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  • Digitale Medien  (5.240)
  • Loseblatt
  • 1990-1994  (3.613)
  • 1950-1954  (1.627)
  • Inorganic Chemistry  (5.240)
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  • Digitale Medien  (5.240)
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  • 101
    Digitale Medien
    Digitale Medien
    Synthesis of Platinum(II) Alkane- and Arenethiosulfinato Complexes  -  Crystal Structure Analysis of N-[(Benzylsulfinyl)thio]phthalimide (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 97-99 
    Details
    ISSN: 0009-2940
    Schlagwort(e): (Sulfinylthio)phthalimides ; Thiosulfinato complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The oxidative addition of N-[(alkyl- and arylsulfinyl)thio]-phthalimides 3a-d to Pt(PPh3)2(C2H4) gives the platinum(II) thiosulfinato complexes cis-Pt[(S-S(O)-R)(Nphth)(PPh3)2] 4a-d; the structure of N-[(benzylsulfinyl)thio]phthalimide (3c) has been characterized by X-ray crystallography.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270116
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  • 102
    Digitale Medien
    Digitale Medien
    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 119-126 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Host-guest complexes ; Molecular-dynamics (MD) simulation ; Enantioselective gas chromatography ; Cyclodextrins ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The energies of complexation of methyl (R)/(S)-2-chloropropionate [(R)/(S)-2] with heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1) and the structures of the corresponding complexes were determined by molecular-dynamcis (MD) simulations at 300 and 333 K. The geometry of the complexes, the conformations of complexed and uncomplexed 1 and (R)/(S)-2 and the closest H-H distances between host and guest in the complexes were determined from the trajectories. The results correspond to the experimental findings from enantioselective gas chromatography.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270120
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  • 103
    Digitale Medien
    Digitale Medien
    Benzoanellated Centropolyquinanes, 14. Synthesis of Tribenzotriquinacene by Stereocontrolled Cyclization of Phenyl-Substituted Cs-Diindans (4bα,9,9aα,10-Tetrahydroindeno[1,2-α]indenes)Dedicated to Professor Ekkehard V. Dehmlow on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 151-164 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Triquinacenes ; Indenoindenes ; syn Elimination ; thermal ; Conformational effects ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of tribenzotriquinacene 4 by a stepwise cyclization strategy involving phenyl-substituted diindan intermediates is discussed in detail. Based on the determination of the anti (α) stereochemistry of the previously known phenyldiindanone 8 by standard electron impact mass spectrometry as well as on synthetical evidence (8 → 12 → 14), the conversion of 8 to the syn (β) phenyl-substituted isomer 20 by means of dehydrogenation-rehydrogenation sequences has been achieved. In particular, the preparation of the isomeric diindenones 15 and 16 as key synthetic intermediates by thermal syn elimination of the corresponding phenylsulfinyl and phenylseleninyl ketones 22 and 25 is described and contrasted to a bromination/dehydrobromination approach adopted from a previous report. The synthesis is completed by reduction of 20 to diindanol 27 followed by cyclodehydration, giving 4 in 14-19% overall yield from 8. Non-cyclizing dehydration of 27 and the isomeric diindanol 9 gives the Δ4b,9-diindene 30 as the most stable non-cyclized isomer of 4. The steric effect of the syn- or anti-oriented phenyl substituents on the preferred conformation of the diindan skeleton is deduced from the contrasting vicinal 1H-1H spin coupling observed for the stereoisomers, e.g. the 9-phenyldiindans 28 and 29.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270124
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  • 104
    Digitale Medien
    Digitale Medien
