1,3-Cycloaddition, reductive ; 1,2,4,3-Thiadiazaboretidines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of 1,2,4,3-Thiadiazaboretidines. Crystal Structure of 2,4-Di-tert-butyl-3-phenyl-1,2,4,3-thiadiazaboretidineReaction of sulfur diimides with alkyl(aryl)bis(methylthio)boranes leads to reductive 1,3-cycloaddition of the NSN sequence with formation of the 1,2,4,3-thiadiazaboretidines 2a-g. NMR (1H, 11B, 13C, 15N, 29Si), mass spectra and the results of the X-ray analysis of 21 are reported and discussed. The 11B chemical shifts have been calculated for 3-phenyl-1,2,4,3-thiadiazaboretidine and some related model compounds by the IGLO method and correlate acceptably with the experimental values.
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    Metallatome in der Synthese von Metallclustern, II1) Reaktionen von substituierten Cyclopentadienen und Nickelocen mit Nickel- und Eisenatomen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 301-308 
    Details
    ISSN: 0009-2940
    Keywords: Metal atom synthesis ; Clusters ; Electrochemistry ; Cyclic voltammetry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Atoms in the Synthesis of Metal Clusters, II1). - Reactions of Substituted Cyclopentadienes and Nickelocene with Nickel and Iron AtomsBy vaporizing nickel atoms into solutions of tert-butyl-substituted cyclopentadienes in methylcyclohexane mononuclear sandwich compounds (1, 4, and 6 as main products) as well as tri- and tetranuclear clusters are prepared. With mono- and di-tert-butyl-substituted cyclopentadienes as ligands the new clusters 2 and 5 are obtained. In the reaction with 1,2,4-tri-tert-butylcyclopentadiene 6 is the only observed product. Hindered rotation around the metal-ligand bond vector is observed for 4 even at room temperature. When treating 1 with nickel atoms cluster 2 is formed, indicating some importance of 1 during the formation of 2 in the above reaction. Clusters 2 and 5 contain hydrido ligands, which could be identified in the case of tris(1,3-di-tert-butyl-η5-cyclopentadienyl)trinickel dihydride (5) by a single crystal structure determination as μ3-H bridges. A tetrahedral structure is found for the cluster 2 by X-ray crystallography. With the aid of MS, IR, magnetic measurements, and cyclovoltammetric investigations 2 is identified as a mixture of 2a and 2b bearing one or three bridging hydrogens, respectively. In general 2a, 2b, and 5 show a rich redox chemistry with reversible redox couples between -2 and +2. Reaction of iron atoms, nickelocene, and mesitylene in methylcyclohexane at -120°C leads unexpectedly to cluster 3, tetrakis(η5-cyclopentadienyl)tetranickel trihydride and a not yet identified (η5-cyclopentadienyl)mesityleneiron complex. Possible formation routes for 1-6 are discussed.
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    1,8-Bis(diphenylphosphino)anthracene and Metal Complexes1) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 333-336 
    Details
    ISSN: 0009-2940
    Keywords: Phosphine ligand ; Anthracene ; Nickel(II) complexes ; Palladium(II) complexes ; Cyclometallated chelate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 4 was synthesized from dipotassium 1,8-anthracenedisulfonate (9) and potassium diphenylphosphide (Ph2PK). On reaction of 4 with nickel(II) chloride and bis-(benzonitrile)palladium(II) chloride, cyclometallation of the C - H bond in anthracene 9-position led to the square-planar chelate complexes 11 and 13, respectively. In the case of the palladium complex 13, the cyclometallated structure was proved by X-ray structure analysis. Treatment with aqueous potassium cyanide did not remove nickel from 11, but converted 11 into 12 by substitution of chloride with cyanide, demonstrating the high stability of these cyclometallated chelate complexes.
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    Untersuchungen zum Reaktionsverhalten von Benzocyclopropen unter Yb(fod)3-Katalyse (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 353-356 
    Details
    ISSN: 0009-2940
    Keywords: Benzocyclopropene ; 1,3-Dihydroisobenzofurans ; Yb(fod)3 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experiments Concerning the Reactions of Benzocyclopropene under Yb(fod)3 Catalysis1,3-Dihydroisobenzofuran derivatives 3a - e and 5a - c are obtained by reactions of α,β-unsaturated carbonyl compounds with benzocyclopropene (1). The yields increase by addition of Yb(fod)3. Aromatic aldehydes react in the same way. Yb(fod)3 has no influence on the reactions of α,β-unsaturated hydrazones with 1.
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    URL: http://dx.doi.org/10.1002/cber.19911240217
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    Synthese heterocyclischer Dialkine und deren Umsetzung mit CpCo(CO)2 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 357-363 
    Details
    ISSN: 0009-2940
    Keywords: Heterodiynes, medium-sized ; [2.2](2,5)-Thiophenophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Heterocyclic Diynes and their Reaction with CpCo(CO)2The preparation of the heterocyclic diynes 1,6-dithia-3,8-cyclodecadiyne (1b), thia-3,8-cyclodecadiyne (11), 1-thia-6-selana-3,8-cyclodecadiyne (12), oxa-3,8-cyclodecadiyne (13), 1,6-dioxa-3,8-cyclodecadiyne (14), 1-oxa-6-thia-3,8-cyclodecadiyne (15), 1,6-diselena-3,8-cyclodecadiyne (26), thia-3,9-cyclounde-cadiyne (22a), thia-3,13-cyclopentadecadiyne (22b) and its selena analogues 23a, 23b is described. The thia and monoselena compounds are obtained by a thia- or selenacyclization of the corresponding dibromides. Compound 26 has been obtained by a Misumi coupling reaction. The thiacycloalkadiynes of medium-sized rings (10, 11) react with CpCo(CO)2 to yield [2,2](2,5)thiophenophane derivatives. Acyclic thiadialkynes or thiacycloalkadiynes of larger ring size (22b) with CpCo(CO)2 by [2 + 2 + 2] cycloaddition.
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    URL: http://dx.doi.org/10.1002/cber.19911240218
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    A New Route to Alkoxy Radicals  -  Photochemical Reactions with (Alkylperoxy)cobaloximes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 387-390 
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    ISSN: 0009-2940
    Keywords: Peroxy compounds ; Cobaloximes ; Oxygen insertion ; Radicals, alkoxy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkoxy radicals have been generated by photochemical reactions of (alkylperoxy)cobaloximes 1. The occurrence of alkoxy radicals has been proved by characteristic cyclization and β-scission reactions of the reactive intermediates.
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    URL: http://dx.doi.org/10.1002/cber.19911240223
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    On the Electronic Structure of Phosphabutatriene and Related Phosphacumulenes. A Theoretical Study (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 271-274 
    Details
    ISSN: 0009-2940
    Keywords: Phosphacumulenes ; Cumulenes ; Calculations, MNDO, SCF ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound phosphabutatriene possesses two energetically closely spaced frontier orbitals, as in methylenephosphane and in phosphaallene. They are built up from the π system or the s̰ orbital of phosphorus by interaction with neighboring π bonds. The extension of these frontier orbitals over all (heavy) atoms makes self-dimerization to different cyclobutane derivatives feasible. Substituent effects on the ordering of s̰ and π are analyzed. Vibrational analyses indicate P=C vibrations of low intensity which decrease with increasing length of the heterocumulene chain. The analysis is extended to the two next higher homologs, which are hitherto experimentally unknown.
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    Dioxirane Epoxidation of α,β-Unsaturated Ketones (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 227-232 
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    ISSN: 0009-2940
    Keywords: Epoxidation ; Dioxiranes ; Ketones, α,β-unsaturated ; (E)-Chalcones ; (E)-2′-Hydroxychalcones ; 2-Cycloen-1-ones ; Caroate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of epoxides 3a - r is achieved in excellent yields by reaction of the α,β-unsaturated ketones 1a-c, 4,4′-disubstituted (E)-chalcones 1d-o, and 2′-hydroxy-4-substituted (E)-chalcones 1p - r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl)dioxirane (2b). This method constitutes a useful alternative to the Weitz-Scheffer epoxidation (alkaline H2O2) of such electronpoor substrates.
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    Umlagerungen von 5,5,6,6-Tetraalkyl-2-norbornyl-Kationen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 241-245 
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    ISSN: 0009-2940
    Keywords: 2-Norbornyl cations, 5,5,6,6-tetramethyl- ; Tetracyclo[4.2.2.12,5.01,6]undec-3-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 5,5,6,6-Tetraalkyl-2-norbornyl CationsWhen the 6,6-dimethyl-2-norbornyl cation (9) is generated from the tosylhydrazone 5 by way of the diazonium ion 8, a 2H label is distributed equally between positions 1 and 2 of the exo-alcohol 10. The degeneracy of 9, previously derived from solvolytic studies, is thus confirmed for the deaminative route. 5,5,6,6-Tetramethyl-2-norbornanone (25) and tetracyclo[4.2.2.12,5.01,6]undecan-3-one (31) are prepared by using Diels-Alder methodology. The corresponding tosylhydrazones 26 and 32 are employed as precursors for the 5,5,6,6-tetramethyl-2-norbornyl and tetracyclo[4.2.2.12,5.01,6]undec-3-yl cations (11 and 12). Again, the distributions of 2H labels are close to 1 : 1. The angular distortions expected from repulsive interactions of the methyl groups in 11 and from cyclobutane annulation in 12 do not affect the relative energies of the bridged ions.
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    URL: http://dx.doi.org/10.1002/cber.19911240137
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    Verschiedenartige Koordinationen bei η2-Alken)-(η5-cyclopentadienyl)organylnickel(II)-Komplexen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 441-452 
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    ISSN: 0009-2940
    Keywords: (η2-Alkene)(η5-cyclopentadienyl)organylnickel(II) complexes, stability and reactivity of ; Cyclopentadienyl ligands, substituted ; Chelating alkenylcyclopentadienyl ; Nickel complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various Coordinations in (η2-Alkene)(η5-cyclopentadienyl)organylnickel(II) ComplexesA series of (η2-alkene)(η5-cyclopentadienyl)organylnickel(II) complexes with substituted cyclopentadienyl ligands is synthesized in order to compare the structures, the thermal stabilities, and chemical reactivities. In (allyl)(η5-Cp')Ni compounds the allyl moiety is η3-coordinated when Cp'=C5H5, C5Me5 (1), C5Ph5 (2), indenyl (3), [Hydridotri(pyrazolyl)borato] (4) (as an equivalent of the cyclopentadienyl ligand), and [C5H4((CH2)3CH=CH2)] (22). It is found that the [(η2-alkene)alkyl(η5-Cp')nickel] compounds [Cp'=C5Me5; alkene=C2H4, alkyl=Me (10), Et (9) or alkene=(1 - 2-η2)-1,3-butadiene, alkyl=Me (11); Cp'=C5Ph5; alkene=C2H4, alkyl=Me (12)] are thermally more stable and less reactive than their η5;- C5H5 analogues; the largest increase in thermal stability is observed when the η5-Cp' and the η2-alkene functions are connected by substitution of the cyclopentadienyl ligand with an alkenyl group of suitable chain length. In the case of compounds of the general type [(η5-C5R4((CH2)nCH=CH2))-(ligand)Ni(II)] with Ph3P as the ligand these complexes are cationic [R=H, n=3 (14+) or R=Me, n=2 (17+)]. On the other hand, the compounds with anionic ligands are neutral complexes (R=H, n=3, ligand=methyl (19), ethyl (20), isopropyl (21) or R=Me, n=3 and ligand=iodide (24), bromide (25), methyl (26), ethyl (27)]. In 14+, 17+, 19 - 21 and 24 - 27 the C=C bond of the alkenyl group is η2-coordinated to the nickel atom. X-ray structures have been determined for 4 and 25.
