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  • Inorganic Chemistry  (7,724)
  • Magnetism  (3,545)
  • EARTH RESOURCES AND REMOTE SENSING
  • 2010-2014  (3,542)
  • 1990-1994  (4,883)
  • 1925-1929
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  • 101
    Electronic Resource
    Electronic Resource
    Darstellung aromatischer Fluor-Verbindungen durch nucleophilen Austausch von Nitro-Gruppen gegen Fluorid (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 157-162 
    Details
    ISSN: 0009-2940
    Keywords: Fluoro compounds, aromatic ; Nitrite exchange by fluoride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Aromatic Fluoro Compounds by Nucleophilic Exchange of Nitro Groups by FluorideThe synthesis of aromatic fluoro compounds from the respective nitro compounds by nucleophilic substitution of nitrite by fluoride is described. Reasonable yields in case of nonactivated nitro compounds are only obtained if the nitrite formed in the reaction is eliminated by acylation. 1-Fluoro-3-nitrobenzene (2) was obtained from 1,3-dinitrobenzene (1), and 1-fluoro-3,5-dinitrobenzene (9) as well as 1,3-difluoro-5-nitrobenzene (10) from 1,3,5-trinitrobenzene (8) in yields up to 92% by reaction of nitro compounds with potassium fluoride in sulfolane at 180 - 200°C in the presence of phthaloyl dichloride (6); 1,2-difluoro-4-nitrobenzene (12) was formed in 58% yield from 2,4-dinitro-1-fluorobenzene (11) in the presence of pyromellitoyl tetrachloride (13).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240124
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  • 102
    Electronic Resource
    Electronic Resource
    Inversionsbarrieren Ortho,ortho′-verbrückter Biphenyle (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2349-2371 
    Details
    ISSN: 0009-2940
    Keywords: Atropisomers ; Inversion barrier ; Lineshape analysis ; Calculations, force field ; Resonance energy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Inversion Barriers of ortho,ortho′-Bridged BiphenylsThe syntheses and spectroscopic properties of the ortho,ortho′-bridged biphenyls 2-19 are described. In the case of 5, 15, and 16 the inversion barrier is determined from the temperature dependence of the NMR spectra (lineshape analysis), in the case of 12, 13, and 14 from the temperature of coalescence, and in the case of 2a, 3b, 7, 17, 18, and 19 from the rate of racemization of the optically active compounds. The experimental inversion barriers, including data from the literature, are compared with those calculated using the extended force field (MM2erw). The conformational behavior of the title systems is significantly affected upon transformation into the corresponding dianion salts. The relevant energy terms are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231219
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  • 103
    Electronic Resource
    Electronic Resource
    On the mechanism of diels-alder reactions of nitroso alkenes: exo/endo selectivity, stereospecificity, E/Z selectivity, and relative reactivity of various olefins (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2403-2411 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Oxazines ; Hetero Diels-Alder reactions ; Nitroso alkene cycloaddition ; exo: endo Selectivity ; Stereospecificity ; Silyl enol ethers, relative reactivity of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the hetero Diels-Alder reaction of nitroso alkenes 2 with silyl enol ethers and other olefins has been investigated. Using the bicyclic nitroso compound 2a a study of the exo/endo selectivity has demonstrated that the exo approach is preferred with the siloxyethene l a as dienophile. On the other hand, the siloxycyclopentene 1 c gives a mixture of cycloadducts 3 c with an excess of endo product (endo: exo = 82: 18). The stereospecificity of the nitroso alkene cycloaddition could be demonstrated with the stereochemically homogeneous silyl enol ethers 1 b and 1 d. Experiments with enol ethers 1 f and 1 g also occur stereospecifically. α-Nitrosostyrene 2b reveals surprisingly high kE/Z values when E/Z-isomeric olefins are compared in competition experiments. Also, a detailed reactivity scale of 2b including various structurally different silyl enol ethers and other typical dienophiles shows that a complex interplay of electronic and steric effects is operating. The large influence of steric effects is taken as evidence for a highly ordered transition state in the cycloaddition. All mechanistic details for the Diels-Alder reactions of nitroso alkenes 2 with (silyl) enol ethers are in strong accord with a concerted mechanism and exclude the involvement of zwitterions or diradicals as intermediates.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231224
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  • 104
    Electronic Resource
    Electronic Resource
    Macrocyclic pyridinophanetetraene (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2445-2447 
    Details
    ISSN: 0009-2940
    Keywords: Key Words: Cyclophane ; Pyridinophane ; Polyene ; Macrocycle ; Kharash coupling reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new pyridinophanetetraene 4 has been prepared in a two-step synthesis by a modified Kharash coupling reaction of 2,6-bis[3-lithio-(E)-styryl]pyridine with copper(II) chloride. Starting from isomerically pure 2,6-bis[3-bromo-(E)-styryl]pyridine (3), the cyclization reaction takes place without rearrangement of the stilbazole double bonds. The electronic spectrum of 4 shows characteristic differences when compared to that of its open-chain analogue 2,6-bis[(E)-styryl]pyridine (7).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231228
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  • 105
    Electronic Resource
    Electronic Resource
    [1.1.1]Propellane and maleic anhydride: Face-specific copolymerization with formation of an alternating 1:1 copolymer (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2449-2451 
    Details
    ISSN: 0009-2940
    Keywords: Key Words: [1.1.1]Propellane, copolymer with maleic anhydride ; Maleic anhydride, copolymer with [l.l.l]propellane ; Copolymerization, spontaneous ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spontaneous and face-specific copolymerization of [l.l.l]propellane and maleic anhydride to give the strictly alternating 1:1 copolymer 2 is described. The molecular weight of 2 after transformation into the corresponding diester 5c was determined to be 80.000 (Mn) and 220.000 (Mw), respectively.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231229
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  • 106
    Electronic Resource
    Electronic Resource
    Direkte Michael-artige Addition von Si-Gruppen an β-Aryl-α,β-ungesättigte Carbonylverbindungen mit R3SiCl/Bu2Cu(CN)Li2 (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2439-2444 
    Details
    ISSN: 0009-2940
    Keywords: Michael addition of Si groups ; Cuprates, higher-order ; Ketones, β-aryl β-silyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct Michael-Type Addition of Si-Groups to α,β-Unsaturated p-Aryl-Substituted Enones with R3SiCl/Bu2Cu(CN)Li2(E)-5-Benzylidene-2-tert-butyl-6-methyl-1,3-dioxan-4-one (1) undergoes conjugative silylation (Me3Si, Et3Si, tBuMe2Si, Me2PhSi, products 2 - 5) with the reagent specified in the title. The reaction is highly diastereoselective, with formal anti addition of R3Si and H from the Re- and Si-face, respectively, of the exocyclic double bond [proof by NMR analysis and chemical correlation (cf. 6 and 7). A screening of various enone systems showed that this unprecedented Michael addition of Si groups with chlorosilane as a reagent, and under non-reducing conditions occurs only if the x,p-unsaturated carbonyl system bears an aryl group in the P-position to give β-aryl β-silyl ketones (products 8- 15).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231227
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  • 107
    Electronic Resource
    Electronic Resource
    Cyclization of a chiral α-(δ′-benzyloxyalkyl)acrylate to a novel tetrahydrofuran derivative (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2455-2456 
    Details
    ISSN: 0009-2940
    Keywords: Tetrahydrofurans ; Acrylates, α-(δ′-hydroxyalkyl)- ; Aldehydes, β-hydroxy- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 3-hydroxy-2-(iodomethyl)-5-methyltetrahydrofuran-2-carboxylate (4) is synthesized from (3S)-3-(benzyloxy)butanal (2) via methyl 5-(benzyloxy)-3-hydroxy-2-methylenehexanoate (3a) as intermediate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231231
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  • 108
    Electronic Resource
    Electronic Resource
    Synthese und Struktur von Bis[bis(diisopropylamino)phosphino]chalkogeniden (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 13-16 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphines, tetrakis(diisopropylamino) ; Phosphinous anhydrides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Bis[bis(diisopropylamino)phosphino]chalcogenidesPhosphorodiamidous chalcogeno-anhydrides [(R2N)2P]2X (R = Me2CH; X = S, Se, Te) (2a-c) have been obtained by insertion of elemental sulfur, selenium, or tellurium into the P-P bond of the corresponding diphosphane (1). The structure of 2a and 2c has been confirmed by an X-ray diffraction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240103
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  • 109
    Electronic Resource
    Electronic Resource
    (Perfluoralkyl)(dimethylamino)sulfonium-hexafluoroarsenate (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 31-38 
    Details
    ISSN: 0009-2940
    Keywords: Fluorosulfonium salts, reaction with nucleophiles ; (Perfluoroakyl)(dimethylamino)sulfonium salts, preparation and structures of ; Methoxysulfinyl hexafluoroarsenate, alkylation with ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Perfluoroalkyl)(dimethylamino)sulfonium HexafluoroarsenatesMeN = S(CF3)2 (5) is alkylated by Me3O⊕ AsF⊖6 to Me2N-S(CF3)⊕2 AsF⊖6 (4). From 5 and MeOSO⊕ AsF⊖6 (6) MeOS(O)-N(Me)S(CF3)⊕2 AsF⊖6 (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur-bonded fluorine in CF3SF⊕2 AsF⊖6 (8) by Me3SiNMe2 yields CF3S(NMe2)⊕2 AsF⊖6 (9). Similarly, (CF3)2CFSF⊕2 AsF⊖6 (10) reacts with dimethyl(trimethylsilyl)amine to give (CF3)2CFS(NMe2)⊕2 AsF⊖6 (11). The structures of 4 and 9 are elucidated by X-ray analyses, and the influence of the substituents on the bonding is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240106
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  • 110
    Electronic Resource
    Electronic Resource
    Übergangsmetall-Silyl-Komplexe, 36 Zur Frage von Gold-Gold-Wechselwirkungen bei Ph2P[CH2]1(2) PPh2 verbrückten zweikernigen Gold-Silyl-Komplexen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 63-67 
    Details
    ISSN: 0009-2940
    Keywords: Dinuclear gold complex ; Silyl complex ; Gold-gold interaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Silyl Complexes, 361).  -  On the Question of Gold-Gold Interactions in Ph2P[CH2]t(2)PPh2-Bridged Dinuclear Gold Silyl ComplexesDinuclear silyl gold complexes of the type dppm(AuSiR3)2 (1) or dppe(AuSiR3)2 (2) are prepared by the reaction of dppm-(AuCl)2 or dppe(AuCl)2 with two equivalents of LiSi(aryl)3 or LiSi(SiMe3)3 The complex dppe[AuSi(SiMe3)3]2 (2 c) exhibits crystallographic inversion symmetry, and therefore the distance between both gold atoms is a maximum. In dppm-(AuSiPh3)2 (1b) a gold-gold interaction between both gold atoms is observed [Au  -  Au 316.80(3) pm].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240110
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  • 111
    Electronic Resource
    Electronic Resource
    Cyclobuten-Ringöffnung: Eine nützliche Reaktion zur Synthese doppelsträngiger Moleküle (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 149-156 
    Details
    ISSN: 0009-2940
    Keywords: Cyclobutene, ring-opening ; Poly Diels-Alder reaction ; Molecules, double-stranded ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclobutene Ring Opening: A Useful Reaction for the Synthesis of Double-Stranded MoleculesSyntheses and ring-opening reactions of the compounds endo-5a - e and 9a - c, all containing cyclobutene rings, are described. From these experiments it is concluded that compound 9a is a useful AB-type Diels-Alder monomer for the synthesis of well-defined double-stranded molecules. The stereochemistry of the adducts endo-4b and endo-5d is determined by X-ray structure analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240123
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  • 112
    Electronic Resource
    Electronic Resource
    Zur Reaktion von Dialkylphosphiten mit α-Enonen, I Synthese und Allyl-Umlagerung von (1-Hydroxy-2-alkenyl)- und (1-Hydroxy-2-cycloalkenyl)phosphonsäure-dimethylestern (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 175-184 
    Details
    ISSN: 0009-2940
    Keywords: α-Enones, regioselective 1,2-addition of dimethyl phosphite to ; Allylic rearrangement of dialkyl (1-hydroxy-2-alkenyl)phosphonates ; 1-Alkenylphosphonates, 3-acetyloxy- ; 1-Alkenylphosphonates, 3-hydroxy- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Dialkyl Phosphites with α-Enones, I. - Synthesis and Allylic Rearrangement of Dimethyl (1-Hydroxy-2-alkenyl)- and (1-Hydroxy-2-cycloalkenyl)phosphonatesVarious β,γ-unsaturated α-hydroxyphosphonates 3 are prepared in good yields by NaOCH3-catalyzed regioselective 1,2-addition of dimethyl phosphite to acyclic and cyclic α-enones at -35°C. On acid-catalyzed acetylation, the allylic α-hydroxyphosphonates 3 (R1, R2 + H) rearrange under thermodynamic control; yielding the new 3-acetyloxy-1-(cyclo)alkenyl derivatives 8, from which the transposed allylic alcohols 11 are readily obtained. Using shorter reaction times, acetylation of compounds 3 affords mixtures of 1- and 3-acetylated products, 10 and 8, respectively.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240126
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  • 113
    Electronic Resource
    Electronic Resource
    Trioxypentafulvenes, 2 synthesis of 1-substituted 2,3,6-trioxypentafulvenes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 207-212 
    Details
    ISSN: 0009-2940
    Keywords: 2,3,6-Trioxypentafulvenes ; Keto-enol tautomerism ; Push-pull system ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses of 2,3,6-trioxypentafulvenes with a free position at the ring are described, in which the protection of the C-3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4-disubstituted 2,3,6-trihydroxypentafulvenes 2a-e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push-pull system formed by the C-3 enol group and the C-4 electron-withdrawing substituent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240131
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  • 114
    Electronic Resource
    Electronic Resource
    Neue O6-Makrocyclen mit 2,2-Bis(2-furyl)propan-Einheiten (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 233-235 