    Tri-tert-butyl(trimethylgermyl)cyclobutadien und Tri-tert-butyl(trimethylgermyl)tetrahedran (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 201-204 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Diazo compounds ; Homologation ; Valence isomerization ; Germanium compounds ; Tetrahedranes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Small Rings, 80[1].  -  Tri-tert-butyl(trimethylgermyl)cyclobutadiene and Tri-tert-butyl(trimethylgermyl)tetrahedraneIn the course of our research on silyl-substituted diazo compounds as precursors of cyclobutadienes and tetrahedranes the synthesis of the title compounds 16 and 17 has also been accomplished. Their properties are comparable to those of the silyl-substituted homologous compounds. Tri-tert-butyl(trimethylgermyl)tetrahedrane (17) melts without decomposition at 143°C and thus proves to be as stable as tri-tert-butyl(trimethylsilyl)tetrahedrane. The interconversion of the rectangular forms of tri-tert-butyl(trimethylgermyl)cyclobutadiene (16) proceeds with an activation energy below 4 kcal/mol, which is nearly the same as of tri-tert-butyl(trimethylsilyl)cyclobutadiene.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270128
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  • 105
    Digitale Medien
    Digitale Medien
    (1α,2α, 7α,8α,12α,17α,18α,19α)-Heptacyclo[17.3.1.18,12.05,23.06,18.07,17.016,24]-tetracosa-5(23),16(24)-dien, ein hyperstabiles Alken (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 219-221 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Alkenes ; hyperstable ; Hydrogenation ; catalytic ; Hydrocarbons ; concave ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (1α,6α,7α,8α,12α,17α,18α,19α)-Heptacyclo[17.3.1.18,12.05,23.06,18.07,17.016,24]tetracosa-5(23),16(24)-diene, a Hyperstable AlkeneHydrogenation of the cis-photodimer 1 of acenaphthylene yields the title compound 2, which, though still containing two double bonds, undergoes no further hydrogenation or reaction with bromine for steric reasons. The cyclobutane ring of 2 shows strong steric distortions as revealed by X-ray analysis as well as by force-field and semiempirical MO calculations.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270131
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  • 106
    Digitale Medien
    Digitale Medien
    Fe(I)-Mediated Regio- and Stereoselective C—C/C—H Bond Activation of Internal Methylene Groups of α,ω-Diphenylalkanes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 261-265 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Bond activation ; C—H ; C—C ; Iron chemistry ; Reaction mechanisms ; Chelate effects ; Tandem mass spectrometry ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For three α,ω-diphenylalkanes the mechanistic details of the Fe+-mediated activation of C—H and C—C bonds in the gas phase have been elucidated by isotopic labelling experiments. The unimolecular reactions, i.e. dehydrogenation of the alkane chain, formation of ethylene from internal methylene groups, and generation of toluene, proceed largely with high selectivity. Particularly interesting are the results for the dehydrogenation of the Fe+ complex 3-Fe+ of 1,8-diphenyloctane which involves to 93% the internal methylene groups C-4/C-5. In addition, the study of the stereoisotopomers 3c-d provides evidence for the operation of isotopically sensitive branching (“metabolic switching”) in the reaction, and the analysis of the data suggests that the selectivity of the reaction is, most likely, due to a sandwich-type structure.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270136
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  • 107
    Digitale Medien
    Digitale Medien
    Ein neuartiger chiraler Synthesebaustein mit Neopentangerüst: Chemo-enzymatische Darstellung von (R)-CH3C(CH2OSO2CF3)(CH2Cl)(CH2Br) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 271-274 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Pig liver esterase ; Enantioselective hydrolysis ; Asymmetrized neopentane ; Reactive chiral building block ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A Novel Chiral Building Block with Neopentane Framework for Synthesis: Chemo-Enzymatic Preparation of (R)-CH3C(CH2OSO2CF3)(CH2Cl)(CH2Br)The pig liver esterase (PLE) catalysed hydrolysis of the prochiral malonic ester (BzlOCH2)(Me)C(COOMe)2 (1) leads to its chiral monoester 2 in selectivities up to 81% ee. Compound 2 is an ideal entry point for the enantioselective synthesis of 1,1′,1″-substituted neopentanes CH3C(CH2X)-(CH2Y)(CH2Z) with three different leaving groups, X, Y, and Z. CH3C(CH2OSO2CF3)(CH2Br)(CH2Cl) (8) is a versatile reactive building block for the asymmetric synthesis of compounds containing the neopentane-C5 skeleton.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270138