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  • 138
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    Medizinisch interessante Metallchelate, I. 99mTc-Komplexe mit sechszähnigen Tribrenzkatechin-Liganden (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 481-486 
    Details
    ISSN: 0009-2940
    Keywords: Tris[3-(2,3-dihydroxyphenoxy)propyl]amine hydrochloride containing ; 99mTc uptake ; Technetium, radiopharmaceutical ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Chelates of Medical Interest, I. - 99mTc Complexes with Hexadentate Tricatechol LigandsThe tricatechol ligand tris[3-(2,3-dihydroxyphenoxy)propyl]-amine hydrochloride, TRIPACE (9), is prepared from tris(3-chlorpropyl)amine (5) and the potassium salt of 2,2-dimethyl-1,3-benzodioxol-4-ol (7). This ligand is capable of reducing the 99m[TcO4]- ion to lower valent 99mTc and subsequent complexation of the reduced 99mTc ion. The structures of 5 and of tris[3-(2,2-dimethyl-1,3-benzodioxol-4-yloxy)propyl]amine (8) are determined by X-ray diffraction.
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  • 139
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    Steuerung der Aggregation von Mangankomplexen durch unterschiedliche Basen an den Beispielen [Mn(O2CCF3)2(py)4] und [Mn3(O2CCF3)6(benz)6] (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 515-517 
    Details
    ISSN: 0009-2940
    Keywords: Manganese complexes ; Aggregation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influencing the Aggregation of Manganese Complexes by Different Bases: Formation of [Mn(O2CCF3)2(py)4] and [Mn3(O2CCF3)6(benz)6]Manganese powder reacts quantitatively with trifluoroacetic acid to yield Mn(O2CCF3)2 (1). The aggregation of 1 is directed by different N-containing bases. Pyridine (py) forms the mono-nuclear complex [Mn(O2CCF3)2(py)4] (2), while benzonitrile (benz) yields the trinuclear complex [Mn3(O2CCF3)6(benz)6] (3). The X-ray structures of 2 and 3 are described.
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  • 140
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    Darstellung von [Dimethylamino(thiocarbonyl)thioamido]titan(IV)-dihalogeniden - Verbindungen mit kurzen Ti - N-Bindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 523-526 
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    ISSN: 0009-2940
    Keywords: Titanium complexes ; Short bonds, Ti - N ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of [Dimethylamino(thiocarbonyl)thioamido]titanium(IV) Dihalides - Compounds with Short Ti - N BondsReaction of Me2NC(S)SN(SiMe3)2 (1) with TiCl4 and TiBr4 yields (2) and (3). Treatment of 2 and 3 with pyridine (py) leads to the solvates · 3 py [2a (X=Cl), 3a (X=Br)]. These adducts have been characterized by X-ray structure determination.
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  • 141
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    The Conformational Behaviour of 10-Substituted Spiro[4.5]decanes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 551-561 
    Details
    ISSN: 0009-2940
    Keywords: Conformational analysis ; Spiro[4.5]decanes ; Allylboration, transition state models ; Ketals, chiral, cleavage by Lewis acids ; Calculations, MNDO and SYBYL ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behaviour of 10-X-substituted 1,4-dioxa-and 1,4,6-trioxaspiro[4.5]decanes 1 - 4 has been studied by 13C-, 19F- and 1H-NMR spectroscopy. Two X-ray analyses (of 2a,e) are presented, and their implications to cleavage reactions of chiral acetals are discussed. Participation of twist boat forms in the conformeric equilibrium of at least 1c has been made plausible by observing 13C,19F-NMR coupling constants. The ratios of axial to equatorial conformer in 1 - 4 have been calculated by molecular mechanics.
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    Darstellung von dreikernigen Carbonylmanganaten sowie deren Reaktionsprodukten mit InCl3; Röntgenstrukturanalysen von K3[Mn3(μ-CO)2(CO)10], [(C6H5)4As]2[(μ-H)Mn3(μ-CO)10], [{(C6H5)3P}2N]2[μ-H)Mn3(CO)12], [(C6H5)4As]2[{μ-H)Mn3(CO)12}2(μ4-In)] und [(C6H5)4As]2[{(μ-H)Mn3(CO)12}(μ3-In){Mn(CO)5}Cl] (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 453-463 
    Details
    ISSN: 0009-2940
    Keywords: Manganates, carbonyl, trinuclear ; Indium-manganese clusters ; Spiro cluster ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Trinuclear Carbonylmanganates and Their Reaction Products with InCl3; X-ray Structure Determinations of K3[Mn3(μ-CO)2(CO)10], [(C6H5)4As]2[(μ-H)Mn3(μ-CO)10], [{(C6H5)3P}2N]2[μ-H)Mn3(CO)12], [(C6H5)4As]2[{μ-H)Mn3(CO)12}2(μ4-In)] und [(C6H5)4As]2[{(μ-H)Mn3(CO)12}(μ3-In){Mn(CO)5}Cl]Mn2(CO)10 reacts with KOH in aqueous solution to give the potassium carbonylmanganate K3[Mn3(μ-CO)2(CO)10] (1). The trianion 1 is isoelectronic with Fe3(CO)12 and is protonated with methanol to form the μ-hydrido cluster [(μ-H)Mn3;-(CO)12]3⊖, which is precipitated with [{(C6H5)3P}2N]Cl as [{(C6H5)3P}2N]2[(μ-H)Mn3(CO)12] (2), whereas the carbonyl-bridged μ-hydrido species [(μ-H)Mn3(μ-CO)2(CO)10]2⊖ seems to be trapped as the [(C6H5)4As]⊕ salt 3. The reaction of 3 with InCl3 yields the Mn-In clusters [(C6H5)4As]2[{(μ-H)Mn3(CO)12}2;-(μ4-In) (4) and [(C6H5)4As]2[{(μ-H)Mn3(CO)12}(μ3-In){Mn(CO)5}Cl] (5). X-ray structure analyses have been carried out for the compounds 1 - 5.
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    Neue σ2λ3-P=C - O-Systeme: Stabile nichtkonjugierte Phosphaalkenether - Synthese und Reaktionen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 493-496 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkene ethers ; 1,3-Oxaphospholes, dihydro- ; 1,3-Oxaphosphorines, tetrahydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New σ2λ3-P=C - O Systems: Stable Non-Conjugated Phosphaalkene Ethers - Synthesis and ReactivityNon-conjugated cyclic phosphaalkene ethers (2, 4, 6) are obtained by cyclocondensation of (2- or 3-hydroxyalkyl)phosphanes 1, 3 with N-arylpivalimidoyl chlorides. Hydrolysis of 2, 4 with H2O (→7, 8), addition of hydrogen compounds (HCl, HSPh, MePhPH) (→ 9-12), and oxidation with air (→ 14) are studied. The reactivity of the title compounds and of benzoxaphospholes are compared.
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    Verhalten von cis;-2-Boryl-1-stannylalkenen gegenüber (Dimethylamino)trimethylstannan, Methoxytrimethylstannan und Methanol - Aufbau neuer Zinn - Element-Bindungen, Beispiele für Lösungsmittel-gesteuerte Reaktionen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 503-508 
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    ISSN: 0009-2940
    Keywords: cis;-2-Boryl-1-stannylalkenes ; Addition reactions ; Exchange reactions ; Solvent-controlled reactions ; Tin - Element bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Behaviour of cis;-2-Boryl-1-stannylalkenes Against (Dimethylamino)trimethylstannane, Methoxytrimethylstannane, and Methanol - Formation of New Tin - Element Bonds, Examples of Solvent-Controlled ReactionsWhen alkene derivatives1 [Me3Sn(R1)C=C(R)BR2], with the trimethylstannyl- and the dialkylboryl group in cis position at the C=C double bond, are treated with (dimethylamino)-trimethylstannane (4), methoxytrimethylstannane (5), or methanol, the product distribution depends remarkably on the solvent [hexane or tetrahydrofuran (THF)]. In hexane, 1a, b (R1=H, R=Et, Pr) react with 4 to give the B-dimethylamino compounds 6a, b in high yields as a result of addition and rearrangement. Other derivatives 1 do not react with 4 in hexane. Under the same conditions in hexane some alkenes 1 react with 5 to yield the B-methoxy derivatives 8, which are analogous to 6. A complex mixture of various products is obtained from the reaction of 1 with methanol in hexane. If the same reactions are carried out in THF, many compounds 1 react with 4 and 5 to eliminate tetramethyltin and give dihydro- 1,2,5-azonia- (7) or dihydro-1,2,5-oxoniastannaboratoles (9), respectively. The reaction with methanol in THF also leads to the oxonia-stannaboratoles 9, this time by elimination of methane. Pure samples of compound 9g are obtained as the crystalline THF adduct 9g-THF. A mechanism is proposed involving adduct formation at the boryl group, followed by intramolecular reactions depending on the donor quality of the respective solvent.
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    A Macrocyclic Tetraazapolyene - Synthesis and Configuration (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 671-672 
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    ISSN: 0009-2940
    Keywords: Azines ; Bis(azines) ; Macrocycles ; Tetraazapolyenes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new macrocyclic bis(azine) 2 forming yellow microcrystals has been prepared in 72% yield by treating the diketone 1 with hydrazine hydrate under high-dilution conditions. In contrast to the UV/Vis spectrum of the “open-chain” azine 4, that of 2 shows characteristic features of a polyene chromophore containing (Z)-configurated double bonds.