    Details
    ISSN: 0009-2940
    Keywords: Hexaoxacyclotriacontadodecaenes ; Macrocycles ; 2,2-Bis(2-furyl)propane ; 2,5-Bis[1-(2-furyl)-1-methylethyl]furan ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New O6 Macrocycles with 2,2-Bis(2-furyl)propane UnitsThe macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2-bis(2-furyl)propane (1) and 2,5-bis[1-(2-furyl) 1-methylethyl]furan (5), respectively, with ethyl N,N-dimethylcarbamate (2).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240135
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  • 115
    Electronic Resource
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    Umlagerungen von 1,4,4- und 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl-Kationen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 237-240 
    Details
    ISSN: 0009-2940
    Keywords: Bicyclo[3.2.1]oct-6-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Conformational effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangements of 1,4,4- and 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl Cations1,4,4-Trimethylbicyclo[3.2.1]oct-6-yl cations (18) are generated from the tosylhydrazone 7, by nitrous acid deamination of the amines 6 and 8, and by acetolysis of the brosylates 21 and 24. The product distributions are but slightly affected by the configuration (exo vs. endo) of the leaving groups. The predominant product, 1,4,4-trimethylbicyclo[3.2.1]octan-exo-6-ol (11) is formed without significant redistribution of a 6-2H label. The degenerate Wagner-Meerwein rearrangement of the parent bicyclo[3.2.1]oct-6-yl cation is virtually eliminated by the presence of two methyl groups at C-4. Enhanced conformational strain, raising the barrier to ring flipping, accounts for these observations. Minor products (12, 13) arise from a 7,6-hydride shift of 18, followed by Wagner-Meerwein rearrangement. When the 2,2,5-trimethylbicyclo[3.2.1]oct-6-yl cation (19) is generated directly from the tosylhydrazone 17, the tertiary alcohol 13 is obtained as the major product. The conformational barrier to Wagner-Meerwein rearrangement is compensated by the incipient stabilization of the tertiary carbocation 20.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240136
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  • 116
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    Notizen/Notes Synthesis of 1-Phenyl-1,2- and 4-Phenyl-1,5-dihydropentalenes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 403-405 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Dihydropentalenes ; 1,5-Dihydropentalenes ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient one-pot synthesis of 3-substituted 1-phenyl-1,2-dihydropentalenes from α,β-unsaturated ketones is described. These compounds can be rearranged to their 1,5-dihydro isomers using different methods such as acid catalysis and vacuum-flash thermolysis or by chromatography on alumina.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240226
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  • 117
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    Electrochemical Investigations on Methylenephosphines and Related Systems (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 417-421 
    Details
    ISSN: 0009-2940
    Keywords: Methylenephosphines ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical investigations on a selection of methylenephosphines 1 and related systems are reported. They are shown to possess an irreversible oxidation and reduction wave. An exception is diaminodiphosphene, which reversibly forms a radical anion. A relative ordering of frontier orbitals is possible, based on the redox properties of these systems.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240302
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  • 118
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    Die Kristallstrukturen von Kalium-, Rubidium- und Cäsium-trifluororthocarbonat mit einer Bemerkung zum Bariumsulfat-Typ1 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 321-327 
    Details
    ISSN: 0009-2940
    Keywords: Trifluororthocarbonates of potassium, rubidium, cesium ; Phase transitions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type1)Crystals of potassium, rubidium, and cesium trifluororthocarbonate (9a, 9b, and 9c) have been grown by Ostwald ripening in CH3CN applying a COF2 pressure of 3 bar. According to X-ray single-crystal structure analysis, 9a, 9b, and 9c belong to the baryte-structure family with an pseudotetrahedral anion being dynamically disordered at room temperature. All of the title compounds undergo a phase transition into a monoclinic, completely ordered low-temperature form, which has been refined for 9c. The C - O bond seems to be shortened by polar interactions. The results obtained with 9a, 9b, and 9c at room temperature indicate that the type of disorder found in 9 might be generally present in baryte-type compounds.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240212
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  • 119
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    Selektivitäten bei Photoadditionen an multifunktionelle Coffein-Derivate (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 339-345 
    Details
    ISSN: 0009-2940
    Keywords: Photoadditions ; Caffeine derivatives ; Calculations, AM1 ; Diradicals ; Propellanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selectivities in Photoadditions with Multifunctional Caffeine DerivativesElectronically excited stilbene (21*), 4,4′-dichlorostilbene (1*), and 4,4′-dimethoxystilbene (18*) are trapped by caffeine derivatives 2, 13, or 22 with variable results. While 1* and 2 react predominantly at the imino double bond (substitutive and fragmentating additions), 1* or 18* and 13 produce mostly propellanes by [2 + 2] photocycloaddition, which hydrolyze or may be hydrolyzed. 21* and the relatively electron-poor compound 22 produce mostly propellanes, which always show a preponderance of the syn-10, anti-11 stereoisomers. These selectivities as well as the competition with reactions at the imino double bonds are rationalized on the basis of diradical mechanisms with the aid of semiempirical AM1 calculations. Earlier results on closely related transformations are also discussed.
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    Addition von Phosphor-Nucleophilen an Benzothiet (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 377-381 
    Details
    ISSN: 0009-2940
    Keywords: Phosphorus compounds, organic ; Phosphorus heterocycles ; Arbuzov rearrangement ; Mechanism, SN2, SN1 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition Reactions of Phosphorus Nucleophiles to BenzothieteTrialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement - related to the Arbuzov reaction - can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 → 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a-d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a - d. An intramolecular rearrangement in a 1:1 adduct is only observed for the 1,3,2-dioxaphosphepine 14e, a benzylic system which allows an SN1 process generating the 1,6,2-oxathiaphosphecine 18e. A similar rearrangement at a tertiary carbon center is prevented by the competitive addition of water (1 + 14f → 20).
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    Dispiro-1,2,4-trioxolane durch Ozonolyse von Cycloalkylidencycloalkanen auf Polyethylen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 391-396 
    Details
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Cycloalkylidenecycloalkanes ; Dispiro-1,2,4-trioxolanes ; Thermolysis ; Photolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dispiro-1,2,4-trioxolanes by Ozonolysis of Cycloalkylidenecycloalkanes on PolyethyleneOzonolyses of symmetrical (1b - d) and of unsymmetrical cycloalkylidenecycloalkanes (8a, b) afforded the dispiro-1,2,4-trioxolanes 4b - d and 9a, b, respectively. Their thermal decompositions gave mixtures of the cyclic ketones (3) and lactones (6). Photolyses afforded in addition to 3 and 6 the cyclic anhydrides 13, which are isomeric with the corresponding dispiro-1,2,4-trioxolanes.
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    Pseudooxokohlenstoff-Anionen der Semidreiecksäure (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 665-669 
    Details
    ISSN: 0009-2940
    Keywords: Semideltic acid ; Cyclopropenylium cations ; Pseudooxocarbon anions ; Semideltate anions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudooxocarbon Anions of Semideltic AcidNovel pseudooxocarbon anions of semideltic acid (2) can easily be obtained by stepwise substitution of the dimethylamino groups of the cyclopropenium perchlorate 8. Treatment of 8 with cyanamide or malononitrile in the presence of triethylamine leads to the triafulvenes 9 and 13. Two cyanoimino groups are successfully introduced into the cyclopropenylium system by treating 9 with excess cyanamide/potassium ethoxide. Under the same conditions malononitrile reacts with 13 to yield the potassium salts 14 and 17. The thioamide 26 of semideltic acid is obtained by treating the triphenylphosphonium salt 24 with H2S/pyridine and subsequent hydrolysis of the intermediate 25. With the anions of cyanamide or malononitrile ring-opening reaction of the cyclopropenylium system of 24 occurs to yield the push-pull phosphonium salts 28 and 29.
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    Darstellung und Kristallstrukturen einiger mit N,N'-Dimethylharnstoff verbrückter Diphosphorverbindungen; NMR-Untersuchung einer λ4P+λ4P+-Diphosphorverbindung (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 35-43 
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    ISSN: 0009-2940
    Keywords: Diphosphorus compounds, mixed valence λ4P+λ4P+, PP-bonded ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Single-Crystal X-ray Structure Investigations of some N,N′-Dimethylurea-Bridged Diphosphorus Compounds: NMR Studies of a λ4P+ λ4P+ -Diphosphorus CompoundThe synthesis of N,N′-dimethylurea-bridged diphosphorus compounds involving the structural elements λ3Pλ4P+ (3b, 3c, and 7) and λ4P+λ4P+ (4 and 8) is described. The salts 4 and 8 were obtained by methylation of the λ3Pλ4P+ compounds 3c and 7 with MeOSO2CF3. The λ3P atom in 3c and 7 coordinates to tungsten(0) with formation of the ionic pentacarbonyl derivatives 9 and 10. The NMR spectra of the diphosphonium salt 4 were completely analyzed using NOE and 2D shift correlation experiments (13C,1H and 31P,1H). The single crystal X-ray structure determinations of 3b and 9 are reported. 3b found to crystallize as a hemisolvate with dichloromethane. The RR/SS diastereomer is present in the crystal. The PP distance amounts to 219.1 pm. Both phosphorus atoms interact weakly with the chloride ion (293, 312 pm). 9 crystallizes as a hemisolvate with toluene, the RS/SR diastereomer being present. A PP distance of 224.7 pm and weak interactions between the phosphorus atoms and an oxygen atom of the anion (305, 308 pm) are found.
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    Beiträge zur Chemie des Bors, 199 Reaktionen eines Amino-imino-borans mit Anilin-Derivaten und Carbonsäureamiden (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 63-65 
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    ISSN: 0009-2940
    Keywords: Acetamides, O,N-diborated / Borane, acetamido(diamino)- / N,O-Borotropy / Borane, anilino(diamino)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Chemistry of Boron, 199. - Reactions of an Amino-imino-borane with Anilines and Carboxylic Acid AmidesThe addition of aniline derivatives to (tert-butylimino)(2,2,6,6-tetramethylpiperidino)borane (1) leading to the mixed triaminoboranes ArNH(Me3CNH)Btmp (2) (tmp = 2,2,6,6-tetramethylpiperidino) is sterically controlled. Reactions of 1 with acetamide produces O,N-diborylated acetimidic acid 4. On the other hand, N-methylacetamide adds 1 to yield the N-borylated N-methylacetamide 5a exclusively. In contrast, N-isopropyl- and N-tert-butylacetamide form also the O-borated isomers (6b, c). Their proportion increases with the steric requirements of the N-substituent of the acetamide derivative.
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    Kohlenwasserstoffverbrückte Metallkomplexe, XVIII. Heterometallische Ethylen-verbrückte Komplexe (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 und (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1059-1063 
    Details
    ISSN: 0009-2940
    Keywords: Ethylene-bridged metal complexes ; Ethanediyl complexes ; Manganese, Rhenium, Ruthenium, Osmium carbonyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-Bridged Metal complexes, XVIII. - Heterometallic Ethylene-Bridged Complexes (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 and (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5Addition of [(OC)5Re(C2H4)]+ to the carbonylmetallates [Mn(CO)5]-, [RuCp(CO)2]-, [Os(CO)4]2-, [Os3(CO)12]2- affords the title complexes in a directed way. The dynamic behaviour of (OC)5ReCH2CH2Mn(CO)5 in solution is attributed to a dyotropic exchange of the pentacarbonylmetal groups on the CH2CH2 bridge.
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    Arsen(III)-, Antimon(III)- und Bismuth(III)-halogenid-Komplexe des [2.2.2]Paracyclophans: Vom lockeren van-der-Waals-Addukt zu stark gerichteten π-Komplexen mit zwei- und dreifacher externer η6-Koordination (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1089-1093 
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    ISSN: 0009-2940
    Keywords: [2.2.2]Paracyclophane ligand ; (η6)π Complexes ; Arsenic(III) complexes ; Antimony(III) complexes ; Bismuth(III) complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arsenic(III), Antimony(III), and Bismuth(III) Trihalide Complexes of [2.2.2]Paracyclophane: From Weak van der Waals Coordination to Strongly Directional π Complexation with Single or Double External η6 Coordination[2.2.2]Paracyclophane forms the adducts C24H24·AsCl3 (1), C24H24·(SbCl3)2·1/2 C6H6 (2), and C24H24·(BiCl3)3·C6H6 (3). For solutions in polar solvents NMR spectra indicate extensive dissociation and/or fluxionality. In the crystals adduct 1 features a weak addition of the AsCl3 molecule to one open side of a paracyclophane molecule with long intermolecular contacts approaching C3v symmetry. - Crystalline 2 shows SbCl3 coordination to two of the benzene rings of the hydrocarbon in a quasi-centered η6 mode, while one of the benzene rings remains uncoordinated. Chlorine-bridging between antimony atoms leads to tetrameric units (SbCI3)4 in the lattice. - In the bismuth compound 3 each benzene ring of the hydrocarbon is engaged in centroid (η6)π complexation, with the BiCl3 units crosslinked by chlorine bridges. The average of the Bi-ring distances (3.08,2.98, and 2.99 Å) is shorter than for the Sb-ring distances in 2 (3.047 and 3.050 Å), indicating stronger bonding. The crystal benzene is not coordinating.