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  • 108
    Digitale Medien
    Digitale Medien
    Übergangsmetall-Silyl-Komplexe, 48. Synthese neuartiger heteronuklearer Silyl-Zweikernkomplexe (OC)3(R3Si)Fe(μ-PR′R″)Pt(1,5-COD)(Fe-Pt), Phosphan-Austauschreaktionen an (OC)3 (R3Si)Fe(μ-PR′R″)Pt(PPh3)2(Fe - Pt) und Darstellung der Dihydrido-Komplexe [(OC)3Fe(μ-PPh2)(μ-H)2Pt(PR3)2][BF4](Fe - Pt) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 295-304 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Heterobimetallic complexes ; Iron complexes ; Platinum complexes ; Silyl complexes ; Phosphido bridges ; Hydrido complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Transition Metal Silyl Complexes, 48[1]. - Synthesis of the New Heterobimetallic Dinuclear Silyl Complexes (OC)3(R3Si)-Fe(μ-PR′R″)Pt(1,5-COD)(Fe-Pt), Phosphane Exchange Reactions of (OC)3(R3Si)Fe(μ-PR′R″)Pt(PPh3)2(Fe-Pt), and Preparation of the Dihydrido complexes [(OC)3Fe(μ-PPh2)(μ-H)2Pt(PR3)2][BF4](Fe-Pt)The dinuclear, silyl-substituted complexes (OC)3(R3Si)Fe(μ-PR′r″)Pt(1,5-COD) (1) [μ-PR′R″ = PPh2, PCY2, PHPh; SiR3 = SiPh3, Si(OMe)3] were prepared in high yields by the oxidative addition of the hydrido complexes (OC)3(PHR′R″)Fe(H)-SiR3 to Pt(1,5-COD)2. Upon reaction of (OC)3(R3Si)Fe(μ-PR′R″)Pt(PPh3)2 [μ-PR′R″ = PPh2, PHCy; SiR3 = SiPh3, SiPh2Me, SiPhMeCl, Si(OMe)3] with two equivalents of PR‴3 (PMe3, PBu3, PEt3) or with one equivalent of chelating di-phosphanes (vdpp, dppe, dppm) both PPh3 ligands are displaced, and (OC)3(R3Si)Fe(μ-PR′R″)Pt(PR‴3)2 or (OC)3(R3Si)-Fe(μ-PR′R″)Pt[(PPh2)2X] (X = C=CH2, C2H4, CH2) are formed, respectively. When one equivalent of PMe3 is used, only the PPh3 ligand trans to the μ-PPh2 bridge is substituted, and (OC)3(Ph3Si)Fe(μ-PPh2)Pt(PPh3)(PMe3 is formed. The 1,5-COD ligand in 1 is displaced by P(OR)3 to give (OC)3-(Ph3Si)Fe(μ-PPh2)Pt[P(OR)3]2 (R = Me, Ph). The complexes (OC)3(Ph3Si)Fe(μ-PPh2)Pt(PMe3)2and (OC)3(Ph3Si)Fe(μ-PPh2)Pt[(PPh2)2C=CH2] were characterized by X-ray structure analysis. The short Fe-Si distances [233.0(2) and 235.6(3) pm] and the infrared v(CO) absorptions indicate that the Fe-Pt bonds are quite polar. Protonation of (OC)3(Me2-PhSi)Fe(μPPh2)Pt(PPh3)2 with CF3COOH gives the hydrido-bridged complex [(OC)3(Me2PhSi)Fe(μ-PPh2)(μ-H)Pt-(PPh3)2][O2CCF3]. Upon addition of an excess of HBF4 · Et2O to (OC)3(R3Si)Fe(μ-PPh2)Pt(PPh3)2 (R = Ph, OMe), (OC)3-Si)Fe(μ-PPh2)Pt[Pt[P(OMe)3]2 or (OC)3(Ph2MeSi)Fe(μ-PPh2)-Pt(dppe) R3SiF is split, and the corresponding μ-dihydrido complexes [(OC)3Fe(μ-PPh2)(μ-H)2Pt(PR3)2][BF4] are obtained.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270204
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  • 109
    Digitale Medien
    Digitale Medien
    From Azole - Borane Adducts to Azaboles  -  Molecular Structure of an Imidazabole (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 343-346 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Azole-borane adducts ; Azaboles ; Imidazabole ; X-ray analysis ; NMR, multinuclear ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Elimination of H2 from the imidazole - borane adduct 1 leads to a mixture of the imidazaboles 2 and 2′. The symmetrical isomer 2 (two H2BNC fragments) is isolated in pure state and characterized by an X-ray structure analysis (monoclinic, space group P21). 2-(Trimethylstannyl)thiazole (3a) and 1-methyl-5-(trimethylstannyl)-1,2,4-triazole (3b) react with triethylborane to form adducts 4 from which, in the presence of an excess of Et3B, tetraalkyltin is elimated to give the thiazabole 5a and the triazabole 5b, respectively. Multinuclear 1H-, 11B-, 13C-, 14N-, and 119Sn-NMR spectroscopy serve for following the reactions (compounds 3 to 5) and to characterize all final products.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270210
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  • 110
    Digitale Medien
    Digitale Medien