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    URL: http://dx.doi.org/10.1002/cber.19911240335
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  • 146
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    Cyclische Metall(IV)-amide (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 683-689 
    Details
    ISSN: 0009-2940
    Keywords: Metallacycles ; Titanium complexes ; Vanadium complexes ; Chromium complexes ; Amides, silylated ; Electrochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic Metal(IV)AmidesSynthesis and structure of cyclic amide complexes of quadrivalent titanium, vanadium, and chromium are described, and their electrochemical behavior is investigated by cyclic voltammetry. The novel amides of formula ML2 {M=Ti, (3b); M=V, (3c); M=Cr, (3d); L=[(CH3)3SiNCH2CH2NSi(CH3)3]} are formed by reaction of the halide adducts MCl3(THF)3 with the dilithium salt Li2L with concomitant disproportionation. Formation of 3d proceeds via the complex [3 d]⊖ and requires additional oxidation with oxygen or iodine. An X-ray crystalstructure determination of 3b reveals the titanium atom in strongly distorted tetrahedral environment with approximate symmetry D2d. The amide complexes 3b -d are monomeric, thermally stable, and sublime readily without decomposition; they are very sensitive to water and soluble in all common organic solvents.
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    On the Reactivity of [(Mes)Os(CO)Cl2] Toward Grignard Reagents. Unexpected Formation and X-ray Crystal Structure of [(Mes)Os(cyclohexene)(CO)] (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 707-712 
    Details
    ISSN: 0009-2940
    Keywords: Osmium mesitylene complexes ; Os - R bonds, formation of ; Osmium aryl hydrido compounds ; Cyclohexene, generation from C6H11MgX ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of [(Mes)Os(CO)Cl2] (3) with PhLi in benzene gives the diphenylosmium compound [(Mes)OsPh2(CO)] (6) whereas with PhMgBr [(Mes)OsPh(CO)Br] (7) is obtained. Treatment of 3 with TolMgBr in benzene or ether affords almost exclusively the monoaryl complex [(Mes)OsTol(CO)Br] (8). Compound 3 reacts with C6H11MgCl to give both [(Mes)Os(C6H11)2(CO)] (9) and [(Mes)Os(C6H10)(CO)] (10) in 60 and 30% yield, respectively. With C6H11MgBr, complex 10 is mainly obtained. Reaction of 7 and 8 with Na/Hg in THF/EtOH gives nearly quantitatively the arylhydridoosmium complexes [(Mes)Os-C6H4R(CO)H] (14, 15). The analogous hydrido methyl compound [(Mes)OsCH3(CO)H] (13) reacts with CCl4 to produce [(Mes)OsCH3(CO)Cl] (17), which is not accessible from 3 and LiCH3 or CH3MgX. The X-ray structure analysis of 10 reveals that the cyclohexene is coordinated in the endo configuration.
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    Synthese von Imidodiphosphaten des Aluminiums, Galliums, Indiums, Zinns und Titans (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 753-756 
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    ISSN: 0009-2940
    Keywords: Metal chelates ; Tetrachloroimidodiphosphates of Al, Ga, In, Sn, Ti ; Metallaheterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Imidodiphosphates of Aluminum, Gallium, Indium, Tin, and Titanium.Me3SiN[P(O)Cl2]2, (1) and Me3SnN[P(O)Cl2]2 (2) are synthesized from NaN[P(O)Cl2]2 and Me3SiCl or Me3SnCl, respectively. Treatment of 1 with AlCl3, GaCl3 InCl3, Me2SnCl2, and TiCl4 yields (3), (4), (5), (6), and (7), respectively. Reaction of LiN[P(O)Ph2]2 with TiCl4 leads to (8). NMR spectra demonstrate that the tetrachloroimidodiphosphate ligand coordinates through the oxygen atoms towards the metal atom.
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    Synthese und Struktur von Ph3P=NRe(NC6H3iPr2;-2,6)3 -eine Aza-Rhenium(VII)-Verbindung (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 757-759 
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    ISSN: 0009-2940
    Keywords: Rhenium(VII) ; Aza compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Ph3P=NRe(NC6H3iPr2;-2,6)3 - An Aza-Rhenium (VII) Compound.Ph3PNReO3 (1) reacts with three equivalents of 2,6-diisopropylphenyl isocyanate with evolution of CO2 to give the title compound 2. The X-ray single crystal structure of 2 exhibits a rhenium atom tetrahedrally coordinated to four nitrogen atoms (space group P 3).
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    URL: http://dx.doi.org/10.1002/cber.19911240413
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    Zur Reaktivität des Silaethens Me2Si=C(SiMe3)2: Stereospezifität der Diels-Alder-Reaktionen mit Hexadienen1,2 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 769-771 
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    ISSN: 0009-2940
    Keywords: Silaethene ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reactivity of Silaethene Me2Si=C(SiMe3)2: Stereospecificity of Diels-Alder Reactions with Hexadienes1,2)[4 + 2] Cycloaddition of trans,trans;- and cis,trans;-2,4-hexadiene to silaethene Me2Si=C(SiMe3)2 (1) takes place stereo-specifically in one step with formation of 3 and 4, respectively. In addition, both reactions lead to ene products 5, 6.
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    Decacarbonyl(μ3;-η2-‖-1,4-dimethoxy-2-butyne)triiron, an Iron Cluster with Unusual Structure (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 773-775 
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    ISSN: 0009-2940
    Keywords: Alkyne complexes ; Clusters ; Iron complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of undecacarbonyl(acetonitrile)triiron (1) with 1,4-dimethoxy-2-butyne (2) yields the alkyne complexes decacarbonyl(μ3;-η2-Verbar-1,4-dimethoxy-2-butyne)triiron (3) and nonacarbonyl(μ3;-η2;-⊥-1,4-dimethoxy-3-butyne)triiron (4). The crystal structure determination of 2 shows that the alkyne ligand is coordinated strictly parallel to one iron-iron edge.
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    Small and Medium Rings, 75. Syntheses, Photoelectron Spectra, and Photoreactivity of Polycyclic 1,5-Diketones: Transannular Interaction in the Cyclooctane-1,5-dione Fragment (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 803-813 
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    ISSN: 0009-2940
    Keywords: PE spectroscopy ; Lone-pair interaction ; Orbitals, localized ; Orbitals, precanonical ; 1,5-Diketones, polycyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five polycyclic 1,5-diketones 1 - 4 and 6 are synthesized and studied by means of He(Iα) PE spectroscopy. Comparison of the spectra indicates significant differences in Orbital Interaction Through Bond, which is explained by computational methods, especially by analyses of the precanonical MOs. The lone pair splitting observed in diketone 1, ΔI(n)=0.75 eV, seems to be the largest one ever found in a 1,5-diketone, obviously due to a favourable zigzag topology of the σ frame. In addition, coupling reactions and photoreactivity are studied in compound 6, which seemed to be well suited for Orbital Interaction Through Space. The crystal structure of 6 and its photoproduct 21 is solved by X-ray crystallography.
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    URL: http://dx.doi.org/10.1002/cber.19911240421
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    Chromophore Systeme, 2. Konformation und Lichtabsorption von (2-Alkoxyvinyl)ethandionen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 827-832 
    Details
    ISSN: 0009-2940
    Keywords: Conformations, solid state ; Conformers in solution ; UV-Vis transition energies and CO/CO dihedral angles ; CO/CO rotational barriers ; Calculations, CNDO/S-CI, MMP1, PIMM / PE spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromophoric Systems, 2. - Conformation and Absorption of Light in (2-Alkoxyvinyl)ethanedionesThe unusual color properties of yellow 1,2-bis(4,5-dihydrofuran-3-yl)ethane-1,2-dione (1) and colorless 1,2-bis(5,6-dihydro-4H-pyran-3-yl)ethane-1,2-dione (2) in the solid state and in solution are investigated by crystal structure analysis, UV-Vis, PE, and 13C-NMR spectroscopy as well as by reparameterized force-field calculations. Dione 1 takes an antiperiplaner CO/CO conformation of its chromophore in the solid state whereas dione 2 is twisted in this respect by 102°. In solution both chromophores are not planar, but 1 is less distorted (ca. 142°) than dione 2 (ca. 126°). The calculated rotational barrier for CO/CO twisting amounts to 0.9 kcal mol-1 for 1 and to 2.2 kcal mol-1 for 2.
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    URL: http://dx.doi.org/10.1002/cber.19911240424
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    Diels-Alder Reactions of Sulfur-Substituted Allenecarboxylates An FMO Approach by the PM3-Method (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 867-873 
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    ISSN: 0009-2940
    Keywords: Diels-Alder reaction ; Captodative effect ; Calculations, MNDO-PM3 ; Allenic dienophiles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of captodative (c,d) substitution of some olefins and allenes has been investigated by MNDO-PM3 calculations. These results are compared with the Diels-Alder reactions of α-sulfur-substituted allenecarboxylates. α-Sulfonyl allenecarboxylates 6 are a new class of stable gem-diacceptor-substituted allenes.
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    Ozonolysen von α-Oxo-alkenen: Zur Existenz von α-Oxo-ozoniden (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 947-956 
    Details
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Alkenes ; α-Oxo- ; 1,2,4-Trioxolanes ; acyl- ; 3,3′-Bi-1,2,4-trioxolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ozonolyses of α-Oxo-alkenes: On the Existence of α-Oxo-ozonidesOzonolyses of nine acyclic (1a-i) and of two cyclic (14, 29) α-Oxo-alkenes on polyethylene or in pentane afforded in eight cases (1d-i, 14, 29) isolable α-Oxo-ozonides. α-Diozonides (9) are obtained from five of the acyclic α-Oxo-alkenes (1a, b, d, g, h). All isolated ozonides are labile; the 2,4-dinitrophenylhydrazones of the α-Oxo-ozonides, however, are very stable. Decomposition of the α-Oxo-ozonides affords not only the hitherto known fragments, but non-peroxidic isomers (8) of the ozonides, too.
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    Sterische Behinderung der Isocyanid-Cyanid-Umlagerung in einer Brückenkopfposition (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 971-972 
    Details
    ISSN: 0009-2940
    Keywords: Isocyanide-cyanide rearrangement ; Bridgehead reactivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steric Hindrance of the Isocyanide-Cyanide Rearrangement in a Bridgehead PositionThe activation barrier of the isocyanide-cyanide rearrangement of 13-isocyano-1,4,5,8,9,12-hexamethyltriptycene (5) is the highest of all known isocyanides. The special position of this compound can be explained by a strong increase of strain enthalpy during the isomerization. This is due to the cage-like inclusion of the isocyano group in the bridgehead position by the methyl groups in the positions 1, 8, and 9.
    Additional Material: 2 Tab.