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    Intramolecular, Metallacyclic Organoaluminium, -gallium and -indium Addition Compounds Crystal Structure of 1-Galla-5-azabicyclo[3.3.3]undecane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1113-1119 
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    ISSN: 0009-2940
    Keywords: Metallacyclic organoaluminium, -gallium and -indium compounds ; MOVPE precursors ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecularly base-stabilized four-coordinated metallacyclic organoaluminium, -gallium, and -indium compounds C5H10-Al(CH2)3NMe2 (4), C4H8Ga(CH2)3NMe2 (5), C5H10Ga(CH2)3N-Me2 (6), C5H10GaCH2CH(Me)CH2NMe2 (7), C4H8Ga(CH2)4NMe2 (8), C5H10Ga(CH2)4NMe2 (9), EtAl[(CH2)3]2NMe (10), MeGa-[(CH2)3]2NMe (11), EtGa[(CH2)3]2NMe (12), MeIn[(CH2)3]2NMe (13), and (14) have been synthesized by the reaction of [3-(dimethylamino)propyl]aluminium dichloride (1), [3-(dimethylamino)propyl]gallium dichloride (2), [3-(dimethylamino)-2-methylpropyl]gallium dichloride (3), or [4-(dimethylamino)butyl)gallium dichloride with the respective bis-Grignard reagents or by the reaction of the organometal dichlorides RMCl2 with bis[3-(chloromagnesio)propyl]methylamine or with N,N′-bis[3-(chloromagnesio)propyl]-N,N′-dimethyl ethylenediamine. Aluminium or gallium trichloride reacts with tris[3-(chloromagnesio)propyl]amine to give Al[(CH2)3]3N (15) and Ga[(CH2)3]3N (16). The 1H-, 13C-NMR and mass spectra of the new compounds as well as the X-ray crystal structure of 16 are discussed. 4, 6, and 12 have been tested successfully as MOVPE precursors.
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    Übergangsmetallkomplexe von Diazenen, XXVII. Eisencarbonyl-induzierte o-Semidin-Umlagerung von 1-Alkyl-2-aryldiazenen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1143-1148 
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    ISSN: 0009-2940
    Keywords: Ironcarbonyl complexes ; ortho-Metallation ; o-Semidine rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iron Carbonyl Induced o-Semidine Rearrangement of 1-Alkyl-2-aryldiazenesIrradiation of pentacarbonyl iron in the presence of Me3C - N=N - Ar (Ar=phenyl, p-tolyl, p-CH3OC6H4) produces in the first step ortho-metallated complexes of the type Me3C - N - N(H)RC6H3Fe(CO)3Fe(CO)3 (2a-c, R=H, Me, MeO). In a thermal consecutive step these intermediates undergo an o-semidine rearrangement to Me3C - NFe(CO)3 - Fe(CO)3N(H)RC6H3 (1a-c). The structure of 1a has been elucidated by X-ray structure analysis. Dynamic 13C-NMR spectra indicate restricted rotation of the Me3C group and hindered carbonyl scrambling for the latter and former complexes, respectively.
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    Heterogeneous Photocatalysis, IX. Zinc Sulfide Catalyzed Photoreduction of Carbon Dioxide (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1161-1162 
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    ISSN: 0009-2940
    Keywords: Semiconductor ; Photocatalysis ; Carbon dioxide ; Formate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon dioxide is catalytically reduced to formate in a suspension of zinc sulfide in water/2,5-dihydrofuran when irradiated (λ ≥ 290 nm). Turnover rates are in the range of 1.5 monolayers CO2/h. No reaction occurs at pH=12, and a very slow one at pH=3.2,5-Dihydrofuran functions as reducing agent which is oxidized to dehydro dimers. When it is substituted by 2-propanol, no CO2 reduction is observed. Semiconductor photocatalysis by a two-electron transfer from zinc sulfide to adsorbed hydrogen carbonate is assumed as the key step of CO2 fixation.
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    Cycloadditions, 47. A Route to Functionalized Cyclic Ethers by Intramolecular Cycloadditions of Unsaturated Nitro Ethers (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1181-1186 
    Details
    ISSN: 0009-2940
    Keywords: Stereoselective cyclizations ; Ethers, cyclic ; Dipolar cycloaddition ; Nitro olefins ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convenient conversion of aldehydes via nitroolefins 2 into cyclic ethers 6 fused to an isoxazoline ring involves formation of unsaturated nitroalkyl ethers 4 and subsequent intramolecular cycloaddition of an in situ-formed nitrile oxide olefin. The cyclization proceeds with stereoselective formation of trans over cis isomers in the tetrahydrofuran series and opposite stereoselectivity in the tetrahydropyran and hexahydrooxepine series, depending on the substituent R in the original nitro compound, thus providing access to stereoselectively functionalized cyclic ethers.
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    Intra- und extraannular funktionalisierte [2.2.2]Phane mit Dreifachbindung: Synthese und Eigenschaften (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1223-1227 
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    ISSN: 0009-2940
    Keywords: Cesium effect ; Clathrate ; Cyclophanes ; Acetylene, diphenyl ; Rigid-group principle ; Tolane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intra- and Extraannularly Functionalized [2.2.2]Phanes: Syntheses and PropertiesThe severely strained new cyclophanes 7b-f, consisting of bridged tolane subunits and bearing intraannular substituents R, were prepared mainly to study steric interactions of R with the “π cloud” of the triple bond. These compounds exist in a rigid twisted conformation, whereas the unsubstituted reference compound 7a and the extraannularly functionalized azo compound 9 show C2 symmetry. 9 forms a 1 : 1 clathrate with toluene.
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    Chiral Organometallic Reagents, I Stereoselective Exchange of Diastereotopic Bromine Atoms by Lithium in 1,1-Dibromo-3-(trimethylsilyloxy)alkanes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1243-1252 
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    ISSN: 0009-2940
    Keywords: Carbenoids ; Bromine-lithium exchange ; Asymmetric induction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bromine-lithium exchange in 1,1-dibromo-3-(trimethylsilyl-oxy)alkanes 4 and 6 affords the carbenoids 8 and 14, which have been added to ketones, aldehydes, arylboronates, and silylating agents. Diastereoselectivity in the generation and trapping of the carbenoids ranged between 70 - 90% for 8 and 〉90% for 14.
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    4,9,14,19-Tetrafunctionalized Pagodanes de novo Synthesis - Functional Group Manipulations (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1271-1289 
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    ISSN: 0009-2940
    Keywords: Dibenzo compounds, rigid face-to-face ; Photocycloadditions, [6 + 6] Benzo, Benzo ; Pagodanes, 4,9,14,19-tetrafunctionalized ; Functional Group Manipulations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various 4,9,14,19-tetrafunctionalized pagodanes are prepared by a de novo route commencing from appropriately substituted isodrin analogues (3, 4). With the 14,19-dimethoxypagodane-4,9-dicarboxylic esters 30/31, isolated after 16 one-pot operations (ca. 40 functional changes) in ca. 6.5% overall yield (ca. 84% per operation, ca. 93% per functional change), the scope for further functional group manipulations on the pagodane sphere is explored (e.g. diketone dicarboxylic ester 35, dimethoxy diketone 37, tetraketone 41). In two face-to-face dibenzo substrates (17, 49), clean photoequilibration with the corresponding syn-o,o'-dibenzo isomers (19, 50) (75: 25 and 80: 20, resp.) is observed upon direct excitation (λ=254 nm).
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    Die Synthese von Chlor(trichlormethyl)sulfin, Cl3C(Cl)C=SO (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1311-1312 
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    ISSN: 0009-2940
    Keywords: Anthracene adducts ; Sulfine, chloro(trichloromethyl)- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Chloro(trichloromethyl)sulfine, Cl3C(Cl)C=SOThe unstable trichlorothioacetyl chloride (2) could be trapped by a Diels-Alder reaction with anthracene to form the adduct 3, which in turn could be oxidized to the corresponding sulfine adduct 4. Finnaly, chloro(trichloromethyl)sulfine (5) was prepared in good yield by vacuum thermolysis (retro Diels-Alder reaction) of 4.
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    Organophosphorverbindungen, 48. 1-Halogen-1H-phosphirene aus Phosphaalkinen und Halogencarbenen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1207-1213 
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    ISSN: 0009-2940
    Keywords: Diazirines ; Phosphaalkynes ; Carbenes ; Phosphirenes ; [2 + 1] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organophosphorus Compounds, 48. - 1-Halogen-1H-phosphirenes from Phosphaalkynes and ChlorocarbenesHalogen-substituted carbenes (7a - i), generated by thermolysis of diazirines (11a-i), add onto phosphaalkynes (8a-c) to form the title compounds (10a-1). Initially formed 2H-phosphirenes (9) could not be detected as their subsequent conversion to the 1H-isomers 10 by a 1,3-halogen shift is very fast. Hydrolysis of 10c,e,g-i and k yields vinylphosphonous acids (17a - e). 1-Chloro-1H-phosphirenes are transformed by nucleophilic substitution into fluoro (10a,c,e → 19a-c), bromo (10c,e → 20a,b), and iodo analogs (10c,e → 21a,b) with the help of silver tetrafluoroborate, trimethylsilyl bromide, and trimethylsilyl iodide, respectively. A crystal structure analysis of 10c is reported.
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    Organische Synthesen mit übergangsmetall-Komplexen, 51. 1-Metalla-1,3,5-triene und 1-Metalla-1,3-dien-5-ine von Chrom und Wolfram durch Insertion von Alkinen in M=C- bzw. C=C-Bindungen von 1-Metalla-1,3-dienen bzw. 1-Metalla-1-en-2-inen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1229-1236 
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    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; 1-Metalla-1,3,5-trienes ; 1-Metalla-1,3-dien-5-ynes ; Insertion of alkynes into M=C and C=C bonds ; [2 + 2] Cycloaddition reactions of carbene complexes and alkynes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 51. - 1-Metalla-1,3,5-trienes and 1-Metalla-1,3-dien-5-ynes of Chromium and Tungsten by Insertion of Alkynes into M=C and C=C Bonds of 1-Metalla-1,3-dienes and 1-Metalla-1-en-3-ynes, respectively1-Metalla-1,3,5-trienes LnM=C(NEt2)-C(Me)—C(OEt)-CH=CHPh (3,4) and LnM=C(OEt)- CH=C(NEt2) - C(Me)=CHPh [5, LnM=Cr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1-metalla-1,3-dienes LnM=C(OEt) - CH=CHPh (1a, b) under very mild conditions by the insertion of the electron-rich alkyne Et2N-C ≡ C - Me (2) into the M=C and the C=C bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1-Metalla-1,3-dien-5-ynes LnM=C(NEt2) - C(Me)=C(OEt) - C ≡ CPh [9, 10, LnM=Cr(CO)5 (a), W(CO)5 (b)] are formed with high regio- and stereoselectivity on insertion of 2 into the M=C bonds of 1-metalla-1-en-3-ynes 8. X-ray data are given for the tungsten complex 3b.
    Additional Material: 1 Ill.