    Stabilization of Triorganotin Cations  -  Competition between Intramolecular Coordinative O—, S— or N—Sn Bonds and Side-on π Coordination to C≡C Bonds (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 333-342 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Tin cations ; triorgano ; Coordination ; s̰ and π ; 1,1-Organoboration ; 1-Alkynyltin compounds ; functionally substituted ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Di-1-alkynyltin compounds 1 of the type Me2Sn(C≡CUL)2 [LU = 2-pyridyl (a), Me2NCH2 (b), MeOCH2 (c), MeOCH=CH (d), EtSCH2 (e)] were prepared and the 1,1-organoboration of 1 with triethyl- (2a) and triisopropylborane (2b) has been studied. The first detectable intermediates were in all cases zwitterionic compounds 3 (from Et3B) and 4 (from iPr3B) with a cationic triorganotin fragment, stabilized by coordinative s̰ L—Sn bonds and by side-on coordination to the C≡C bond of an alkynylborate moiety. The nature of this stabilization has been established by three X-ray analyses (3b, 4b, and 4d) in the solid state and by multinuclear NMR (1H-, 11B-, 13C-, 15N-, 119Sn NMR) in solution. The comparison of the molecular structure of 3b, 4b, and 4d with that of intermediates without functional groups shows that the distance of the tin atom to the C≡C bond is elongated. However, the planar arrangement of all relevant atoms proves that the side-on coordination of the tin atom to the C≡C bond is still present. These intermediates 3 and 4 rearrange to stannoles 5, 6 and/or to 1-stanna-4-bora-2,5-cyclohexadienes 9, 10. In the case of 3b and 3e, 119Sn NMR indicates that dialkenyltin compounds 7b and 7e are also formed as minor products. In the case of 3e, the 3-stannolene 8e is one of the final products. In the stannoles 5 and 6 a coordinative L—B bond is evident, and there is NMR spectroscopic evidence of a weak coordinative L - Sn bond.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270209
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  • 111
    Digitale Medien
    Digitale Medien
    Messung der Donorstärke substituierter 1-Naphthole (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 393-400 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cyclovoltammetry ; Charge-transfer complexes ; HOMO energy ; Naphthols ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Measurement of the Donor Strength of Substituted 1-NaphtholsThe oxidation potential of various substituted naphthols is available by cyclovoltammetry. The donor strength of substituents on the oxidation potential may be explained on the base of substituent increments. When correlating the oxidation potential with the transition energy of charge transfer complexes with TCNE, 1-naphthols with 8-alkoxy substituents and naphthols without oxygen in position 8 are giving different correlation curves. The experimental values correlate well with semiempirically calculated HOMO energies. Our measurements allow to predict the oxidation potentials of hitherto unknown substituted 1-naphthols with high probality. Thus, it may be possible to synthesize 1-naphthols with a defined oxidation potential.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270216
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  • 112
    Digitale Medien
    Digitale Medien
    Benzoanellated Centropolyquinanes, 15. Benzoanellated Fenestranes with [5.5.5], [5.5.5.6], and [5.5.5.5] Frameworks: The Route from 1,3-Indandione to FenestrindanDedicated to Professor Eckehard V. Dehmlow on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 409-425 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Fenestranes ; Polyquinanes ; Centropolyindans ; Polycyclic compounds ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis and spectroscopic characterization of several benzoanellated [5.5.5]-, [5.5.5.6]-, and [5.5.5.5]fenestranes, including the parent difuso-centrotriindan 7, the parent tetrafuso-centrotetraindan 8 (“fenestrindan”) as well as the tribenzo[5.5.5.6]- and tribenzo[5.5.5.5]fenestranes 27 and 35, are described and discussed in full experimental detail. The highly efficient twofold cyclodehydration of 2,2-dibenzyl-1,3-indandiol 15 and the related spiro-condensed 1,3-indandiols 23 and 29 is the keystep of the synthetic strategy. The new synthetic variant involving the one-pot cyclodehydration/deketalization of the dispiro-ketal diol 29 is particularly convenient. In the case of 7, an alternative Lewis acid-catalyzed double cyclization has been developed. Stereochemical aspects of the 1,3-indandiols and the key tribenzo[5.5.5.6]fenestranes 24 and 25 are discussed in detail.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270218
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  • 113
    Digitale Medien
    Digitale Medien