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    übergangsmetall-substituierte Acylphosphane und Phosphaalkene, XV. Zur Umsetzung des Phosphaallylkomplexes (η5-C5Me5)(CO)Fe-{η3-P[CH(SiMe3)2](CHC=O)} mit Chalcogenen und Fe2(CO)9 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 989-996 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaallyl complexes ; Chalcogenes ; Düron, enneacarbonyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, XV. - Reaction of the Phosphaallyl Complex (η5-C5Me5)(CO)Fe{η3-P[CH(SiMe33)2](CHC=O}} with Chalcogenes as well as with Fe2(CO)9The (η3-phoshaalyl)iron complex (η5-C5Me5)(CO)Fe{η3-P(CH(SiMe3)2](CHC=O)} (1) is oxidized by sulfur and selenium to afford the methylenethioxo- and methyleneselenoxophosphorane complexes 4 and 5 with an anti-configuration of the CH(SiMe3)2 substituent relative to iron. The chalcogene atoms are attached to the phosphorus atom of the ligand and do not participate in the bonding to the metal Equivalent amounts of 1 and Fe2(CO)9 lead to the phosphaalkenyl complex 6 with an Fe - C σ bond. On the other hand, a large excess of Fe2(CO)9 converts 1 as well as 6 into the cluster compound 7 featuring the bridging 1-oxa-4-phosphabutadiene ligand (η5-C2Me5)(CO)2Fe - C(O) - CH=P - CH(SiMe3)2. Constitution and configuration of all compounds have been elucidated by spectroscopic methods (IR, 1H, 13C, 31P NMR, and MS). In addition complexes 5 and 7 have been characterized by single crystal X-ray diffraction analyses.
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    Synthese eines chiralen, nicht-racemischen Aziridinons (α-Lactams)1,2) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 849-859 
    Details
    ISSN: 0009-2940
    Keywords: tert-Leucine ; Diazotation ; Butanoic acid, (S)-2-chloro-3,3-dimethyl-, and derivatives ; Aziridinones ; α-Lactams ; Amino acids, α-alkyl-, and esters ; Oxazolidine-2,5-diones ; Circular dichroism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Chiral, Nonracemic Aziridinone (α-Lactam)1,2)(S)-tert-Leucine [(S)-14] is diazotized affording a mixture of the expected α-chloro and α-hydroxy acids (S)-15 and (S)-16 and the rearranged β-chloro and β-hydroxy acids (R)-12 and (S)-11. Separation produces a 51% yield of pure (S)-15 (e.e. ° 97.4%) which is converted via the acid chloride (S)-17 into the α-chloro amides (S)-18a and b (e.e.=99.0 and 95.2%, respectively). On treatment with tBuOK, the latter is converted into the α-lactam (R)-22b (59%, e.e. ° 91.0%, [α°=-293.7), which is accompanied by small amounts of its ring-opening product (R)-23b. Only the α-amino ester (R)-23 a is formed from the α-chloro amide (S)-18a and tBuOK. While the enantiomers of the halo amides 13, 18a, b, 24a, b and of the 3-pentyl esters of the hydroxy acid 16 are separated by GC on chiral columns, the α-lactam 22b and the α-amino esters 23a, b require conversion into separable derivatives without involving the stereogenic center. Thus, alkaline hydrolysis of 22b as well as acidic cleavage of 23 yield the α-amino acids 25 which are cyclized to the oxazolidine-2,5-diones 26 by means of bis(trichloromethyl) carbonate (“triphosgene”). As shown by the high enantiomeric excess of the products derived from (S)-tert-leucine [(S)-14] none of the reactions described results in a considerable degree of racemization. Authentic samples of 11 and 12 are synthesized from the Reformatzky product 21. The absolute configurations of the major enantiomers derived from (S)-14 are based on the retention on chiral GC columns, the signs of optical rotations, and CD spectra. The mechanism of the rearrangement leading to the β-hydroxy and β-chloro acids (S)-11 and (R)-12 is interpreted in terms of a stereospecific 1,2-methyl shift occurring simultaneously with the ring cleavage of the (protonated) α-lactone (R)-2 (R=tBu) which is the crucial intermediate formed in the diazotization of (S)-14.
    Additional Material: 7 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240427
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    Diazadienkomplexe elektronenarmer übergangsmetalle: Synthese, Eigenschaften und Struktur von CpTi(diazadien)Cl (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1035-1039 
    Details
    ISSN: 0009-2940
    Keywords: Titanium complex ; Diazadiene ligand ; Envelope structure ; Benzyl compound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diazadiene Complexes of Electron-Deficient Transition Metals: Synthesis, Properties, and Structure of CpTi(diazadiene)ClThe electron-deficient 1,4-diazadiene (DAD) complex CpTi-(DAD)Cl (3), [DAD=1],4-bis(4-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene] is prepared either by reduction of CpTiCl3 (1) with magnesium in the presence of free DAD (2) or by the reaction of 1 with Na2DAD. NMR spectroscopic and X-ray diffraction analysis of 3 indicate that the bonding of the DAD ligand has σ2,π-metallacyclopentene rather than η4;-π character. As a result of steric repulsion between the Cp ring and methyl groups of the DAD ligand 3 exhibits a supine (exo) geometry for DAD coordination is solid state. Substitution reaction of 3 affords the novel complex CpTi(DAD)R (R=CH2Ph).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240509
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    Photolysis of Diazo(pentamethyldisilanyl)methyl Ketones in the Presence of Carbonyl Compounds: Trapping of the Acylsilene IntermediatesDedicated to Professor Paul Binger on the occasion of his 60th birthday. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1295-1300 
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    ISSN: 0009-2940
    Keywords: Diazo compounds ; Carbenes ; Silaethenes ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: UV photolysis of diazo(pentamethyldisilanyl)methyl ketones 1b - d generates acylsilenes (3-oxo-1-sila-1-propenes) 3 as reactive intermediates, which can be trapped by enolizable carbonyl compounds in an ene-type reaction. With non-enolizable carbonyl compounds or ethyl acetate, they undergo a [4 + 2] cycloaddition. In contrast to the photolysis in the absence of these carbonyl compounds, a Wolff rearrangement of 1b - d (or the derived carbenes) to silyl ketenes 5b - d is observed as a competitive reaction.
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    URL: http://dx.doi.org/10.1002/cber.19911240549
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    Lithium-(2,4,6-tri-tert-butylphenylselenid); Erzeugung, Struktur und Reaktionen unter Knüpfung von Se -P-, Se - C-, Se - Si-, Se - Sn- und Se - Au-Bindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1315-1320 
    Details
    ISSN: 0009-2940
    Keywords: Chalcogen-chalcogen bonds ; Selenium ; Selenide (2,4,6-tri-tert-butylphenyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Properties of Chalcogen-Chalcogen Bonds, XV1). - Lithium 2,4,6-Tri-tert-butylphenylselenide: Synthesis, Structure, and Reactions with Formation of Se - P, Se - C, Se - Si, Se - Sn, and Se - Au BondsBis(2,4,6-tri-tert-butylphenyl)diselenide (1) is reduced by lithium triethylhydridoborate to give lithium 2,4,6-tri-tert-butyl-phenylselenide (2) in high yield. 2 crystallizes with three molecules of tetrahydrofuran coordinated to lithium ([2(THF)3] ≡ 2a, space group P&1macr; Z =4). The monomeric compound 2a contains four-coordinate lithium bonded to two-coordinate selenium. 2 (LiSeR) reacts with the nonmetal and metal halides tBu2PCl, CH2Cl2, Me3SiCl, Me3SnCl, and Ph3PAuCl to give tBu2PSeR (3), RSeCH2Cl (4), (RSe)2CH2 (5), Me3SiSeR (6), Me3SnSeR (7), and the novel gold(I) selenophenolate derivative Ph3PAuSeR (8)(R = 2,4,6-tri-tert-butylphenyl).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240602
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    Reactions of Fluorophosphoranes with N,N,Ń-Trimethyl-N′-(trimethylsilyl)ethylenediamine - Intramolecularly Stabilized Azonium Hexafluorophosphates by Fluoride Abstraction from N,N,N′-Trimethylethylenediamine-Substituted Fluorophosphoranes with Phosphorus Pentafluoride1) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1335-1346 
    Details
    ISSN: 0009-2940
    Keywords: Fluorophosphoranes ; Donor-acceptor interaction ; Azonium salts ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of the tetrafluorophosphoranes RPF4 [R = CH3, C6H5, C6F5, (CH3)3SiCH2, and 2,5-(CH3)2C6H3] with N,N,Ń-trimethyl-N′-(trimethylsilyl))ethylenediamine (1) yields the corresponding triflurophosphoranes 2-6 by cleavage of the Si - N bond and elimination of (CH3)3SiF. In an analogous reaction the difluorophosphoranes R1R2PF2N(CH3)CH2CJ2N-(CH3)2 (R1 = R2 = C6H5, 7: R1 = C6H5, R2 = C4H4N, 8) are formed. Some of these N,N,Ń-trimethylethylenediamine-substituted di- and trifluorophosphoranes react with PF5 as a Lewis acid to form the corresponding azonium hexafluorophosphates 9-12 as a result of fluoride abstraction and intramolecular (CH3)2N→P donor-acceptor interaction. Compound 13 shows dynamic behaviour in solution. An exchange process is observed for the axial and equatorial fluorine atoms by 19F- and 31P-NMR spectroscopy. An X-ray structure analysis of the compounds 10 - 12 reveals the expected trigonal-bipyramidal geometry at phosphorus. The ethylenediamine ligand is found to form a chelate ring, whereby one axial and one equatorial site are bridged. The coordinative P - N bonds are very long (up to 207 pm).
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    Synthese von 6,7,8,9,15,16,17,18-Octahydrodibenzo[f,m][1,8,4,11]- dithiadiazacyclotetradecin-8,17-diessigsäure (H2L1); Strukturen entsprechender Kupfer-Komplexe (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1357-1362 
    Details
    ISSN: 0009-2940
    Keywords: Copper complexes ; Macrocyclic ligands, N-functionalized ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: trans-N2S2-Macrocyclic Ligands with Pendant Carboxylic Groups. - Synthesis of 6,7,8,9,15,16,17,18-Octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine-8,17-diacetic Acid (H2L1); Structures of Corresponding Copper ComplexesThe macrocyclic ligand with pendant carboxylic groups 6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine-8,17-diacetic acid (H2L1) and its Ni(II) and Cu(II) complexes, [NiL1]3(H3O·ClO4)4·H2O (1) and [Cu(HL1)]ClO4·1.5 H2O (2), have been prepared. The coordination properties of H2L1 towards Ni(II) and Cu(II) in aqueous solutions are independent on the pH according to UV/Vis-spectral measurements. The structures of 2 and of [CuL2]ClO4 (3) with HL2 = 6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclodetradecine-8-acetic acid have been determined by X-ray crystallography. In 2, all six donor atoms of the ligand are coordinated, forming an octahedron. Due to their size the metal atoms are not incorporated in the ligand cavity. The ligand is folded in such a way, that the N-donor atoms are in trans, and the S-(and O-)donor atoms in cis positions. In 3, the five donor atoms form a rather regular bipyramid with the N atoms in the axial positions. The stereochemistry of the ligands in the complexes 2 and 3 is discussed.