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    Gas-Phase Thermolysis, 14. On the Isomerization of Dimethyl Carbonate and Its Mono-, Di-, and Trithio Analogs (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1265-1270 
    Details
    ISSN: 0009-2940
    Keywords: Gas-phase pyrolysis ; Tandem mass spectrometry ; Carbonates ; Alkyl migration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-phase pyrolysis of dimethyl carbonate and its mono-, di-, and trithio analogs has been performed in the temperature range from 1253 to 1404 K applying the gas phase Curie-point pyrolysis technique. Real-time analyses have been carried out by means of mass-spectrometric techniques. The possible isomerizations of the ester functions have been studied by collisional activation mass spectrometry in combination with appropriate D, 18O, and 34S labeling. It is demonstrated that methyl group migrations can be induced pyrolytically in cases where oxygen-to-oxygen or oxygen-to-sulfur isomerizations are involved; in contrast, sulfur-to-oxygen as well as sulfur-to-sulfur isomerizations apparently do not take place.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240546
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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.19911240601
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  • 139
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    Chiral Vinyl Anions for “Carbonyl Umpolung”. Highly Stereoselective Addition of a Novel Enantiomerically Pure Vinyllithium Reagent to Aldehydes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1379-1395 
    Details
    ISSN: 0009-2940
    Keywords: Vinyl anions, chiral ; Umpolung ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vinyllithium reagent 13 and its enantiomer are generated by a bromine/lithium exchange reaction starting from dibromoalkenes 11 and 12, both available from the corresponding enantiomer of alkyl lactate. When 13 is allowed to react with aldehydes or with acetophenone, a highly stereoselective addition to the Re face of the carbonyl compounds occurs to give predominantly the diastereomers 15. Alkenes 25a,c, accessible by another bromine/lithium exchange reaction of 15a,d and subsequent protonation, can be cleaved by ozonolysis followed by reduction to afford carbinols 27a, b in 〉 98% ee. The sequence corresponds to a stereoselective introduction of a methanol d1 synthon (⊖CH2OH) or, as shown by other examples, of acyl and formyl d1 synthons (⊖CRO and ⊕CHO) into prochiral carbonyl compounds. As a consequence, 13 and its enantiomer may be regarded as highly stereoselective reagents for "carbonyl umpolung". A series of further vinyllithium reagents, 38a-g and 54/55, is treated with benzaldehyde, but none of those displays comparable enantiofacial selectivity. The prerequisites to the highly stereoselective reactions of 13 and its enantiomer are briefly discussed.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240612
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  • 140
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    Electron Diffraction Study of the Molecular Structure of 1,3-Diphenylpropane-1,2,3-trione (Diphenyl Triketone) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1411-1414 
    Details
    ISSN: 0009-2940
    Keywords: Propane-1,2,3-trione, 1,3-diphenyl- ; Electron diffraction ; Gas-crystal structure comparison ; Conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular structure of 1,3-diphenylpropane-1,2,3-trione (diphenyl triketone) has been determined by gas-phase electron diffraction at 130°C nozzle temperature. It has been found that the phenyl rings are nearly coplanar with the adjacent carbonyl groups, and the two Cph-C(O)-C(O)-C(O) dihedral angles are - 129.5 ± 0.8 and - 107.1 ± 0.8° (0° corresponds to the syn form). Bond distances (rg, Å) and bond angles (deg) with estimated total errors are C—H 1.105 ± 0.006, O = C 1.213 ± 0.003, 〈 Cph-Cph〉 1.404± 0.003, Cph-C(O) 1.478 ± 0.005, C(O)-C(O) 1.558 ± 0.004, Cph-C(O)-C(O) 120.0 ± 0.3, Cph—C(O)=O 120.8 ± 0.4, C(O)-C(O)-C(O) 117.3 ± 0.4, Cph-Cph(CO)-Cph 119.8 ± 0.6. Although there is a general agreement between the gas-phase and crystal molecular structures there are some notable differences. One of the benzene rings is slightly turned about the Cph-C(O) axis in the opposite direction in the gas molecule as compared to the crystal. This causes a marked shortening of the O… H intramolecular contact (to 2.18 Á) between the central oxygen and an ortho-hydrogen.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240615
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  • 141
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    Ring Fragmentation of Benzotriazol-1-yl Carbanions (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1431-1434 
    Details
    ISSN: 0009-2940
    Keywords: Proton transfer ; Fragmentation of rings ; Aryllithium ; Carbanions ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title carbanions 1 are shown to lose nitrogen to afford ortho-carbiminophenyl anions 4 which can be protonated by inter- or intramolecular proton transfer or react inter- or intramolecularly with other types of electrophilic center.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240618
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    Die Bildungsenthalpie des Allyl- und Methallyl-Radikals (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1453-1460 
    Details
    ISSN: 0009-2940
    Keywords: Shock tube technique ; Oxygen scavanger ; Heat of formation ; Allyl resonance energy ; Radical disproportionation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Heat of Formation of the Allyl and Methallyl RadicalThe decomposition of 1,5-hexadiene (1), 2-methyl-1,5-hexadiene (7), and 2,5-dimethyl-1,5-hexadiene (5) into allyl- (2) and methallyl radicals (6) was studied by means of the shoke tube technique with and without oxygen as scavanger. From these data and from the temperature dependence of the equilibria 1 ⇌ 2 and 5 ⇌ 6, measured between 600 and 800°C, the heat of formation of the allyl (2) and methallyl radical (6) as well as the activation parameters for the recombination and disproportionation of these radicals have been deduced.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240621
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    Rotationsbarrieren Vinyl-substituierter Olefine (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1461-1470 
    Details
    ISSN: 0009-2940
    Keywords: Allyl stabilisation energy ; Calculations, force field ; Rotational barrier, intrinsic ; Gas-phase kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational Barriers of Vinyl-Substituted OlefinesFor the vinyl-substituted olefines 1 - 14 activation parameters for the geometrical isomerisation have been determined in the gas-phase. By comparison of these barriers with the corresponding ones of the isolated double bonds, each corrected by the contribution of the steric energy to the ground and transition state, a value of 13.5 ± 1.1 kcal mol-1 for the allyl stabilisation energy (ASE), defined as replacement of alkyl by vinyl, has been derived.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240622
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    Neue planare π-Systeme, II1) Zur Darstellung und Struktur von Tetrakis(phenylethinyl)ethen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1471-1475 
    Details
    ISSN: 0009-2940
    Keywords: Polyacetylenes ; Cross conjugation ; Alkenes, tetraethynyl ; π-Systems, planar ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Planar π-Systems, II1). - On the Preparation and Structure of Tetrakis(phenylethynyl)etheneThe preparation of tetrakis(phenylethynyl)ethene (1 b) has been repeated. Among various routes to this highly unsaturated cross-conjugated π-system, the dimerization of bromide 2 via the carbene 3 is the most simple one. Full spectroscopic data for 1 b are reported for the first time, as is its X-ray structural analysis at - 95°C.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240623
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    Kurzmitteilung/Short Communication Generation and Trapping of Dichlorothioketene (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1485-1487 
    Details
    ISSN: 0009-2940
    Keywords: Thioketenes ; Flash-vacuum pyrolysis ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash-vacuum pyrolysis of 2,4-bis(dichloromethylene)-1,3-dithietane (1) at 820°C furnishes dichlorothioketene (2a) which may be trapped with cyclopentadiene (3) in a [4+2] cycloaddition. The constitution 4a of the product is confirmed by an X-ray structural analysis of the related cycloadduct 4b.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240626
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    Bis[2,3-naphthalindiolato(2-)](pyrrolidiniomethyl)silicat-Acetonitril-Solvat: Synthese sowie Kristall- und Molekülstruktur eines zwitterionischen λ5-SpirosilicatsHerrn Professor Ernst Mutschler zum 60. Geburtstag gewidmet. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1491-1496 
    Details
    ISSN: 0009-2940
    Keywords: Spirosilicates, zwitterionic ; Bond cleavage, Si - C ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis[2,3-naphthalenediolato(2 - )](pyrrolidiniomethyl)silicate Acetonitrile Solvate: Synthesis and Crystal and Molecular Structure of a Zwitterionic λ5-SpirosilicateThe zwitterionic spirocyclic bis[2,3-naphthalenediolato[2-)](pyrrolidiniomethyl)silicate (3) was synthesized and the crystal and molecular structure of its acetonitrile solvate 3 · CH3CN investigated. 3 was prepared by reaction of trimethoxy(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (9) with 2,3-dihydroxynaphthalene in acetonitrile. Reaction 9 → 3 involves a remarkable Si - C cleavage with formation of CH4. The pentacoordinate silicon atom of 3 · CH3CN is surrounded by 4 oxygen atoms and 1 carbon atom, the latter being in an equatorial position. The coordination polyhedron can be described as a distorted trigonal bipyramid (the structure is displaced by 20.5% from the trigonal bipyramid towards the square pyramid). The crystal lattice of 3·CH3CN contains centrosymmetric dimers of 3, built up by intermolecular N - H … O hydrogen bonds.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240702
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    Chemie des Dicyans: Reaktionen von Diiminosuccinonitril (DISN) mit Sulfenylchloriden und Chlortrimethylsilan sowie Cyclisierung zu Trifluormethyl-substituierten 2H-Imidazolen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1517-1520 
    Details
    ISSN: 0009-2940
    Keywords: Diiminosuccinonitrile ; 2H-Imidazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemistry of Cyanogen: Reactions of Diiminosuccinonitrile (DISN) with Sulfenyl Chlorides, Chlorotrimethylsilane and Ring Closure to Trifluoromethyl-Substituted 2H-Imidazoles4,5-Dicyano-2-hydroxy-2-(trifluoromethyl)-2H-imidazole (1) is easily prepared by treating DISN with trifluoroacetic anhydride. In the presence of 4-(dimethylamino)pyridine, however, the O-acylated derivative 2 is formed in excellent yield, while the reaction of 1 with chlorotrimethylsilane affords the O-silylated product 6. A bi-1,2,5-thiadiazole of the formula S2(CN)4Cl2 (5) is the final reaction product, when DISN is treated with sulfur dichloride in the presence of “naked” chloride ions. On the other hand the non-heterocyclic N-sulfenyl derivative 4 has readily been obtained, when DISN is treated with F3CSCl instead. Finally a procedure is described to convert DISN into the corresponding N-silylated diimine 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240706
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    Synthesis, Reactions, and Tautomerism of Ketene N,S-Acetals with Benzothiazoline Ring (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 541-547 
    Details
    ISSN: 0009-2940
    Keywords: Ketene N,S-acetals / 1H-Pyrido[2,1-b]benzothiazole, derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ketene dithioacetals 2 react with 2-aminothiophenol to afford the corresponding substituted 2(3H)-methylenebenzothiazoles 3. Some compounds 3 react with α,β-unsaturated esters to give 1H-pyrido[2,1-b]benzothiazole derivatives 4 and 5 by an electrophilic addition and cyclocondensation sequence.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19901230321
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    Über Katalysatoreffekte bei Umsetzungen α,β-ungesättigter Ketone und Ester mit Haloformen unter Phasenstransfer-Katalyse (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 583-587 
    Details
    ISSN: 0009-2940
    Keywords: Dihalocarbenes / Trihalomethane anions / Michael addition vs. carbene process / Phase-transfer catalyst, influence of structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catalyst Effects on Reactions of α, β-Unsaturated Ketones and Esters with Haloforms under Phase-Transfer CatalysisReactions of acceptor-substituted alkenes with haloform/sodium hydroxide and PT-catalyst result in dihalocarbene additions competitive to Michael additions, with or without consecutive cyclization, and further reactions. Product compositions are strongly dependent on the nature of the phasetransfer catalyst: Sterically unhindered quaternary ammonium ions and benzo-crown ethers favour processes via carbenes, large delocalized (soft) cations foster primary Michael additions. Thus, tert-butyl cis-crotonate is dichlorocyclopropanated stereospecifically with NMe4Cl. The respective stereospecific CBr2 conversion is successful only with PhHgCBr3.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19901230325
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    Complexes with sterically demanding ligands, XVI. An unexpected coupling of trimethylsilyl-substituted cyclopentadienide anion by ferric chloride (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1575-1577 
    Details
    ISSN: 0009-2940
    Keywords: Oxidative coupling of cyclopentadienide anion ; Dihydrofulvalene, molecular structure ; Migration of trimethylsilyl group ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of 1,2,4-tris(trimethylsilyl)cyclopentadienyllithium with ferric chloride in THF at -95°C leads to the formation of a thermally sensitive iron(III) complex which decomposes to the new dihydrofulvalene derivative 3,7-dihydro-1,3,3,5,7,7-hexakis(trimethylsilyl)fulvalene (1).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240716
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    An easy access to (S)- and (R)-hydroxycyclohexenone (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1677-1678 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienes, chiral ; Quinone adducts ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diels-Alder adduct obtained by addition of quinone to the chiral cyclopentadiene 2 undergoes regioselective and stereoselective reduction after hydrogenation. The 4-hydroxy ketone 3 thus formed yields the title compound 1 in a thermal retro Diels-Alder process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240732
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    Silylalkin- und Silylvinyliden-verbrückte Heterometallcluster (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 661-665 
    Details
    ISSN: 0009-2940
    Keywords: Cluster capping/Alkyne and vinylidene ligands/Silyl migration ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silylalkyne- and Silylvinylidene-Bridged Mixed Metal ClustersAttempts to incorporate silylalkynes into FeCo2 or RuCo2 clusters by means of cluster buildup or capping reactions are reported. From RuCo2(CO)11 and Me3SiC≡CMe were obtained RuCo2(CO)9(μ3-Me3SiC≡CMe) (5) and its more stable isomer RuCo2(CO)9(μ3-C=C(Me)SiMe3) (6). Of the latter the isonitrile derivative 8 was characterized by structure determination. The silylalkyne-bridged cluster 5 is very prone to desilylation forming RuCo2(CO)9(μ3-HC≡CMe) (11). The silylvinylidenebridged cluster 6 undergoes cluster expansion with CpRh(CO)2 to form RuCo2RhCp(CO)8(μ4-Me3siC≡CMe) (12), which again bears the silylalkyne ligand.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901230403
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    Neue Synthesen Trifluormethyl-substituierter Heterocyclen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 691-696 
    Details
    ISSN: 0009-2940
    Keywords: Thioacetone, hexafluoro-/1,2,4-Dithiazolines/1,2,4-Thiaselenazolines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Syntheses of Trifluoromethyl-Substituted HeterocyclesDimeric hexafluorothioacetone (HFTA) (1) reacts with thiourea or phenylthiourea to give 1,2,4-dithiazolines 2a and 2b. Similarly, 1,2,4-thiaselenazoline 3 is obtained from the reaction of 1 with selenourea. Reaction of 1 with oxamic hydrazide or thiosemicarbazide leads to acyclic molecules 4 and 5. Besides 5, the cyclic isomer 6 is also observed in solution. The N-trifluoroacetyl derivative 6a is obtained from the reaction of 5 with trifluoracetic anhydride. The structures of 2b, 3, 5, and 6a have been determined by single-crystal X-ray crystallography.
    Additional Material: 4 Ill.
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    N,N′-Dilithiobis(alkylamino)phenylborane als Synthesebausteine für viergliedrige Metallacyclen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 703-706 
    Details
    ISSN: 0009-2940
    Keywords: 4,4′-Spirobi(1,3-diaza-2-bora-4-metallacyclobutanes)/1,3-Diaza-2-bora-4-metallacyclobutanes/Metallaheterocycles with Ge, Sn, Ti, Zr ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N,N′-Dilithiobis(alkylamino)phenylboranes as Starting Materials for Four-Membered MetallacyclesReactions of N,N′-Dilithiobis(alkylamino)phenylboranes with tetrachlorides MCl4 (M = Ge, Sn, Ti, Zr) produce the 4,4′-spirobi(1,3-dialkyl-2-phenyl-1,3-diaza-2-bora-4-metalla-cyclobutane) derivatives 1a, 1b, 2b, 3a, and 3b. With diorganylmetal dihalides R2MX2(M = Sn, Zr; X = Cl, Br), the 1,3-diaza-2-bora-4-metallacyclobutanes 2a and 4 are obtained. For 3a an X-ray structure analysis has been performed.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901230409
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    Kurzmitteilung/Short Communication Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXV Synthese eines Diphosphamolybdacyclopentens durch Alkin-Insertion in die P - P-Bindung eines Diphosphamolybdacyclopropans (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1715-1716 
    Details
    ISSN: 0009-2940
    Keywords: P - P bond ; Alkyne insertion ; Diphosphamolybdacyclopentene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXV1).  -  Synthesis of a Diphosphamolybdacyclopentene by Alkyne Insertion into the P - P Bond of a DiphosphamolybdacyclopropaneInsertion of the alkyne RC≡CR (R = CO2Me) into the P - P bond of the diphosphamolybdacyclopropane (5-C5H5)-(OC)2Mo-PPh2-PAr (2) [Ar = 2,4,6-(tBu)3C6H2] results in the formation of the thermally and kinetically stable diphosphamolybdacyclopentene (η5-C5H5)(OC)2Mo-PPh2-RC = CR-PAr (3), which is characterized on the basis of mass, IR, 31P{1H}-, 1H-, and 13C{1H}-NMR spectra.
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    Lösliche bisaxial substituierte (Phthalocyaninato)ruthenium-Komplexe (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1733-1738 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanine ; Ruthenium complexes ; Pyridines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Soluble Bisaxially Substituted (Phthalocyaninato)ruthenium ComplexesSeveral attempts to prepare (tBu4Pc)Ru only led to an impure product (tBu4Pc)RuLx. This reacts quantitatively with pyridine to form (tBu4Pc)Ru(py)2, easily purified by chromatography. In addition the preparation of (tBu4Pc)RuL2 with L = pyridine, 2-picoline (2-pic), 3-picoline (3-pic), 4-picoline (4-pic), 2,5-lutidine (2,5-lut), and 2,6-lutidine (2,6-lut), respectively, is described. All complexes are characterized by spectroscopic methods including 1H-NMR spectroscopy. Not even in the cases of (tBu4Pc)RuL2 with L = 2-pic and 2,5-lut, a careful removal of the ligands L by thermogravimetric methods (TG/DTA) leads to pure (tBu4Pc)Ru. For comparison, the bisadducts PcRuL2 with L = pyridine, picolines (2-pic, 3-pic, 4-pic), lutidines (2,3-lut, 2,5-lut, 2,6-lut), and chloropyridines (2-Clpy and 3-Clpy), respectively, are prepared by treatment of PcRu with an excess of the ligand. For the first time (phthalocyaninato)iron complexes PcFeL2 with sterically hindered axial ligands, e.g. PcFe(2-pic)2, are prepared and characterized by 57Fe Mößbauer spectroscopy.
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    o-(α-Benzotriazolylalkyl)phenols: Versatile Intermediates for the Synthesis of Substituted Phenols (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1809-1817 
    Details
    ISSN: 0009-2940
    Keywords: Lithiation ; Mannich reaction ; Alkylation ; Grignard reaction ; Condensation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenols and naphthols are benzotriazolylmethylated by 1-(hydroxymethyl)-1H-benzotriazole (13) (a formaldehyde derivative) in the o- or (if both o-positions are occupied) in the p-position. The reaction can be extended to other aldehydes in the case of the naphthols. The methylene group in the o-(benzotriazolylmethyl)phenols can be lithiated (but only after trimethylsilyl protection of the hydroxy group) and then substituted by various electrophiles. The benzotriazole residues in both the primary products and in their substituted derivatives can be displaced by the alkyl anions of Grignard reagents or by hydride ions allowing the elaboration of many new types of substituted phenols.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240818
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    Cyclopropannelation of the Bicyclo[3.3.0]octane Framework. On the Chemical Significance of exo-Positioned Substituents (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1827-1830 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopropannelation ; Bicyclo[3.3.0]octane derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To facilitate the synthesis of tetracycles containing the framework 2, the reaction of the tetrabromide 8 with cyanide and bis(phenylsulfonyl)methane under various conditions was investigated. Instead of the expected twofold bridging, novel cyclopropa derivatives were obtained. Product formation is a consequence of the stereochemistry of the starting material 8, with the exo configuration of the bromomethyl substituents being the crucial factor.
    Additional Material: 1 Ill.
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    Alkylations of (R,R)-2-t-Butyl-6-methyl-1,3-dioxan-4-ones which are not Possible with Lithium Amides may be Achieved with a Schwesinger P4 Base (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1837-1843 
    Details
    ISSN: 0009-2940
    Keywords: β-Hydroxycarboxylic acids, α-alkylation of ; EPC synthesis ; 1,3-Dioxan-4-ones, enolates of ; Enolates, naked ; Schwesinger's base ; Phosphazene P4 base ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enolates A of the dioxanones specified in the title, when generated with lithium amide bases, can only be alkylated with highly reactive electrophiles, and only once. With Schwesinger's t-Bu-P 4 base (a very strong, so-called neutral base, containing 4P and 13N atoms capable of bearing a positive charge in the conjugate P4H+ cation) the dioxanone 1 can be doubly alkylated even with iodobutane (products 16, 17). The 5,6-dimethyl- and 5-benzyl-6-methyldioxanone 2 and 3 can be alkylated diastereoselectively with the formation of quaternary centers at C(5) (products 4, 8 - 14). In one case, the configuration of the product 4 obtained was determined by conversion to a β-lactone 6 and an olefin 7 (a previous assignment had to be revised). Even the 2,5,6,6-tetraalkyl-substituted dioxanone 19 could be further alkylated (→ 20 + 21). Five of the new alkylation products were hydrolyzed to the parent 3-hydroxy-carboxylic acids 5, 22  -  25. The enormous reactivities achieved with the inherently labile enolates and the P411+ counterions are discussed.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911240822
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    1,3,2-Dithiazol-2-yl-Radikale aus N-substituierten 1,3,2-Dithiazolen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 881-885 
    Details
    ISSN: 0009-2940
    Keywords: 1,3,2-Dithiazol-2-yl radicals / Sulfur-nitrogen compounds / Radicals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3,2-Dithiazol-2-yl Radicals from N-Substituted 1,3,2-DithiazolesThermolysis of N-substituted 1,3,2-dithiazoles 1,2 as well as their reactions with bases affords the corresponding 1,3,2-dithiazol-2-yl radical 3, 4. Radical 3 has been characterized by X-ray structure analysis.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901230438
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    Reaktionen von Dienolaten des (R)-2-tert-Butyl-6-methyl-4H-1,3-dioxin-4-ons mid Aldehyden und Ketonen  -  ein chirales Acetessigester-d4-Reagens (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1845-1852 
    Details
    ISSN: 0009-2940
    Keywords: (R)-3-Hydroxybutyric acid ; Aldol addition, regioselective, steric course of ; 1,3-Dioxin-4-ones, lithium dienolates of ; EPC synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Dienolates from (R)-2-tert-Butyl-6-methyl-4H-1,3-dioxin-4-one with Aldehydes and Ketones  -  a Chiral Acetoacetic Ester d4-Reagent
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    URL: http://dx.doi.org/10.1002/cber.19911240823
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    Carben-Reaktionen mit Oxetan und mit Oxetan/Methanol-Gemischen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1853-1863 
    Details
    ISSN: 0009-2940
    Keywords: Carbenes ; Oxygen ylides ; Stevens rearrangement ; Oxonium ions ; Insertion, O - H ; Ylides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of Carbenes with Oxetane and with Oxetane/Methanol MixturesEthoxycarbonylcarbene, bis(methoxycarbonyl)carbene, phenylcarbene (17a), diphenylcarbene (17b), fluorenylidene (17c), 2-furylcarbene (31a), 2-furyl(phenyl)carbene (31b), 4-oxo-2,5-cyclohexadienylidene (40), and 4,4-dimethyl-2,5-cyclohexadienylidene (53) were generated by photolysis of the appropriate diazo compounds. With neat oxetane, most of these carbenes react by competitive C - H insertion (B → A, Scheme 1) and ylide formation (B → C). 31a and 40 do not insert into C - H bonds; 31b does not attack oxetane but rearranges exclusively with formation of 26. The ylides undergo Stevens rearrangement to give tetrahydrofurans (C → D) and α´,β-elimination, leading to allyl ethers (C → E). With oxetane/methanol mixtures, the intervention of oxonium ions (H) is indicated by the formation of 1,3-dialkoxypropanes (I). The oxonium ions arise either by protonation of the ylides (C → H) or by protonation of the carbenes (B → G), followed by electrophilic attack of the carbocations (G) at oxetane (G → H). The former route is followed by the alkoxycarbonylcarbenes and by 40; the ylides derived from the remaining carbenes do not react with methanol, owing to their rapid Stevens rearrangements. Protonation of the carbenes 17b, 31, and 53 is clearly indicated by their product ratios and, for 31, by the formation of isomeric ethers (33, 36). The more electrophilic carbenes discriminate but slightly between oxetane and methanol while the more nucleophilic carbenes (17b, 31,53) prefer the protic methanol strongly over the aprotic oxetane.
    Additional Material: 5 Tab.
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    1,3-Butadienyltributylphosphonium Bromide as a Conjunctive Reagent for the Synthesis of 1,3-Dienes from Carbonyl Compounds and Gilman Cuprates (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1871-1874 
    Details
    ISSN: 0009-2940
    Keywords: Conjugate addition ; Cuprates ; 1,3-Dienes ; Wittig reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240827
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    Improved Synthesis of Fluoromethanesulfonyl Chloride (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1879-1880 
    Details
    ISSN: 0009-2940
    Keywords: Fluoromethanesulfonyl chloride ; Potassium fluoride ; Crown ether ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Introduction of fluorine into 4-chlorobenzyl chloromethyl sulfide (7) by crown-ether-assisted nucleophilic substitution furnishes 4-chlorobenzyl fluoromethyl sulfide (5), a key intermediate for the preparation of fluoromethanesulfonyl chloride (1).
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    Activation and Control of the Reaction of Dioxastannolane with Carbon Disulfide and Phenyl Isothiocyanate by the Addition of Bases (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1881-1884 
    Details
    ISSN: 0009-2940
    Keywords: Dioxastannolane ; Carbon disulfide ; Isothiocyanate ; Cycloaddition, stereospecific ; Lewis base ; 1,3-Dioxolane-2-thione ; 1,3-Dioxolan-2-imine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dioxa-2-stannolanes 1 are readlily activated by Lewis bases such as Bu3P and Et3N to give cycloadducts on reaction with carbon disulfide or phenyl isothiocyanate under mild conditions. In particular, bases play a characteristic role in the reaction with carbon disulfide to produce 1,3-dioxolane-2-thiones 2 in good yields, while spiro compounds 3 (1:2 adducts) are predominantly obtained in the absence of bases.
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    Große Übergangsmetallcluster, VIII. Wie verhalten sich trägergestützte Rh55-Cluster im Hydroformylierungsprozeß? (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1889-1893 
    Details
    ISSN: 0009-2940
    Keywords: Clusters ; Rhodium complexes ; Hydroformylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Large Transition Metal Clusters, VIII. - How Do Supported Rh55 Clusters Behave in the Hydroformylation Process?Two-shell rhodium clusters of the type Rh55L12Clx [L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2 and Na- Y-zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.
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    Synthese, Strukturen und Eigenschaften der Cyclothiaselenazenium-Kationen [Se2N2S]22+, [XSe2N2S]+, [Se2N2S]2+, [S3SeN5]+ sowie Cl2Se2N2S und SeSN2 ṁ TiCl4 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1895-1906 
    Details
    ISSN: 0009-2940
    Keywords: Selane, bis(sulfinylamido)- ; Diselane, trimethylsilyl- ; 1,3,4,2,5-Thiadiselenadiazolium ; 1,3,2,4-Thiaselenadiazete-Titanium tetrachloride ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structures, and Properties of Cyclothiaselenazenium Cations [[Se2N2S]22+, [XSe2N2S]+, [Se2N2S]2+, [S3SeN5]+as well as Cl2Se2N2S and SeSN2 and SeSN2 ṁ TiCl4Bis(sulfinylamino)selane (1), prepared from Se2Cl2 and (CH3)3SiNSO, reacts with Lewis acids such as MF5 (M = As, Sb, Nb) and BF3 to form bis(1,3,4,2,5-thiadiselenadiazolium) cations (3) with counter anions AsF-6 (3a), SbF-6 (3b), NbF-6 (3c), BF-4 (3d). Treatment of Se2Cl2 with LiN[Si(CH3)3]2 leads to [(CH3)3Si]2NSexN[Si(CH3)3]2 (x = 1, 2a: 2, 2b). From 2a and 2a and SeCl4 explosive Se4N4 is obtained. Chlorination of 3a and 3c gives [ClSe2N2S]+[MF6]- (M = As, 4a, and Nb, 4c). Analogous bromination of 3a provides [BrSe2N2S]+ [AsF6]- (4b). This type of chlorinated five-membered rings is also obtained directly from 1 and SbCl5 and PCl5 or SeCl4. The products isolated are [ClSe2N2S]+ [SbCl6]- (4d) and [ClSe2N2S]+Cl- (4e). - A covalent species 5, isomeric to 4e, is obtained from 1 and POCl3, and a four-membered ring SeSN2 ṁ TiCl4 (6) from 1 and TiCl4. When 3a or 1 is treated with a two- or threefold excess of AsF5 the stable dication [Se2N2S]2+ (7) is formed. It arises also from 4e and AgAsF6. Attempts to replace TiCl4 in 6 by AsF5 lead to [SeS3N5]+ [AsF6]- (8) with a bicyclic structure for the cation. X-ray structure analyses for 1, 4c, 4d, 4e, 5, and 8 are performed.