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    Organolanthanid(II)-Chemie: Synthese und Struktur von [Cp2*Sm(μ-OC)2FeCp*]2 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1373-1375 
    Details
    ISSN: 0009-2940
    Keywords: Samarium complexes ; Iron complexes ; Lanthanides, organo- ; Heterodimetallic complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organolanthanide(II) Chemistry: Synthesis and Structure of [Cp*Sm(μ-OC)2FeCp*]2The tetranuclear complex [Cp*Sm(μ-OC)2FeCp*]2 (3) has been prepared by reaction of Cp*2Sm(THF)2 with [Cp*Fe(CO)2]2 and structurally characterized by single-crystal X-ray diffraction.
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    URL: http://dx.doi.org/10.1002/cber.19911240611
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    The 2,4-Bis(diphenylmethylene)-1,3-cyclobutane-dione Diradical Dianion and its Sulphur Analogues2) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1397-1402 
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    ISSN: 0009-2940
    Keywords: Cyclobutane-1,3-diones ; Cyclobutane-1,3-dithiones ; Radical anions ; Diradical dianions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4-Bis(diphenylmethylene)-1,3-cyclobutanedione (1) is transformed into its sulphur analogues 2 and 3 with Lawesson's or Davy's reagent 5a,b. An X-ray structural analysis is performed on 3. The electrochemistry of these compounds is surveyed. The products of the electrochemical reduction exhibit ESR spectra, which could not be attributed to the radical anions 1-•, 2-•, and 3-•. Extensive semiempirical AM1/Cl calculations suggest the spectra to correspond to the diradical dianions. The experimental data are discussed in terms of the theoretical results.
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    URL: http://dx.doi.org/10.1002/cber.19911240613
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    Cycloadditions, 34. Donor-Substituted Allenes in Diels-Alder Reactions with Inverse Electron Demand (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1425-1429 
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    ISSN: 0009-2940
    Keywords: Allenes ; Hetero Diels-Alder reactions ; Catalysis, heterogeneous ; Glutaraldehyde ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several cycloaddition reactions of 1-alkoxy-1,2-propadienes 1 with 1-oxa-1,3-dienes 2, catalyzed by acid-free silica gel, are described. The resulting 3,4-dihydro-3-methylene-2H-pyrans 3 are transformed into synthetically interesting glutaraldehyde derivatives 10 - 13.
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    Fluorthiatriazine (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1347-1352 
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    ISSN: 0009-2940
    Keywords: 1α4,2,4,6-Thiatriazines, preparation, structures ; 1α4,2,4,6-Thiatriazinium cations ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: FluorothiatriazinesFrom the reaction of (ClCN)2(ClSN) (1) with AgAsF6 in liquid SO2 (ClCN)2(SN)⊕ AsF⊖06 (2) is obtained in quantitative yield. With CsF 2 gives (ClCN)2(FSN) (3), which slowly dismutates at room temperature to form (ClCN)(FCN)(FSN) (4) and 1. Fluorination of 1 with SbF3 yields (FCN)2(FSN) (5). With AsF5 5 forms the salt (FCN)2(SN)⊕ AsF⊖ (6). The cation of 6 is transformed by NOCl or CsBr into the corresponding neutral derivatives (FCN)2(ClSN) (7) and (FCN)2(BrSN) (8), respectively. The gas-phase structure of 5 was determined by electron diffraction. The influence of the different exocyclic substituents on the bond properties in this ring system is explained by means of MNDO calculations.
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    Dirhenioethin (OC)5Re-C≡C-Re(CO)5 als Baustein zum Aufbau von Carbonyl-Metall-ClusterverbindungenHerrn Professor Paul Binger zum 60. Geburtstag gewidmet. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1363-1368 
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    ISSN: 0009-2940
    Keywords: μ-(Ethynediyl)bis(pentacarbonylrhenium) ; Acetylide-bridged carbonyl metal clusters ; Iron carbonyl complexes ; Cobalt carbonyl complexes ; Platinum carbonyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dirhenioethyne (OC)5Re-C≡C-Re(CO)5 as Building Block for the Synthesis of Carbonyl Metal ClustersThe dimetallated ethyne (OC)5Re-C≡C-Re(CO)5 (1) reacts with (Ph3P)2Pt(η2-C2H4), Fe2(CO)9, and Co2(CO)8 to give the acetylide-bridged complexes PtRe2(μ3-η1:η1:η2-C≡C)(CO)9-(PPh3)2 (2), FeRe2(μ3-μ1:η1:η2-C≡C)(CO)13 (3), and Co2Re2-(μ4-η1:η1:η2:η2-C≡C)(CO)14 (4), resp., whose structures have been determined by X-ray diffraction. These reactions of (CO)5Re-C≡C-Re(CO)5 proceed similarly to those of the isolobal organic acetylenes, but with formation of metal-metal bonds.
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    Synthesis and Thiophene Ring Opening Reaction of [2]Paracyclo[2](2,5)-and -(2,4)thiophenophanes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1403-1409 
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    ISSN: 0009-2940
    Keywords: Paracyclothiophenophane ; Photodesulfurization ; Pyrolysis ; Reductive ring opening reaction ; [n] Paracyclophane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dithia[3]paracyclo[3](2,4)- and -(2,5)thiophenophanes 〈dithia-[3.3](2,4)- and -(2.5)PTP〉 (3, 7, 9) are obtained by the coupling reaction of the corresponding bis(chloromethyl)- and bis(mercaptomethyl)arenes. Desulfurization of the dithia[3.3]PTPs 3, 7, 9 by photolysis affords the thia[2.3]PTPs 15, 16, 17 and [2.2]PTPs 14, 18, 19, 20 The pyrolysis of the disulfone 12 gives the symmetrical thiophenophane 13. The dynamics of the ring inversion, the UV spectra, and the reductive ring opening with Raney-Ni (W-7) of the obtained PTPs are discussed.
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    URL: http://dx.doi.org/10.1002/cber.19911240614
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    On the Generation of Polycarbon Nitride Radicals CnN. (n = 2-5) by Neutralization-Reionization Mass Spectrometry (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1481-1483 
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    ISSN: 0009-2940
    Keywords: Interstellar chemistry ; Polycarbon nitride radicals ; Neutralization-reionization mass spectrometry ; Tandem mass spectrometry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title radicals, thought to be of prime importance in the genesis of interstellar organic molecules, are accessible in the gas phase by neutralization of the corresponding CnN+ ions (n = 2-5) using tandem mass spectrometry methods (neutralization-reionization mass spectrometry). Collision-induced dissociation reactions of mass-selected CnN+ are in keeping with the connectivity of a “carbon rod” bearing a nitrogen atom at one terminus.
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    Mehrstufige reversible Redoxsysteme, LIV. Leitfähige CT-Komplexe des Tetrathiafulvalens (TTF) mit Tetracyanchinodimethan (TCNQ) und N,N′-Dicyanbenzochinondiimin (DCNQI) - ein Vergleich (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1445-1451 
    Details
    ISSN: 0009-2940
    Keywords: Charge-transfer complexes ; Electrical conductivity ; Tetrathiafulvalenes ; Tetracyanobenzoquinodimethane ; Dicyanobenzoquinodiimine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LIV1). - Conducting CT Complexes of Tetrathiafulvalene (TTF) with Tetracyanobenzoquinodimethane (TCNQ) and N,Ń-Dicyanobenzoquinodiimine (DCNQI) - A ComparisonX-ray structure analysis and electrical conductivity together with ESR data of the CT complex DCNQI/TTF · 2 H2O (3/2 · 2 H2O) are presented and compared with those of the wellknown TCNQ/TTF (1/2).
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    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19911240701
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    Komplexierung von 1,3-Dihydro-1,3-diborapentafulven-Derivaten mit Fe(CO)3-Fragmenten: Synthesen, Kristall- und Elektronenstruktur von μ-(η4:η5-1,3-Dihydro-1,3-diborapentafulven)-bis (tricarbonyleisen)-Komplexen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1505-1509 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Diborapentafulvene ; Iron tricarbonyl complexes ; Slipped triple-decker ; Calculations, ab initio, EH ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of 1,3-Dihydro-1,3-diborapentafulvene Derivatives with Fe(CO)3 Fragments: Syntheses, Crystal and Electronic Structure of μ-(η4: η5-1,3-Dihydro-1,3-diborapentafulvene)-bis(tricarbonyliron) ComplexesReactions of the 1,3-diborapentafulvene derivatives 1a-c with (CO)3Fe(C8H14)2 lead to the violet dinuclear complexes 3a-c, which possess a slipped triple-decker structure. The X-ray structure analyses of 3b,c reveal that one Fe(CO)3 group is pentahapto-coordinated to the 1,3-diborole frame of C2B2C=C, whereas the other interacts with the Y-shaped B2C=C unit. The latter resembles the interaction of Fe(CO)3 with trimethylenemethane. An MO calculation indicates that the formation of 3 occurs by distortion of 1 · Fe(CO)3; the slippage of Fe(CO)3 from η5 to η4 bonding is followed by η5 coordination of the second Fe(CO)3 group.
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    Syntheses and Molecular Structures of an Isoelectronic Series of (2-Hetero-)1,3-Diphosphabenzenes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1525-1530 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Diphosphabenzene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, NMR spectra, and X-ray molecular structures of three (2-hetero-)1,3-diphosphabenzenes are reported which constitute an isoelectronic triade of compounds with BH2, CH, and N bridging units between the two phosphorus atoms. The remaining three carbon atoms of the rings are part of a 2-methallylic system. The 2-borataheterocycle 3 has been prepared by the reaction of CH2 = C(CH2)PPh2)2 (1) with Me2S—BH2Br to give an intermediate 2 still containing the exocyclic olefinic bond. Treatment of 2 with a base, deprotonation of one ring CH2 group, and proton migration from the other one to the olefinic CH2 group afford the 5-methyl-1λ5-phospha-3-phosphonia-2-boratabenzene 3. The PBP unit is tilted by 144.0(2)° against the planar C3P2 part of the ring. A heterocyclic precursor 4 for the carbon analog is generated from 1 and CH2I2, which on reaction with a strong base yields the diphosphabenzene 5 with a fully planar ring skeleton. For the synthesis of the aza analog 7, CH2=C(CH2Cl)2 is treated with HN(PPh2)2 to give the precursor 6, which can be deprotonatad at nitrogen and carbon with a base. In the crystals of 7, two independent molecules of very similar structure are present. The molecules show planar heterocycles.