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    Vom Lithium-Derivat des Aminodi-tert-butylfluorsilans zu Cyclodi-, -tri- und -tetrasilazanen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1941-1945 
    Details
    ISSN: 0009-2940
    Keywords: Lithium (di-tert-butylfluorosilyl)amide ; Cyclotetrasilazane ; 1,3,5-Triamino-2,4,6-trisilazane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminodi-tert-butylfluorosilane (CMe3)2 SiFNH2 reacts with BuLi in hexane to give the lithium derivative 1, which crystallizes from TMEDA with formation of the dimer 2 [(CMe3)2SiFNHLi(TMEDA)]2. LiF elimination from 1 or 2 leads to cyclodi- (3), -tri- (4), and -tetrasilazane (6). 3 is the main product of the LiF elimination from 2 and 4 the main product resulting from 1. Cyclotetrasilazane 6 is the most planar eightmembered Si-N ring known so far. Chain compound 5 is the direct precursor of 4. The crystal structures of 2, 5, and 6 are described.From the Lithium Derivative of Amino-di-tert-butylfluorosilane to Cyclodi-, -tri-, and -tetrasilazanes
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    Molecular Structure of Trisilylmethane and Synthesis of 1,1,1-Trisilylethane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1953-1956 
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    ISSN: 0009-2940
    Keywords: Trisilylmethane ; 1,1,1-Trisilylethane ; CVD feedstock gases ; Silicon carbide, hydrogenated, amorphous (a-SiC:H) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a precursor for trisilylmethane, tris(phenylsilyl)methane is prepared by a Merker-Scott reaction of chlorophenylsilane, bromoform, and magnesium turnings in boiling tetrahydrofuran. Chlorophenylsilane is formed in a new synthesis starting from phenylsilane and hydrogen choride/AlCl3 in diethyl ether. The gas phase structure of trisilylmethane (H3Si)3CH, obtained from (PhSiH2)3CH via (BrSiH2)3CH, has been determined by electron diffraction. Data refinement confirmed a model of C3 molecular symmetry, with local C3v symmetry for the silyl groups.  -  As a precursor for 1,1,1-trisilylethane, 1,1,1-tris(phenylsilyl)ethane has been prepared similarly from chlorophenylsilane, 1,1,1-trichloroethane and magnesium and converted via 1,1,1-tris(bromosilyl)ethane into CH3C(SiH3)3.
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    Organometall-Imide - Höhervalente Derivate der d-Metall-Säuren, 1 Neue Organometall-Imide des Molybdäns und Wolframs  -  die direkte Einführung der Cyclopentadienyl-Gruppe durch Maskierung der hohen Oxidationsstufe (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1977-1979 
    Details
    ISSN: 0009-2940
    Keywords: Imido ligands ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Imido Complexes - Higher Valent Derivatives of the d-Metal Acids, 1. - New Organometallic Imido Complexes of Molybdenum and Tungsten - Direct Introduction of the Cyclopentadienyl Group by Masking the High-Oxidation StateThe molybdenum(VI)bis(tert-butylimido) complex MO(NtBu)2-Cl2 is converted into the novel organomolybdenum(VI) derivative (η5-C5H5)MO(NtBu)2Cl (1) in excellent yield. The preparation of the pyridine complex W(NtBu)2Cl2py2 (2) provides a convenient starting material for an effective synthesis of the related complex (η5-C5H5)W(NtBu)2Cl (4).
    Additional Material: 1 Tab.
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    Mehrstufige reversible Redoxsysteme, LV. Kristallstruktur des CT-Komplexes 2,5-Me2-DCNQI/TTF aus N,N′-Dicyan-2,5-dimethyl-1,4-benzochinondiimin und Tetrathiafulvalen sowie des Acceptors 2,5-Me2-DCNQI (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2001-2004 
    Details
    ISSN: 0009-2940
    Keywords: π-Acceptor ; Charge-transfer complex ; 1,4-Benzoquinone diimine, N,N′-dicyan, 2,5-dimethyl- ; Tetrathiafulvalene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LV. - Crystal Structure of the CT Complex 2,5-Me2-DCNQI/TTF from N,N′-Dicyano-2,5-dimethyl-1,4-benzoquinone Diimine and Tetrathiafulvalene and of the Acceptor 2,5-Me2-DCNQIThe crystal structure of the title compound is described and discussed in terms of a neutral non-conducting mixed-stack CT complex. X-ray data for the acceptor 2,5-Me2-DCNQI are given for comparison.
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    Polyarylenes and Poly(arylenevinylene)s, V. Synthesis of Tetraalkyl-Substituted Oligo(1,4-naphthylene)s and Cyclization to Soluble Oligo(peri-naphthylene)s2) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2091-2100 
    Details
    ISSN: 0009-2940
    Keywords: Perylene ; Terrylene ; Quaterrylene ; Oligorylenes ; Oligo(1,4-naphthylene)s ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A homologous series of oligo(1,4-naphthylene)s from the binaphthyl 6 to the sexinaphthylene derivative 10 were synthesized successively. The Pd(O)-catalyzed reaction between aryl bromides and arylboronic acids was used as a coupling method. By appropriate choice of the stoichiometry, the method allowed isolation of the intermediates 20 and 21. Under the influence of potassium in 1,2-dimethoxyethane the 1,4-bridged naphthylenes 6 - 10 were partially cyclized to perylene and terrylene units. This anionic cyclization displayed a high regioselectivity. Complete cyclization to the oligorylenes 3b, 4b and 5b was achieved under the influence of AlCl3 and CuCl2 on the bichromophoric systems 24, 25 and 28. The synthetic sequence allowed substitution by tert-butyl groups, so that the oligorylenes 2b, 3b, 4b and 5b were amenable to spectroscopic investigations. The trends in absorption maxima and fluorescence are discussed.
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    Schwefelverbindungen, 143 Synthese und Charakterisierung der neuen bicyclischen Schwefel-Kohlenstoff-Verbindungen C6H8S8, C4H4S7 und C4H4S82) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2141-2143 
    Details
    ISSN: 0009-2940
    Keywords: Sulfur-carbon compounds, bicyclic ; Titanocene chelate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfur Compounds, 143.  -  Synthesis and Characterisation of the New Bicyclic Sulfur-Carbon Compounds C6H8S8, C4H4S7, and C4H4S8The reaction of Cp4Ti2C2S4 (1) with two equivalents of the bissulfenyl chloride 1,2-C2H4(SCl)2 affords the new bicyclic compound C6H8S8 (2). Treatment of 1 with one equivalent of SxCl2 (x = 1, 2) results in Cp2TiC2S5 (3) and Cp2TiC2S6 (4), respectively, which on reaction with 1,2-C2H4(SCl)2 give the asymmetric bicyclic polysulfides C4H4S7 (5) and C4H4S8 (6), respectively.
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    Übergangsmetall-Stannyl-Komplexe, 4 Palladium- und Platin-Komplexe mit Phosphinoalkylstannyl-Chelatliganden durch oxidative Addition von Sn - C-Bindungen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2181-2184 
    Details
    ISSN: 0009-2940
    Keywords: Stannyl complexes ; Oxidative addition of Sn - C bonds ; Phosphinoalkylstannanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition Metal Stannyl Complexes, 4.  -  Palladium and Platinum Complexes with Chelatting Phosphinoalkylstannyl Ligands by Oxidative Addition of Sn - C BondsReaction of (Ph3P)4Pd with two equivalents of Ph2PCH2CH2-SnR3 (R = Ph, Me) gives the Pd(II) stannyl complexes trans-Pd(PPh2CH2CH2SnR2)2 (2) by oxidative addition of two Sn - R groups and elimination of R - R. Products corresponding to earlier steps of the reaction are obtained by the reaction of (Ph3P)2Pt(C2H4) with Ph2P(CH2)nSnR3 (n = 2, 3). The phenylderivatives Ph2P[CH2]nSnPh3 afford the Pt(II) complexes (Ph3P)(Ph)PtPPh2[CH2]nSnPh2 (3), in which the two phosphorus atoms are cis-configurated, while Ph2PCH2CH2SnMe3 gives the Pt(IV) complex cis,cis,cis-(Me)2Pt(PPh2CH2CH2SnMe2)2 (3) as stable product.
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    URL: http://dx.doi.org/10.1002/cber.19911241006
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    Mono-, Di- und Trikomplexierung von 9,10-Dihydro-9,10-dimethyl-9,10-diboraanthracen mit Fe(CO)3-Komplexfragmenten (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2203-2207 
    Details
    ISSN: 0009-2940
    Keywords: Iron, mono-, bis-, and tris(tricarbonyl) complexes ; 9,10-Diboraanthracene, 9,10-dihydro-9,10-dimethyl- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mono-, Di-, and Tricomplexation of 9,10-Dihydro-9,10-dimethyl-9,10-diboraanthracene with Fe(CO)3 Complex FragmentsReaction of 9,10-dihydro-9,10-dimethyl-9,10-diboraanthracene (1c) with (CO)3Fe(C8H14)2 gives green (CO)3Fe(η6-1c) (2c), red [(CO)3Fe]2(η4,η6-1c) (3c), and orange [(CO)3Fe]3(η4,η4,η6-1c)(4c). The constitutions of 2c, 3c, 4c are derived from NMR and MS data and confirmed by X-ray structure analyses. In 2c the Fe(CO)3 group is η6-bonded to the heterocycle of planar 1c. 3c is formed from 2c by complexation of the diene of the benzo ring in anti position. In 4c both benzo rings of 2c are η4-bonded to the Fe(CO)3 groups anti to the η6-bonded Fe(CO)3 group.
    Additional Material: 3 Ill.
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    Kohlenstoffkettenlänge als Kontrolle bei der Stabilisierung von Propargylradikalen in Mangan(III)-initiierten Reaktionen von 1-Alken-3-inen. Ein einfacher Zugang zu langkettigen 4-Acetoxy-5-alkinsäuren (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2037-2040 
    Details
    ISSN: 0009-2940
    Keywords: 1-Alken-3-ynes ; Manganese(III) acetate ; Propargyl radical ; Ligand-transfer reaction ; Electron-transfer reaction ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Control of the Propargylic Radical Stabilization by Carbon-Chain Length in Manganese(III)-Mediated Reactions of 1-Alken-3-ynes. - A Facile Synthetic Way to Long-Chain 4-Acetoxy-5-alkynoic AcidsBy investigation of reactions of 1-alken-3-ynes RC ≡ C - CH = CH2 4 with acetic acid/acetic anhydride, mediated by manganese(III) acetate, it has been found that the stabilization of propargylic radical adducts depends on the carbon-chain length of R in 4. R = C8H17 is shown to be the “critical” chain length when ligand transfer reaction appears to be the only way of stabilization of intermediates, thus providing a facile one-step access to long-chain 4-acetoxy-5-alkynoic acids. The dependence of the product ratios on the AcOH/Ac2O ratio has also been demonstrated.
    Additional Material: 3 Tab.
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    Molecular Structures of a Lithiated Schiff Base and a Related Dialkyl Ketone Imine (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2057-2063 
    Details
    ISSN: 0009-2940
    Keywords: Conformation analysis ; Lithium compounds ; Schiff bases ; Imines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ether-solvated lithium derivative of pinacolone anil (2a) is shown to be a centrosymmetric dimer (1) by X-ray diffraction analysis. Each lithium atom is bound to two nitrogen atoms, to the oxygen atom of diethyl ether, and weakly to two carbon atoms of a phenyl ring, but not to the vinyl moiety of the enamide anion. Despite conformational deconjugation, 1 is methylated at the carbon atom by methyl iodide. 1H-NMR shifts of 1 in solution are solvent-dependent. The results are discussed with respect to the “syn effect” in 1-azaallyl anions. The molecular structure of the dianil 3 of 2,2,7,7-tetramethyl-3,6-octanedione shows that a CH proton may approach the π face of an aromatic carbon atom down to a nonbonding distance of 274 A without causing much strain.
    Additional Material: 3 Ill.
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    Sterisch gehinderte Doppelbindungssysteme, 2. Über die Darstellung hochsubstituierter 1,3-Diene (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2075-2084 
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    ISSN: 0009-2940
    Keywords: 1,3-Butadienes, polyalkyl ; Allenes ; Rearrangement ; propargylic, SN2′ ; 1,3-Dienes, orthogonal ; Organocuprates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically Hindered Double Bond Systems, 2.  -  On the Preparation of Highly Substituted 1,3-DienesHighly alkylated 1,3-dienes may be prepared by treatment of 2-butyne-1,4-diol derivatives with organocuprates in good yield. Thus, the 2,3-dialkylated butadienes 6a - d are obtained by treating the diacetate 4 with two equivalents of the cuprates prepared from the Grignard reagents 5a - d with CuBr/LiBr. Analogously, meso-14 is converted into a mixture of the di-tert-butyl-2,4-hexadienes (Z,E)- and (Z,Z)-15. The procedure may be extended to the synthesis of unsymmetrically substituted 1,3-dienes by either treating the appropriate diacetates with two equivalents of the same cuprate as examplified by the conversion of 18 into 19a and 19b or by employing a stepwise approach in which only one reactive acetate leaving group is available for the cuprate reagent at any given time, thus allowing the change of the organometallic reagent in the course of the synthesis (preparation of the dienes 26 from the monoacetates 22). The mechanisms of these reactions as well as those of several reactions leading to sideproducts are discussed.
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    Zur Reaktion von Halogen(trimethylsilyl)benzolen mit Elektrophilen und Basen - Carbodesilylierung und Eliminierung als Konkurrenzreaktionen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2113-2118 
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    ISSN: 0009-2940
    Keywords: Halo(trimethylsilyl)benzenes, carbodesilylation and elimination of ; Carbodesilylation ; Elimination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of Halo(trimethylsilyl)benzenes with Electrophiles and Bases - Carbodestlylation and Elimination as Competitive ReactionsElimination to dehydrobenzenes takes place as competitive reaction in the base-catalyzed carbodesilylation of 1-halo-2-(trimethylsilyl)benzenes 1 with carbonyl compounds 2 in the presence of furans 3, 6. Elimination is preferred with increasing leaving tendency of the halides (I 〉 Br 〉 〉 Cl 〉 〉 F) and with decreasing reactivity of the carbonyl compounds. Exclusive elimination to 1,2-didehydrobenzenes - which are trapped with furans - occurs in the reaction when no electrophiles are present.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911240938
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    Darstellung von Didehydropyridinen aus (Trimethylsilyl)pyridinen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2119-2125 
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    ISSN: 0009-2940
    Keywords: Didehydropyridines, synthesis of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Didehydropyridines from (Trimethylsilyl)pyridinesHalogen-substituted (trimethylsilyl)pyridines 2, 3, 5 - 7 and trifluoromethylsulfonyloxy-substituted (trimethylsilyl)pyridines 9b, 11b are obtained from 2- and 3-halopyridines 1, 4 or hydroxypyridines 8, 10, and 12. Reactions of the 3- and 2-(trimethylsilyl)pyridines 2,9b and 11b with bases in the presence of furans 15 give only protodesilylation or hydrolysis products but no indication is found for the formation of a 2,3-didehydropyridine. 3-Bromo-4-(trimethylsilyl)pyridine (5a) reacts with KOCMe3 in the presence of furan (15a) to give a mixture of products from which the isoquinoline derivative 20 and the tert-butoxypyridines 23, 24 are formed by addition to 3,4-didehydropyridine. Under comparable conditions far higher yields of 3,4-didehydropyridines are obtained by treatment of the 3-halo-2,4-bis(trimethylsilyl)pyridines 7 with strong bases.
    Additional Material: 1 Tab.
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    2-Chloro-4,5-dihydroimidazole, VI. Annulation by Means of 4-(Dimethylamino)pyridine in the Presence of C  -  H Acids (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2145-2146 
    Details
    ISSN: 0009-2940
    Keywords: Pyridinium salts ; Ring opening, nucleophilic ; Retro-ene reaction, intramolecular ; 1H-Imidazo[1,2-α]pyrimidines, 2,3-dihydro ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Chloro-4,5-dihydroimidazole (1) reacts with 4-(dimethylamino)pyridine to yield the stable pyridinium salt 2, which on treatment with some C  -  H acids produces 1,2,3,5-tetrahydroimidazo[1,2-α]pyrimidines 6.
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    URL: http://dx.doi.org/10.1002/cber.19911240942
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    Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LXXVII Synthese, Struktur und Reaktivität von Phosphametallacyclopropanen mit isolobalen ER- (E = N, P, As, Sb) und Fe(CO)4-Bausteinen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2171-2179 
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    ISSN: 0009-2940
    Keywords: Phosphametallacyclopropanes ; Isolobal building blocks ; Lewis basic behavior ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal-Containing Heterocycles: Preparation, Properties, Reactions, LXXVII. - Synthesis, Structure and Reactivity of Phosphametallacyclopropanes with Isolobal ER (E = N,P,As,Sb) and Fe(CO)4 Building BlocksThe phosphidometallates \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} {[M] = (η5-C5H5)M-(CO)2}, resulting from the metal hydride complexes H[M]PPh2H [M = Cr (1), Mo (2), W (3)] by reduction with nBuLi, react with the geminal dihalides RECl2 to give the three-membered phosphametallacyclopropanes [ER = NC6F5 (M = Cr (1a), Mo (2a), W (3a)), PPh (M = Cr (1b), Mo (2b), W (3b)), PC6H11 (M = Cr (1c), Mo (2c), W (3c)), P-tBu (M = Cr (1d), Mo (2d), W (3d)), P(2,4,6-(tBu)3C6H2) (M = Cr (1e), Mo (2e), W (3e)), As(2,4,6-(tBu)3C6H2) (M = Cr (1f), Mo (2f), W (3f)), Sb-tBu (M = Cr (1g), Mo (2g))]. Reaction of Br2Fe(CO)4 with the corresponding dilithium compounds \documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$ Li_2 \left\{ {\left[ M \right]\dddot - PPh_2 } \right\} $\end{document} affords the phosphido-bridged heterodimetallic complexes . According to X-ray structural analyses in 2a and 2f the P - E bond distances are shortened while the Mo - E bonds are significantly elongated compared to a single bond. (OC)5CrTHF is added to the Lewis basic E atom in 2b, 2d, and 2g with loss of THF to give P-tBu (4d), Sb-tBu (4g)]. By this reaction the antimony-containing ring 2g is kinetically stabilized. Because of the low basicity of the N atom in 2a no addition was observed. The ring skeleton of 4b and 4g, undergoes no change by Cr(CO)5 coordination as shown by X-ray structural analyses.
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    Protonenaustausch in Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 gegen Triphenylphosphan-IB-Metallkationen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2191-2195 
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    ISSN: 0009-2940
    Keywords: Heterodimetallic complexes ; phosphido-bridged ; Molybdenum complexes ; Rhenium complexes ; Proton exchange, isolobal ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton Exchange in Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 Against Cationic IB Metal Phosphane SpeciesDecacarbonyldirheniumreacts with hexacarbonylbis(η-cyclopentadienyl)dimolybdenum and diphenylphosphane to give Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 (1) with a Mo  -  Re bond as ascertained by an X-ray structure analysis. The bridging H atom of the heteronuclear metal-metal bond in 1 is deprotaned with DBU. The redox condensation reaction of the obtained anion1 and triphenylphosphane IB metal cations gave Re(CO)4(μ-H)(μ-PPh2)Mo(η5-C5H5)(CO)2 [M = Au (2), Ag (3), and Cu (4)] containing an MReMo triangle. Their yields increase in the sequence of compounds 4 〈 3 〈 2. 1, 1-, and 2 were characterized by cyclovoltammetric measurements, NMR, IR, and UV/Vis spectra.
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    Synthese und Struktur von Schwefel-, Schwefelmonoxid- und Schwefeldioxid- verbrückten dimetallischen Komplexen des Typs [M(CO)(dppm)]2(μ-S)(μ-L) und [(CO)3M'(dppm)2MX](μ-L') (M = Rh, Ir; M' = Mo, W, Mn; L = SO, SO2; L' = S, SO2; X = Cl, CO) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2217-2222 
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    ISSN: 0009-2940
    Keywords: A-Frame complexes ; SO2-bridged complexes ; S, SO, and SO2 ligands ; Insertion reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Sulfur-, Sulfur Monoxide-, and Sulfur Dioxide-Bridged Dimetallic Complexes of the Type [M(CO)(dppm)]2(μ-S)(μ-L) and [(CO)3M'(dppm)2MX](μ-L') (M = Rh, Ir; M' = Mo, W, Mn; L = SO, SO2; L' = S, SO2; X = Cl, CO)The homo- and heterodimetallic complexes [M(CO)(dppm)]2-(μ-S)(μ-SO2) (M = Rh, Ir) (2a, b), [(CO)3M'(dppm)2MCl](μ-SO2) (M' = Mo, W; M = Rh, Ir) (4a - c), and [(CO)3Mn(dppm)2- Rh(CO)] (6) by passing sulfur dioxide through their solutions. The X-ray structure analysis of 5a shows the SO2 ligand in a bridging position, whereas one CO ligand is semibridging. Treatment of the same starting materials with thiirane S-oxide does not lead to the corresponding SO-bridged dimers, with the only exception of 1b, which yields the new SO complex [(Ir(CO)(dppm)]2(μ-S)(μ-SO) (3b). Passing H2S through a solution of 6, the sulfur-bridged complex [(CO)3Mn(dppm)2- Rh(CO)](μ-S) (8) is formed, accompanied by H2 elimination.
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    Kohlenwasserstoffverbrückte Metallkomplexe, XXI Addition von Tetracarbonylosmat und -ruthenat an koordinierte ungesättigte Kohlenwasserstoffe: Dreikernige Komplexe mit zwei σ,α-Allyl-, Methylallyl-, Cyclohexadien-, Cycloheptadien-, Cyclohexadienyl-, Cycloheptatrien- und „Thiophen“-Brücken (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2237-2244 
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    ISSN: 0009-2940
    Keywords: Trinuclear carbonyl complexes ; Molybdenum complexes ; Manganese complexes ; Iron complexes ; Ruthenium complexes ; Osmium complexes ; σ,α-Hydrocarbon bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrocarbon-bridged Metal Complexes, XXI. - Addition of Tetracarbonylosmate and -ruthenate to Coordinated Unsaturated Hydrocarbons: Trinuclear Complexes with two σ,α-Allyl, Methylallyl, Cyclohexadiene, Cycloheptadiene, Cyclohexadienyl, Cycloheptatrien, and “Thiophene” Bridges The addition of organometallic nucleophiles [M(CO)4]2- (M = Os, Ru) to [(Cp)(ON)(OC)Mo(allyl)]+, [Cp(OC)2Mo(butadiene)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Fe(cycloheptadienyl)]+, [(OC)3Mn(benzene)]+, [(OC)3Mn(thiophene)]+, [(OC)3-Mo(cycloheptatrienyl)]+ leads to the heterotrimetallic η1:η2-, η1:η3-, η1:η4-, η1:η5-, η1:η6-hydrocarbon-bridged complexes 1 - 7. The structures of cis-(OC)4Os[(μ-η1:η4-C7H9)Fe(CO)3]2 (4), cis-(OC)4Os[(μ-η1:5-C6H6-Mn(CO)3]2 (6), and cis-(OC)4Os-[μ-η1:η6-C7H7-Mo(CO)3]2 (7b) have been determined by X-ray analysis. The fluxional behaviour of 6 in solution has been studied in a temperature range from - 70 to +60°C. The comparison of observed and calculated 1H-NMR data indicates a 1,2-shift mechanism (ΔG+ = 49 kJ/mol).
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    Deprotonation of 5,6-Dihydro-5-methylene-4H-1,2-oxazines and Regioselective Reactions with Electrophiles (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2279-2287 
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    ISSN: 0009-2940
    Keywords: 1,2-Oxazines, lithiated ; Deprotonation ; Alkylation ; Deuteration ; Regioselectivity ; Calculations, MNDO ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5,6-Dihydro-5-methylene-4H-1,2-oxazine 1 is smoothly converted by n-butyllithium into 1-Li which reacts with electrophiles such as D2O, carbonyl compounds, dimethyl sulfide, or an azo diester to give the γ-adducts 4a-4f. On the other hand, alkylation of 1-Li occurs exclusively at C-4 of the heterocycle and provides the α-adducts 3g and 3h. These reactions require the activation of 1-Li by tetramethylethylenediamine. Treatment with allyl bromide and methyl acrylate affords mixtures of regioisomers 3 and 4. 1,2-Oxazine 5 with a conjugated C = C bond is less acidic than 1 but is also converted into 1-Li, whilst compound 6, lacking the 6-methoxy group, is not deprotonated under standard conditions. The dianion of 1,2-oxazine 7 is generated by employing an excess of n-butyllithium. This dianion displays a similar regiochemical behavior as 1-Li. Deuterium is exclusively incorporated into the γ-position to give product 8, while methylation occurs at C-4 to produce 9. 1,2-Oxazine 3g with an additional 4-methyl group can also be metalated and affords γ-adducts 10 and 11 upon reaction with D2O or acetone. Treatment with methyl iodide gives a 3:1 mixture of regioisomers 12 and 13. Deuteration of 1,2-oxazines 14 and 16 bearing a 3-CF3 or 3-CO2Et substituent requires more severe deprotonation conditions to provide the γ-adducts 15 and 17 in moderate yields. MNDO calculations of neutral 1,2-oxazines, the corresponding carbanions, and the lithium compounds allow an insight into the structure and charge distribution of these species, and also an estimation of the relative acidities. The regioselectivity of reactions of 1-Li is discussed on the basis of these semiempirical calculations and comparison with related ambident nucleophiles.