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    Metallkomplexe mit biologisch wichtigen Liganden, LX. Metallkomplexe von 3′-Azido-3′-desoxythymidin (AZT) und 3′-Isocyan-3′-desoxythymidin (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1541-1548 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Palladium complexes ; Platinum complexes ; Rhodium complexes ; Iridium complexes ; 3′-Azido-3′-deoxythymidine ; 3′-Isocyano-3′-deoxythymidine ; Anti-HIV ; Antiinflammatory activity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LX.  -  Metal Complexes of 3′-Azido-3′-deoxythymidine (AZT) and 3′-Isocyano-3′-deoxythymidineMetal complexes of N-3-deprotonated 3′-azido-3′-deoxythymidine (AZT  -  H+), (AZT  -  H+)AuPR3 (R = Me, Et, Ph) (2, 3, 4), trans-(AZT  -  H+)2Pd(NH3)2 (5), [(n-Bu3P)(AZT  -  H+) M(μ-Cl)2M(AZT  -  H+)(n-Bu3P)] (M = Pd, Pt) (6, 7), trans-(Ph3P)2Pd(AZT  -  H+)2 (8), cis-(Ph3P)2Pt(AZT -  H+)(Cl) (9), and complexes of 3′-isocyano-3′-deoxythymidine (L), (Et3P)(L)- PdCl, (11), (12), (n-Bu3P)(L)PtCl2 (13), [(Ph3P)2(L)PtCl](BF4) (14), (η5-C5Me5)(L)RhCl2 (15), and (η5-C5Me5)(L)IrCl2 (16) have been prepared and characterized by IR and NMR spectra, 2 by X-ray crystallography. 2, 4, and 9 show an anti-HIV activity very similar to AZT; 2 exhibits antiinflammatory activity.
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    Fusing Cyclopentadiene and Ferrocene by Two Silyl Bridges Stereochemically Well-Defined Building Blocks for High-Nuclear Metallocenes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1531-1539 
    Details
    ISSN: 0009-2940
    Keywords: Ferrocenes ; Cyclopentadienes, disilyl- ; Silatropic rearrangement ; Lithium cyclopentadienides ; Metallocene, trinuclear, mixed-metal ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetrahydro-4,4,8,8-tetramethyl-4,8-disila-s-indacenyl anion (LH) reacts with or without cyclopentadienyl anion (Cp-) and Fe2Cl4(THF)3 to give the mixed ferrocenes CpFe(LH) and (LH)2Fe in 50 and 63% yield, respectively. Near room temperature and in solution CpFe(LH) exists as a pair of enantiomers (syn-3a/b). According to an X-ray analysis both enantiomers are present in a single crystal. Compound 3 consists of a ferrocene linked to a cyclopentadiene by two Me2Si groups such that the acidic Cp proton points towards the iron. Temperature-dependent NMR spectra show that syn-3a and syn-3b are non-rigid molecules which are interconverted by 1,2-silatropic bond shifts (Ea = 49.2 ± 2.9 kJmol-1). Three more isomers (anti-3a, anti-3b, and the spiro derivative 3c), though present only in low concentration, are engaged in the rearrangement. (LH)2Fe is also non-rigid and exists as a pair of diastereomers (4a and 4b). The isomers of 3 and 4 undergo hydrolysis (e.g., syn-3a/3b gives [(Me2SiOSiMe2)Cp]FeCp (5) among others) and deprotonation. The latter yields CpFe(L-) (7) and (L-)2Fe (8), which are characterized by NMR spectroscopy. 7 forms crystals with [Li(TMEDA)]+ as counterion, and an X-ray analysis shows that lithium and iron are located at opposite sides of the strongly folded ligand L. The reaction of 7 with CrCl2(THF) gives the trinuclear stacked metallocene 9 in 47% yield. 9 has two unpaired electrons which are located essentially in the center of the molecule.
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    Geminal-Dialkyl-Effect-Controlled Site Selectivity of Fe(I)-Mediated C — H/C — C Bond Activation of Aliphatic Ketones (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1679-1680 
    Details
    ISSN: 0009-2940
    Keywords: Bond activation, C — H, C — C ; Transition-metal ions ; Tandem mass spectrometry ; Geminal dialkyl effect ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Depending on the internal energy content, due to the operation of a geminal dialkyl effect, the Fe+ -mediated dehydrogenation of α,α-dimethyl-substituted ketones preferably involves the more substituted alkyl chain.
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    (1,1′,3,3′-Tetra-tert-butyl-5,5′-pentafulvalen) dithallium - Synthese und Kristallstruktur: Ein Beitrag zur Diskussion von nichtklassischen Thallium-Thallium-Wechselwirkungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1693-1697 
    Details
    ISSN: 0009-2940
    Keywords: Nonclassical T1(I)-T1(I) interactions ; Thallium, fulvalene complex ; (Cyclopentadienyl)thallium complex ; 5,5′;-Pentafulvalene, 1,1′;,3,3′;-tetra-tert-butyl-dithallium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (1,1′,3,3′-Tetra-tert-butyl-5,5′-pentafulvalene)dithallium - Synthesis and Crystal Structure: a Contribution to the Discussion of Nonclassical TI(I)-TI(I) InteractionsReaction of 1,1′,3,3′-tetra-tert-butyl-5,5′-dihydropentafulvalenediyldilithium with stoichiometric amounts of thallium chloride affords the dinuclear complex (η5:(η5-tBu4C10H4)Tl2 (2). Compound 2 is air-and moisture-sensitive, and photolabile. It crystallizes in the space group P•1 and consists of two (cyclopentadienyl)thallium units which are connected by a central C-C bond and twisted against each other by 70°. The monomeric units of 2 form a two-dimensional polymer with a zick-zack chain of T1 atoms and a periphery of substituted cyclopentadienyl ligands. Rather short T1-T1 contacts of 3.760 and 3.998 Å are formed within a dimeric substructure. The geometry of the cyclopentadienyl ligands around the shortest T1-T1 bond is similar to that predicted by the theory for weak T1-T1 interactions.
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    Synthesis, Structure, and Electronic Properties of Bis(tetramethylcyclopropylidene)methane and Bis(cyclopropylidene)methane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1591-1596 
    Details
    ISSN: 0009-2940
    Keywords: Allenes, highly strained ; Strain  -  structure correlation ; Hybridization effects, 13C, 13C coupling constants ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(tetramethylcyclopropylidene)methane (5) was prepared by treating 1-(dichloroethenylidene)-2,2,3,3-tetramethylcyclopropane (3) with tert-butyllithium in the presence of 2,3-dimethyl-2-butene. The parent allene 6 was obtained along a new route from bis(1-bromocyclopropyl) ketone (11) with low-valent titanium. Both 5 and 6 show unusually intense allene stretching bands in the IR spectra, and the signals of their central carbon atoms appear at remarkably high field in the 13C-NMR spectra. The unique structural features of 5 and 6, as evidenced by an X-ray crystal structural analysis of 5 and 1Jcc values, agree remarkably well with theoretical predictions made by semiempirical (MNDO) and ab initio (4-31G) calculations and on the basis of the simple picture offered by the hybridization model using the iterative maximum overlap (IMO) approach.
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    Structures of Tris(donor)-Tris(acceptor)-Substituted Benzenes, 2.Potassium Salts of Trinitrophloroglucinol (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1727-1731 
    Details
    ISSN: 0009-2940
    Keywords: Conformational analysis ; Benzene, donor-acceptor-substituted ; Benzene ring, distortion of ; Hydrogen bonding, intramolecular ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray crystallographic analysis of the mono-, di-, and tri-potassium salts 2b - d of trinitrophloroglucinol (2a) show their benzene rings to become considerably more distorted on successive deprotonation. A parallel increase in C - C, and a decrease in C - O and C - N bond lengths leading to a radialenetype structure is also observed. For 2b, two chemically different molecules are found in the crystal which differ in their hydrogen-bond pattern as well as in their average bond lengths and deviation of their benzene rings from planarity. AM1 calculations show that for 2b,d a multitude of structures, differing widely in the deviation of their benzene cores form planarity, can exist within a small energy range ( 〈 3 kcal/mol). The experimental and computational results are discussed in terms of a model that emphasizes “push-pull” interactions as the main cause for the distortions of the benzene rings in compounds of type 1 and 2.
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    Photolysis of Tetraalkyl-1-pyrazoline-4-thiones. - Diastereoselective Formation of (E)/(Z)-Alkylidenethiiranes from cis- and trans-Tetraalkyl-1-pyrazoline-4-thiones (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1747-1755 
    Details
    ISSN: 0009-2940
    Keywords: 4H-Pyrazole-4-thiones, 3,3,5,5-tetraalkyl-3,5-dihydro ; Thiiranes, 3,3-dialkyl-2-alkylidene ; 1,3-Pentadiene-3-thiol, 2,4-dimethyl ; Photolysis ; Extrusion of molecular nitrogen ; (E)/(Z) Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetraalkyl-1-pyrazolin-4-ones 5 react with hydrazine to afford the hydrazones 6 which are transformed into the thiones 7 in high yields by treatment with disulphur dichloride in the presence of triethylamine. Selective excitation of the azo chromophor of 7a with 350-nm light gives rise to the isopropylidenethiirane 8, besides molecular nitrogen, in a very clean reaction; at almost quantitative conversions, less than 2% of byproducts are observed, and about 10% of 8 have isomerized to the pentadienethiol 9. Photolysis of the stereoisomers cis- and trans-7b yields mixtures of the alkylidenethiiranes (E)-and (Z)-10 with (E)/(Z) ratios of 35:65 and 49:51. The results are interpreted in terms of diastereomeric bis-orthogonal (cis- and trans-21) and mono-orthogonal thioxyallyl diradicals (E)- and (Z)-23 which cyclize to furnish (E)- and (Z)-10. There seems to be a qualitative resemblance between the photochemical and thermal stabilities in the series of 4-substituted tetramethyl-1-pyrazolines, viz. 7a 〈 12 〈 5a, 13, similar to that suggested by Engel for 2,3-diazabicyclo[2.2.2]oct-2-ene derivatives.
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    Funktionalisierte OctabisvaleneHerrn Professor Michael Hanack zum 60. Geburtstag gewidmet. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1757-1775 
    Details
    ISSN: 0009-2940
    Keywords: Octabisvalene, 3-, 2,3-, and (Z)-3,7-(di)functionalized derivatives ; NMR Analysis, 13C,13C coupling constants ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalized OctabisvalenesQuadricyclanone (13) is the starting material for a five-step synthesis of 3-cyanooctabisvalene (24, 19% total yield), cyclooctatetraene for a six-step synthesis of (Z)-3,7-dicyanooctabisvalene (58, 7% total yield). By decyanation of 24, the parent octabisvalene (1) is produced. NMR data, including 13C,13C coupling constants, are presented.