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    Photoreaktion von 3,6-Dihydrophthalsäureanhydrid mit Alkinen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2307-2313 
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    ISSN: 0009-2940
    Keywords: Cycloadditions ; Cyclobutenes ; Cyclopropanes ; Tetracyclooctanes ; Photoreactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoreaction of 3,6-Dihydrophthalic Anhydride with AlkynesThe title compound 1 and various alkynes undergo photocycloadditions to give cyclobutenes 3 and/or tetracyclooctane derivatives 4. The proportion varies from 100% cyclobutene (3d) to 100% tetracyclooctane (4e, 1) according to the substituents on the alkyne and the temperature.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911241025
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    Organische Synthesen mit Übergangsmetallkomplexen, 53 4-Methylencyclopentene und 5-Methylencyclohexenone aus „Fischer-Carben“- Chromkomplexen, Allenen und Alkine (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2335-2342 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentenes, 4-methylene-, synthesis of ; Cyclohexenones, 5-methylene-, synthesis of ; Tri(methylene)-methane chromium complexes ; [3 + 2]Cycloadditions with tri(methylene)methane complexes ; Carbene chromium complexes for organic synthesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 53.  -  4-Methylenecyclopentenes and 5-Methylenecyclohexenones from “Fischer Carbene” Chromium Complexes, Allenes, and AlkynesA method is described for the two-step construction of 4-methylenecyclopentenes 6 and 5-methylenecyclohexenones 7 from Fischer carbene chromium complexes, allenes, and alkynes. In the first step a tri(methylene)methane complex 3 is generated by the addition of the carbene chromium complex (CO)5Cr = C(0Et)Ph (1) to the allene 2. The second step involves an addition of 3 to alkynes HC≡CR [5: R = Ph (a), SiMe3 (b)] at 75°C to give 6 and/or 7 in high chemical yields. The product ratios strongly depend on the substituents R.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19911241029
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    Berichtigung/Correction Improved Synthesis of Fluoromethanesulfonyl Chloride (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2378-2378 
    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.19911241037
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  • 190
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    Stereoisomeric Dichloro[1-(hydroxyphenyl)-2-phenyl-1,2-ethanediamine]platinum(II) Complexes, Part I: Synthesis (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2381-2389 
    Details
    ISSN: 0009-2940
    Keywords: Platinum complexes ; 1,2-Ethanediamines, 1,2-diaryl- ; Antitumor activity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various erythro- and threo-configurated dichloro[1-(hydroxyphenyl)-2-phenyl-1,2-ethanediamine]platinum(II) complexes were synthesized with the hydroxy group located in either the 2-, 3-, or 4-position of the phenyl ring (38-40). The diastereoisomeric 1-(3-hydroxyphenyl)-2-phenyl-1,2-ethanediamines (31, 32) and threo-1-(2-hydroxyphenyl)-2-phenyl-1,2-ethanediamine (30) were obtained by reduction of the 1,2-diazidoethanes and subsequent ether cleavage. The configuration of the threo-1,2-diazido-1-(2-methoxyphenyl)-2-phenylethane (5) was elucidated by X-ray analysis. The reduction of the erythro-1,2-diaryl-1,2-diazidoethanes, substituted with a methoxy group in ortho or para position, results in elimination reactions with formation of side products. The desired 1,2-diaryl-1,2-ethanediamines were finally synthesized via either an aziridine derivative 21 or by reduction of the respective dioximes 27, 28. The diamine ligands were converted into the corresponding dichloroplatinum(II) complexes 38 - 40.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911241102
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    Über Metallalkyl- und -arylverbindungen, 48 Monomeres, tetrameres und polymeres Natriumfluorenid S [S = Me2N(CH2)2N(Me)(CH2)2NMe2, Me2N(CH2)nNMe2 (n = 2, 3)] (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2417-2422 
    Details
    ISSN: 0009-2940
    Keywords: Organosodium compounds ; Fluorenide carbanions ; Solvatation effects ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomeric, Tetrameric, and Polymeric Sodium Fluorenide · S [S = Me2N(CH2)2N(Me)(CH2)2NMe2, Me2N(CH2)nNMe2 (n = 2, 3)]The metallation of fluorene with sodium butanide (NanBu) in the presence of N bases yields solvated sodium fluorenide. Base adducts with bi- and tridentate N-chelating ligands have been isolated: Na(fluorenide)(pmdta) (1 [PMDTA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]n (2) [TMEDA = Me2N(CH2)2N(Me)(CH2)2NMe2], [Na(fluorenide)(tmeda)]4) (3) [TMPDA = Me2N(CH2)3NMe2]. According to X-ray diffraction studies monomeric (1), polymeric (2), and cyclic-tetrameric (3) structures are present in the crystal. These pronounced structural variations are explained on the basis of ionic contact aggregates where together with coulomb interactions the steric requirements of the ligands become rather important. Contact distances between Na ions and several C atoms of the carbanion may vary (ca. 260 - 300 pm) and definite coordination numbers become meaningless.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911241107
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    Metallkomplexe mit biologisch wichtigen Liganden, LXIII Aspartam als dreizähniger Ligand in metallorganischen Komplexen: Darstellung und Struktur von Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me] (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2429-2430 
    Details
    ISSN: 0009-2940
    Keywords: Aspartame ; L-Aspartyl-L-phenylalanine methyl ester ; Rhodium complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal Complexes of Biologically Important Ligands, LXIII1).  -  Aspartame as Tridendate Ligand in Organometallic Complexes: Preparation and Structure of Cp*Rh[O2CCH2CH(NH2)C(O)NCH(CH2Ph)CO2Me]Aspartame reacts with [Cp*RhCl2]2 in the presence of base to give the title complex 1 with the deprotonated tridendate dipeptide ester as ligand.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19911241109
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    Elektroreduktion organischer Verbindungen, 16. Elektroreduktion von ω-Halogenalkandithiosäure-methylestern (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1733-1737 
    Details
    ISSN: 0009-2940
    Keywords: Dithiolactones ; Electroreduction ; Haloalkanedithioates ; Thioacetals, semicyclic ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecular cyclization occurs on electroreduction of the methyl -haloalkanedithioates 1 in methanol. The expected semicyclic thioacetals 2 are formed according to an ECEH mechanism. The biheterocycles 12 result from dimerization of intermediate radicals whereas the semicyclic ketene dithio-acetals 13 are formed by non-electrochemical processes. The 2-(methylthio)thiolanes 2 a and 16 are obtained with much higher yields and better selectivity by co-electroreduction of the -dithio-lactones 15 in the presence of dimethyl sulfate.
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    URL: http://dx.doi.org/10.1002/cber.19901230825
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    Thermolyse von 5-Alkyliden-1,4-dihydro-5H-tetrazolen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1739-1747 
    Details
    ISSN: 0009-2940
    Keywords: [3 + 2], [4 + 2] Cycloaddition ; [2 + 1], [3 + 2] Cycloreversion ; [1,4] Hydrogen shift ; 5H-Tetrazoles, 5-alkylidene-1,4-dihydro- ; Aziridinimines ; Ketenimines ; 1,2,3-Triazoles ; 1,3-Diazabutadienes ; Pyrimidine, 3,4,5,6-tetrahydro-4-methylimino- ; Thermolysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermolysis of 5-Alkylidene-1,4-dihydro-5H tetrazolesIn benzene solution at 100°C, the isopropylidenedihydrotetrazole 1 a decomposes mainly (80%) into molecular nitrogen and the aziridinimines (E)- and (Z)-2a which are thermally unstable and afford methyl isocyanide and the imine 3a. In addition, the novel spirocyclic tetrahydropyrimidine 7a is formed (18% yield) in a [4 + 2] cycloaddition of 1a and the hypothetical intermediate 1,3-diazabutadiene 19a generated from 1a through a [1,4] hydrogen shift and loss of molecular nitrogen. The thermolysis of the neopentylidenedihydrotetrazole 1b at 100°C is more complex. Only small amounts of the aziridinimines (E)- and (Z)-2b and their decomposition products 3b and methyl isocyanide are observed. A major product is the spirocyclic tetrahydropyrimidine 7b which exhibits moderate thermal stability. Slow thermolysis of 7b affords the tetrahydropyrimidinimine 8b and methyl azide. The latter reacts with 1b in a [3 + 2] cycloaddition furnishing the spiro compound 5b which partially decomposes into the amino-1,2,3-triazole 16, thus regenerating methyl azide. This catalyzed isomerization 1b → 16 which is initiated through the thermal [3 + 2] cycloreversion of 7b involves a total of 19% of 1b. The structures of the products are elucidated by means of mass spectra and high-field NMR spectra. The mechanism of formation of the 1,3-diazabutadienes 19 from 1 is discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901230826
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    Cycloadditionsreaktionen von Organometallkomplexen, XI. Cobalta-Heterocyclen durch [2 + 3]-Cycloaddition von α-Ketocarbenen an Co-CO- und Co- CNR-Bindungen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1787-1793 
    Details
    ISSN: 0009-2940
    Keywords: α-Diazocarbonyl compounds ; Cobalt complexes ; [2 + 3] Cycloaddition ; Cobaltaheterocycles five-membered ; Protonation of exocyclic C=NR bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition Reactions of Organometallic Complexes, XI. - Cobaltaheterocycles by [2 + 3) Cycloaddition of α-Keto Carbenes to Co - CO and Co - CNR BondsThe reactions of the carbonyl(cyclopentadienyl) and (cyclopentadienyl)isocyanidecobalt complexes C5H5Co(CO)(PR3) (1-4) and C5H5Co(CNR)(PMe3) (5, 6) with α-diazocarbonyl compounds R1C(O)C(N2)R2 lead to the formation of the cobaltaheterocycles C5H5(PR3)(=O) (7-12) and C5H5(PMe3)(=NR) (13-16), respectively. For R = (S)-CH(Me)Ph a mixture of diastereoisomers RCoSCoSc is obtained. The complexes 13-16 react with HBF4 in ether to give the cations [C5H5(PMe3)-(NHR)]+ (17-20, with BF4 as anion), which on treatment with base regenerate the uncharged cobaltaheterocycles. The X-ray structural analysis of 19-RCoSc reveals the presence of a planar CoOC3 five-membered ring which presumably is formed by a [2+3] cycloaddition of an α-ketocarbene to the Co—CNR bond.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230905
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    [(Dimethylphenylsilyl)tetramethylcyclopentadienyl]thallium(I) und [(Benzyldimethylsilyl)tetramethylcyclopentadienyl]thallium(I)  -  polymere Metallorganyle mit Kettenstruktur (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1811-1816 
    Details
    ISSN: 0009-2940
    Keywords: (Cyclopentadienyl)thallium(I) complexes ; (Tetramethylcyclopentadienyl)metal complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [(Dimethylphenylsilyl)tetramethylcyclopentadienyl]thallium(I) and [(Benzyldimethylsilyl)tetramethylcyclopentadienyl]-thallium(1) - Polymeric Organometallic Compounds with Chain Structure(Dimethylphenylsilyl)tetramethylcyclopentadiene (2) and (benzyldimethylsilyl)tetramethylcyclopentadiene (3) were prepared from (tetramethylcyclopentadienyl)lithium (1) and chlorodimethylphenylsilane or benzylchlorodimethylsilane, respectively. 2 and 3 react with TIOC2H5 (4) to form [C5Me4(SiMe2Ph))TI (5) and [C5Me4(SiMe2CH2Ph)]TI (6), respectively. The 1H- and 13C-NMR spectra of the new compounds as well as the single-crystal X-ray structural analyses of the polymeric metallocenes 5 and 6 are described and discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901230909
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    Silylierungs- und Desilylierungs-Experimente mit sterisch gehinderten Stannylphosphanen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1833-1835 
    Details
    ISSN: 0009-2940
    Keywords: Tin ; Tin-phosphorus compounds ; NMR, 1H, 31P, 119Sn ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silylating and Desilylating Experiments with Sterically Hindered Stannyl PhosphanesMeP(SiMe3)2 reacts with tBu2Cl2 to give the four-membered ring (tBu2SnPMe)2 (1). Mixed silyl-stannyl-substituted phosphanes tBu3SnP(SiMe3)2 (2) and tBu2Sn[P(SiMe3)2]2 (3) are obtained by metathesis of LiP(SiMe3)2 with tBu3SnCl and tBu2SnCl2, respectively. Methanolysis of 2 and 3 yields the corresponding PH compounds tBu3SnPH2 (4) and tBu2Sn(PH2)2 (5). On heating of 5, the four-membered ring (tBu2SnPH)2 (6) is formed by a condensation reaction. The new compounds are characterized by NMR (1H, 31P, 119Sn) and mass spectroscopy.
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    URL: http://dx.doi.org/10.1002/cber.19901230913
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    Organische Synthesen mit Übergangsmetallkomplexen, 46. Alkenylcarben-Chrom- und -Wolframkomplexe; Protonierung und Aktivierung durch Elektronen-ziehende Substituenten (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1847-1852 
    Details
    ISSN: 0009-2940
    Keywords: Carbene complexes of chromium and tungsten ; Alkenylcarbene complexes, protonation of ; β-(Acylamino)alkenyl complexes of chromium ; Activated aminocarbene complexes ; 1-Metalla-1,3-dienes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic Syntheses via Transition Metal Complexes, 46.  -  Alkenylcarbene Chromium and Tungsten Complexes; Proton Addition and Activation by Electron-Withdrawing SubstituentsAlkenylcarbene complexes LnM=C(OEt)-CH=C(R)NMe2[1, LnM = Cr(CO)5, W(CO)5; R = H, CH3, C6H5] add HBF4 in ether to give novel cationic carbene complexes [Ln M=C(OEt)-CH2-C(R)=NMe2]BF4 (3) by protonation at C-2 of the =C-C=C ligand. The addition of HBF4 to 7 leads to the formation of the cyclic carbene complexes 8. Structures of 3 and 8 are assigned spectroscopically. X-ray data are reported for 8a. Protonation of 1 and 7 results in a strong deshielding of the carbene carbon atoms, which parallels an increase of reactivity at the M=C bonds. An activation of the M=C bond has also been achieved by electron-withdrawing substituents like N-acyl groups. We report on the first synthesis of [β-(acylamino)-alkenyl]carbene complexes 13, which are more reactive than β-(aminoalkenyl)carbene complexes 7.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19901230916
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    Synthese von 1,7-Diazaperylen (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1881-1884 
    Details
    ISSN: 0009-2940
    Keywords: 1,7-Diazaperylene ; Dyes, fluorescent ; Fluorescence, slid-state ; Meerwein arylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 1.7-DiazaperyleneThe hitherto unknown 1,7-Diazaperylene (2) has been prepared in a five-step synthesis from 1,5-diaminoanthraquinone (3) by a Meerwein arylation reaction. Applications as a fluorescent dye are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230920
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    Preparation of donor-acceptor-substituted vinylcyclobutanes (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1905-1909 
    Details
    ISSN: 0009-2940
    Keywords: Vinylcyclobutanes, conformational analysis of ; Wittig reaction ; Wittig-Horner reaction ; [2+2] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Methylen-1,3-dioxolane (1) and the methyl acrylates or crotonates 2 form [2+2] cycloadducts 3 which are reduced to give alcohols 6. Oxidation of these alcohols at low temperatures leads to unstable aldehydes 7, which either rearrange to dihydropyrans 5 or react with Wittig(-Horner) reagents to afford donor-acceptor-substituted vinylcyclobutanes 8. The cis-vinylcyclobutane 8g is prepared by [2+2] cycloaddition of dioxolane 1 and methyl (2E,4Z)-hexadienoate (9). The configurations and preferred conformations of the vinylcyclobutanes 8 have unequivocally been assigned on the basis of 13C-and 1H-NMR spectra.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19901230924
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