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    Organische Synthesen mit übergangsmetall-Komplexen, 52 N-Vinylaminocarben- und N-(2-Propenyl)aminocarben-Komplexe durch Addition von Keteniminen an Carben-Eisenkomplexe (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1795-1803 
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    ISSN: 0009-2940
    Keywords: Aminocarbene complexes of iron ; N-Vinylaminocarbene complexes ; π-Allyl,σ-complexes of iron ; N-(2-Propenyl)aminocarbene complexes ; Methylenation of ketene imines by carbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses with Transition Metal Complexes, 52 1). - N-Vinylaminocarbene and N-(2-Propenyl)aminocarbene Complexes by Addition of Ketene Imines to Carbene Iron ComplexesKetene imines R(Me)C = C = NPh (2, R = Me, Et, i-Pr) form 1 : 1 adducts with the carbene iron complex (CO)4,Fe=C(OEt)Ph (1). The initial step of the reaction involves an attack of the nitrogen atom of 2 at the carbene carbon atom of 1 and a subsequent rearrangement to give N-vinylaminocarbene complexes (E/Z)-4. In a parallel process with different regiochemistry the central carbon of the CCN unit is attached to the carbene carbon to yield π-allyl,σ-complexes (E/Z)-3. Alkylation of 3a with [Et3O]BF4 leads to the formation of a cationic N-(2-propenyl)-aminocarbene complex 6a. Protonation of 4 with trifluoroacetic acid results in a ring contraction to give the four-membered metallacycles 7. X-ray data are reported for prototypes (Z)-4c and 6a.
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    Structures of Tris(donor)-Tris(acceptor)-Substituted Benzenes, 1. Steric, Polar and Hydrogen-Bonding Effects in TriaminotrinitrobenzenesDedicated to Professor Horst Prinzbach on the occasion of his 60th birthday. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1719-1725 
    Details
    ISSN: 0009-2940
    Keywords: Conformational analysis ; “Push-pull” interaction ; Benzene ring, deformation to boat and twist-boat forms ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray analyses of three 1,3,5-tris(alkylamino)-2,4,6-trinitrobenzenes (alkyl = iPr, neopentyl, tBu; 1d - f) show their benzene rings to be highly distorted towards boat (1d iPrNH2) and twist-boat (1e,f) forms. The patterns found for intramolecular donor-acceptor interaction and hydrogen bonding depend on the conformation of the benzene core: boat structures have the “stern” amino group strongly donating to the “bow” nitro group in the para position and two stronger hydrogen bonds between the substituents on the “side” of the boat, whereas twist-boat structures have two amino groups strongly interacting with the nitro group in their common ortho position to which there are also two strong hydrogen bonds. 1d - f undergo conformational exchange on the 13C-NMR time scale at room temperature. Cooling to 220 K allows detection of all carbon signals and shows C1 symmetry to be present. AM1 calculations reproduce the distortions of 1d - f. Computations on several 2,4,6-tridonor-substituted 1,3,5-trinitrobenzenes indicate that the pronounced deviations from planarity in 1a - f originate largely from electronic effects.
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    Stable N-Phosphanyl Nitrilimines: Reactivity on the Periphery of the Nitrilimine Skeleton (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1739-1746 
    Details
    ISSN: 0009-2940
    Keywords: Nitrilimines ; Phosphorus heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions involving the λ3-phosphorus atom of N-[bis(diisopropylamino)phosphanyl)]-C-[(bis(diisopropylamino) -thio-phosphoranyl)nitrilimine (1) are reported. Addition of elemental sulfur or selenium to 1 leads, by a formal [1 + 4] cycloaddition, to 1,3,4,2λ5-thiadiazaphosphole 3a or 1,3,4,2λ5-selenodiazaphosphole 3b in 85 and 84% yield, respectively. Reactions of 1 with dimethyl acetylenedicarboxylate and tetracyanoethylene afford the corresponding [2 + 4] adducts 1,2,3λ5-diazaphosphinine 6 (80% yield) and 1,2,4,3λ5-triazaphosphinine 10 (80% yield). Phenyl azide reacts with 1 with loss of nitrogen to give 1,2,4,3λ5-triazaphosphole 15 (74% yield), while the reaction of 1 with α-diazo ketone 17 leads with conservation of the N2 grouping to the formation of 1,2,4,3λ5-triazaphosphole 20 (85% yield). Addition of methyl trifluoromethanesulfonate to 1 affords N-[bis(diisopropylamino)methylphosphonioyl]-C-[bis(diisopropylamino)thiophosphoranyl]nitrilimine 22. In contrast to 1, the new stable nitrilimine 22 is strongly electrophilic. [2 + 3] cycloadditions are observed with ethyl vinyl ether, styrene, methyl acrylate and phenylacetylene to furnish the corresponding pyrazolines 23 - 25 and pyrazole 26 in good yields. Water adds to 22 by a 1,3-addition process to give hydrazine 27 (88% yield). The lithium salt 30 of [bis(diisopropyl-amino)thiophosphoranyl](diazo)methane reacts with [bis(pentafluorophenyl)](chloro)phosphane to afford the corresponding diazo compound 32 (50% yield) while the reaction with (chloro)(phenyl)[2,4,6-tris(trifluoromethyl)phenyl]phosphane furnishes nitrilimine 33 in 82% yield. Only 1,3-addition reactions with water or diisopropylamine leading to hydrazine 34 (65% yield) and hydrazone 35 (54% yield) are observed on treatment with this new poorly reactive nitrilimine.
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    3-Aza- und syn-3,7-Diazaoctabisvalen Synthesen, Röntgenstrukturanalysen, neue HeterocyclenHerrn Professor Kurt Schaffner zum 60. Geburtstag gewidmet. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1777-1794 
    Details
    ISSN: 0009-2940
    Keywords: Azaoctabisvalenes ; Heterocycles, novel ; Carbonitriles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Aza- and syn-3,7-Diazaoctabisvalene. - Syntheses, X-ray Structural Analyses, Novel HeterocyclesPreparatively useful routes for 3-aza- and syn-3,7-diazaoctabisvalenes have been designed based on well available materials. Thus, 7-cyano-3-azaoctabisvalene (4) becomes available in a six- (five-) step synthesis from the valence tautomers 7-cyanotropilidene ⇄ 7-cyanonorcaradiene (7 ⇄ 8) (derived dioxides 9/10) in an overall yield of ca. 30%, syn-3,7-diazaoctabisvalene (5) in a three-step synthesis from muco-diazidotetrol 30a in ca. 25% overall yield. For 4 and 5 spectroscopic (e.g. 15N-NMR resonances, 13C,13C coupling constants) and structural details (X-ray analyses) are determined. 4 and 5 serve as starting materials for the construction of several novel heteropolycyclic skeletons (e.g. 46, 48, 50, 51, 52, 54).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240815
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    Zur Alkylierung von 1,3-Dithietan-1,1,3,3-tetroxid (Disulfen) mit Nonafluorbutansulfonsäureestern (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1805-1807 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Dithietane 1,1,3,3-tetroxides, substituted ; Nonafluorobutanesulfonates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of 1,3-Dithietane 1,1,3,3-Tetroxide (Disulfene) by NonafluorobutanesulfonatesSilyl and alkyl esters of nonafluorobutanesulfonic aicd are extremely powerful substitution reagents for disulfenes. Starting from trans-2,4-trimethylsilyldisulfene (1) and methyl nonafluorobutanesulfonate (11), 2,4-dimethyl-2,4-bis(trimethylsilyl)-1,3-dithietane 1,1,3,3-tetroxide (2) is prepared. 2 is hydrolyzed to 2,4-dimethyl-1,3-dithietane 1,1,3,3-tetroxide (3). Rapid H/D exchange reaction of 3 with D2O leads to 4. Compound 3 is deprotonated by aqueous potassium hydroxide and a potassium salt is obtained, the structure of which is most probably 5a. 2,2,4,4-Tetramethyl-1,3-dithietane 1,1,3,3-tetroxide (7) is obtained from 5 and methyl iodide, i.e. the ring system remains intact, whereas hydrolysis furnishes the ring-opened product 6.  -  Three new routes for the synthesis of methyl nonafluorobutanesulfonate (11) via the silver salt 9 or dimethyl sulfate (96% yield) or nonafluorobutanesulfonic anhydride (10) are described.
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    URL: http://dx.doi.org/10.1002/cber.19911240817
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  • 188
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    Photo Valence Isomerization of 8,9-Bis(N-cyclohexylcarbamoyloxymethyl)-[6]paracyclophane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1831-1835 
    Details
    ISSN: 0009-2940
    Keywords: [6]Paracyclophanes ; Dewar isomers ; Prismane isomers ; Photo valence isomerization ; Quantum yields ; Activation energy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation in the wavelength range of λ = 270 - 320 nm of 8,9-bis(N-cyclohexylcarbamoyloxymethyl)-[6]paracyclophane(1b) in dilute fluid solutions produces the 1,4-Dewar isomer 2b in a quantum yield of 2.8% while the quantum yield of the rearomatization is 19% in heptane at room temperature. A photostationary equilibrium may be attained which depends strongly on the wavelength of irradiation. At λ = 290 nm 76% of the [6]paracyclophane isomer 1b is obtained whereas at λ = 310 nm 83% of the Dewar isomer 2b is formed in ethanol. The thermal back reaction 2b → 1b follows the Arrhenius law (Ea = 95.9 ± 4.0 kJ/mol, lg A = 10.6 ± 0.4 in heptane). By irradiating 1b with λ 〈 270 nm the prismane isomer 3b is formed via the Dewar isomer 2b.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240821
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  • 189
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    Notizen/Notes Kronenether aus o-Chinondiaziden und Oxetan (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1865-1866 
    Details
    ISSN: 0009-2940
    Keywords: Carbonyl carbenes ; Oxygen ylides ; Displacement, nucleophilic, intramolecular ; Carbenes ; Ylides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crown Ethers from o-Quinone Diazides and OxetaneThe carbenes 11, generated by photolysis of the di- and tetrachloro-o-quinone diazides 10, react with oxetane in a 1:3 ratio to give the 15-membered crown ethers 19. In the presence of methanol, the oxonium ions 12 are trapped with formation of 1-(aryloxy)-3-methoxypropanes (13). In the absence of additional nucleophiles, 12 reacts with oxetane until the chain length is appropriate for inverting intramolecular attack of the aryl oxide at the α-carbon atom of the oxonium ion (18 → 19).
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240825
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  • 190
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    Reaktionen vinyloger Oxycarbene mit Methanol (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1867-1869 
    Details
    ISSN: 0009-2940
    Keywords: Carbenes, nucleophilic ; Cyclohexadienylidenes ; Pyrylium ions ; Carboxonium ions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Vinylogous Oxycarbenes with MethanolThe carbenes 16 and 30 were generated in methanol/sodium methoxide by photolyses of 2-methylchromone tosylhydrazone (14) and 3,5-dimethoxy-4,4-dimethyl-2,5-cyclohexadienone tosylhydrazone (28), respectively. Neither 16 nor 30 accept methanol at the carbenic site to give products of a formal O - H insertion. Carbene 16 affords 2-methoxy-2-methyl-2H-1-benzopyran (19) by way of the benzopyrylium ion 17. The same ether was obtained from the independently prepared perchlorate of 17. Protonation of 30 was followed by demethylation of the delocalized carboxonium ion 31 to give 5-methoxy-6,6-dimethyl-2,4-cyclohexadienone (33) as the only product.
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    URL: http://dx.doi.org/10.1002/cber.19911240826
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  • 191
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    Zur Chemie von Haftgruppen, VI über die Eignung verschiedener Aldehyde und Ketone als Haftgruppen für Monoalkohole (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1885-1885 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240831
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  • 192
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    The 2,4-Bis(diphenylmethylene)-1,3-cyclobutane-dione Diradical Dianion and Its Sulphur Analogues (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1885-1885 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240832
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  • 193
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    Zweifache Borylierung von Benzolderivaten mit (Diisoalkylamino)boradiyl-Einheiten (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1907-1912 
    Details
    ISSN: 0009-2940
    Keywords: (Diisoalkylamino)boradiylbenzene derivatives ; Borolo[3,2-b]borole ; 2,8-Diborabicyclo[3.2.1]octa-3,6-diene ; Borylation of benzene derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twofold Borylation of Benzene Derivatives with (Diisoalkylamino)boradiyl UnitsThe reaction of subvalent boron species generated by the defluorination of difluoro(diorganylamino)borane with Na/K alloy in the presence of 1,4-disubstituted benzene derivatives leads to products which contain two (diorganylamino)boradiyl units and two remaining double bonds which are located on the substituted C atoms. Compounds 5 to 8 exhibit structures based on a 2,8-diborabicyclo[3,2,1]octa-3,6-diene skeleton while 9 shows a skeleton with a 1,3a,4,6a-tetrahydroborolo[3,2-b]borole structure. The latter structure corresponds to that of 1 obtained in the same reaction with benzene. The compounds are characterized by elemental analyses and spectroscopically [MS, NMR (1H, 11B, 13C, 15N, 19F, 29Si)]. X-ray structure analyses are presented for 1, 6, 7, 8, and 9.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240904
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    Eine einfache Synthese von 1,3-Diphospha-2,4-disilabicyclo[1.1.0]butanen und Isomerisierung durch Silicium-Inversion (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1923-1929 
    Details
    ISSN: 0009-2940
    Keywords: 1,3,2,4-Diphosphadisiletanes, 1,3-bis(tert-butylmercurio)-substituted ; Mercury - phosphorus bond ; 1,3-Diphospha-2,4-disilabicyclo[1.1.0]butanes ; Silicon inversion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Facile Synthesis of 1,3-Diphospha-2,4-disilabicyclo[1.1.0]butanes and Isomerization by Silicon InversionDilithiation of the PH positions of the P2Si2 cyclobutanes 2a - h with n-BuLi and treatment with tBuHgCl leads to the 1,3-bis(tert-butylmercurio) compounds 3a - h. According to NMR spectroscopy and X-ray structural analysis the tert-butylmercurio groups at phosphours occupy trans configuration. Photolysis of solutions of 3a - d and 3f, g in toluene yields the corresponding 1,3-diphospha-2,4-disilabicyclo[1.1.0]butanes 1a - d and 1f, g. Interestingly, the dimercury compound 3e (R = mesityl and tert-butoxy) is quite stable in visible light, probably due to intramolecular donor (tBuO) acceptor (Hg) stabilization. Starting from 3b, the light-induced elimination of the tBuHg groups gives the expected exo,endo-P2Si2-bicyclo[1.1.0]butane 1b only as intermediate. The final product of the latter photolysis is the CMe3/CMe3-exo,exo isomer 1b′. The formation of 1b′ from 1b is an irreversible silicon inversion process caused by unfavourable interaction of the endo substituents in 1b. In comparison, the exo,endo isomer of 1g (R = isityl and CMe3 at silicon) does not rearrange to the Me3C/Me3C-exo,exo derivative 1g′ under similar photolysis conditions or when heated at 140°C for several days. The route to 1,3-diphospha-2,4-disilabicyclo[1.1.0]butanes 1 described herein allows the synthesis of new derivatives which cannot be prepared from disilenes and white phosphorus.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240907
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    Anticancer Agents, 17. 1,4-Disila[6]radialene: Aktivierungsparameter der Sessel-Twist-Inversion und analytische Enantiomerentrennung der Twist-Konformeren (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2019-2024 
    Details
    ISSN: 0009-2940
    Keywords: Antitumor agents ; Antiviral agents ; Acyclonucleosides ; Pyrimidines ; Acetales ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2,4-bis-O-trimethylsilyluracil (2) and 5-fluoro-2,4-bis-O-trimethylsilyluracil (3), respectively, with acetals 4a - m of various aliphatic and aromatic aldehydes in the presence of trimethylsilyl trifluoromethanesulfonate (5) at - 30°C gives the 1-(1'-alkoxyalkyl)- and 1-(1'-alkoxy-1'-phenylmethyl)-pyrimidines 6a - m and the corresponding 5-fluorouracil derivatives 7a - f in 40 - 91% yield.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240923
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    1,3-Cyclopentandiyle - Intermediate oder Übergangszustände? (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2041-2046 
    Details
    ISSN: 0009-2940
    Keywords: 1,3-Diradicals, energy well, singlet-triplet splitting ; 1,3-Cyclopentanediyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Cyclopentanediyls - Intermediates or Transition States?The energy well of the singlet diradicals 4a and 6 has been determined by the oxygen trapping technique to be 2.7 and 1.9 kcal/mol, respectively. From the oxygen and temperature dependence of the trapping rate of the diradical 4a activation barriers of 2.2 and 4.9 kcal/mol have been derived for the mutual interconversion of the spin isomers with the triplet being the ground state.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240927
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  • 197
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    Notizen/Notes Synthese und Struktur von 2-Phosphonioallen-Komplexen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1973-1976 
    Details
    ISSN: 0009-2940
    Keywords: 2-Phosphonioallene ligands ; Metallobis(methylene)phosphoranes ; Nickel complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of 2-Phosphonioallene ComplexesThe reaction of the chlorobis(methylene)phosphorane 1 with reactive olefin complexes of nickel and platinium affords the 2-phosphonioallene complexes 4b and 6a,b. The structure of this new class of three-electron donor ligands, involving a lowcoordinated phosphorus (V) cation, has been elucidated by NMR spectroscopy and a single-crystal X-ray study of 6a. The reaction proceeds via a metallobis(methylene)phosphorane intermediate, which could be isolated in the case of the (Et3P)2Pt complex 3a.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240914
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    Tin for Organic Synthesis, 4 Mild and Efficient Synthesis of Aromatic Sulfonamides by in situ Preparation of the Corresponding Sulfonyl Isocyanates (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1997-2000 
    Details
    ISSN: 0009-2940
    Keywords: Electrophilic aromatic substitution ; Sulfodestannylation ; Isocyanates, sulfonyl, aromatic ; Sulfonyl compounds ; Trialkylarylstannanes, application of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240919
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    Mehrstufige reversible Redoxsysteme, LVI. Kristallstruktur und Leitfähigkeiten der CT-Komplexe TTF/2-X-5-Me-DCNQI (X = Cl, Br, I) aus Tetrathiafulvalen und 2-Halogen-N,N′-dicyan-5-methyl-1,4-benzochinondiimin (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2005-2011 
    Details
    ISSN: 0009-2940
    Keywords: Charge-transfer complexes ; Conductivity ; Redox systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LVI. - Crystal Structures and Conductivities of the CT Complexes TTF/2-X-5-Me-DCNQI (X = Cl, Br, I) from Tetrathiafulvalene and 2-Halogeno-N,N′-dicyano-5-methyl-1,4-benzoquinone DiimineIn contrast to microcrystalline powders single crystals of the title complexes show low conductivities (&10; 〈 sigma-5 Scm-1). These properties are based on a peculiar mixed stack arrangement of donor and acceptor molecules within the crystal lattice (space group P21/n).
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240921
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    Kohlenwasserstoffverbrückte Komplexe XX Nucleophile Addition von Carbonylmetallaten an kationische Hexadienyl-, Cycloheptadienyl-, Cycloheptadienyl- und Cyclooctadienyl-Komplexe von Eisen und Ruthenium: Heterodimetall-Komplexe mit η1:η4-C6-, -C7- und -C8-Kohlenwasserstoffbrücken (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2227-2236 
    Details
    ISSN: 0009-2940
    Keywords: Heterobimetallic complexes ; Tungsten complexes ; Iron complexes ; Ruthenium complexes ; Manganese complexes ; Rhenium complexes ; Diene bridges, σ,π-C6, -C7, and -C8 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal Complexes, XX. - Nucleophilic Addition of Carbonyl Metallates to Cationic Hexadienyl, Cyclohexadienyl, Cycloheptadienyl, and Cyclooctadienyl Complexes of Iron and Ruthium: Heterobimetallic Complexes with η1:η4, -C6, -C7, and -C8 Hydrocarbon BridgesThe addition of Re(CO)-5, Mn(CO)-5, and [(η5-C5H5)W(CO)3]- to the cationic dienyl complexes [(η5-dienyl)M(CO)3]+ (M = Fe, Ru; dienyl = hexadienyl, cyclohexadienyl, cycloheptadienyl, cyclooctadienyl, bicyclo[5.1.0]octadienyl) gives the heterobimetallic η1:η4-hydrocarbon-bridged complexes 1 - 4, 6, 7. In solution the initial nucleophilic adduct 2e of [(η5-cyclo-hexadienyl)Ru(CO)3]+ and [Re(CO)5]- rearranges to the complex 3, in which the Re(CO)5 group is bound to a sp2 carbon atom. By using Mn(CO)-5 also the products of electron transfer between cation and anion have been observed. The crystal structures of (OC)3Fe(μ-η4:η1-hexadiene)Re(CO)5 (1), (OC)3Ru(μ-η4:η1-cyclohexadiene)Re(CO)5(3), (OC)3Fe(η4:η4-C7H9 - C7H9)Fe(CO)3 (5), (OC)3Ru(μ-η4:η1-cyclooctadiene)Re-(CO)5 (6b), and of (OC)3Fe(η4:η1-bicyclo[5.1.0]octadiene)-Re(CO)5 (7) have been determined by X-ray diffraction.
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    URL: http://dx.doi.org/10.1002/cber.19911241014
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