    Trimethylsilylierte 1,4-Diborinane und 1,3-Diborolane - Bildung, Isomeren-Trennung und Charakterisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 813-820 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Hydroboration of 1-alkinylsilanes ; Ethyldiboranes(6) ; Alkyl substituent exchanges ; BH-borane-catalysed ; 1,4-Diborinanes, trimethylsilyl-substituted, isomers of ; Lewisbase - 1,4-Diborinanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Trimethylsilylated 1,4-Diborinanes and 1,3-Diborolanes - Formation, Isomer Separation, and CharacterisationMe3SiC≡CH (A) reacts with excess (Et2BH)2 via the compounds 1, 1′ and 2, 2′ to yield a mixture of four regio- and stereoisomeric 1,4-diethyl-2,5(6)-bis(trimethylsilyl)-1,4-diborinanes (3a-d) and minor amounts of 1,3-diethyl-2-methyltrans-2,5-bis(trimethylsilyl)-1,3-diborolane (4a). The 2,5-ee-(Me3Si)2 compound 3d is isolated as the adduct 3d(Pic)2 (X-ray structure analysis), from which pure 3d is obtained with Et2O-BF3. 3d and Me3P form equilibria of the 1:1 and 1:2 addition compounds 3d(Me3P)n (n = 1,2) at room temperature. Me3SiC≡CMe (B) reacts with (Et2BH)2 via 5 to give 6-10, and Me3SiC≡CSiMe3 (C) reacts with (Et2BH)2 to form the ring compounds 12 and 13 via the presumably threo/erythro mixture of 11a and b.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270504
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  • 114
    Digitale Medien
    Digitale Medien
    Synthesis and Structure of N-Silylated Anilines (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 841-844 
    Details
    ISSN: 0009-2940
    Schlagwort(e): N-Silylanilines ; Anilines, N-silylated ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The new N-(arylsilyl)anilines 1-5 have been obtained by the reaction of aryl(halo)silanes with the corresponding anilines in the presence of the auxiliary base triethylamine. The benzene parts of the anilines have been chosen such that their fluoro, methyl, and methoxy substituents exert different electronic effects. The molecular structures of the monosilylated anilines 3 and 4 have been determined by single-crystal X-ray diffraction analysis. The coordination geometry of the nitrogen atoms have been found to be planar. Heteronuclear NMR spectra (1H, 13C, 15N, 29Si) have been recorded and the structural results correlated with the one-bond coupling constant 1J(29Si15N).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270509
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  • 115
    Digitale Medien
    Digitale Medien
    Electroorganic Synthesis, 58. Synthesis of Substituted Benzoquinones and their Use for Mediated Electrochemical Conversions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 859-873 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Benzoquinones, substituted ; Cyclic voltammetry ; Cathodic dioxygen reduction, mediated ; Anodic Wacker oxidation, mediated ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hydroxy- (1a-3a) and hydroxyalkyl-substituted benzoquinones (6a-8a, 27a), suited to be immobilized by esterification with polyacrylic acid, are prepared. Their cathodic reduction potential Ep,c (1) correlates linearly with their substituent constant. The cathodic reduction of dioxygen and the palladium(II)-catalyzed anodic oxidation of alkenes are mediated by the benzoquinones 7b, 8b and 27b, respectively.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270513
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  • 116
    Digitale Medien
    Digitale Medien
    Synthesen und Reaktionen acyclischer fluororganischer Thiocarbenium-IonenHerrn Prof. Dr. W. Sawodny zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 597-603 
    Details
    ISSN: 0009-2940
    Schlagwort(e): (Trifluoromethylthio)carbon ; Carbenium ions ; One-electron oxidation ; Superacidic systems ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Syntheses and Reactions of Fluoroorganic Acyclic Thiocarbenium IonsHerrn Prof. Dr. W. Sawodny zum 60. Geburtstag gewidmet.Arsenic pentafluoride oxidizes (F3CS)4C (1) but not (F3CS)2C = C(SCF3)2 (2) to yield the stable salt (F3CS)3C+AsF-6 (3). It reacts with halide ions to form (F3CS)3CX (3a-c, X = F, Cl, Br). Iodide is oxidized to iodine with formation of (F3CS)3CC(SCF3)3 (4) which reacts with nitrogen dioxide to give (F3CS)3CNO2 (3e). - (F3CS)3C+AsF-6 (3) removes from (F)-SCF3 (5a) a ring-bound fluorine atom to afford (F3CS)3CF and -SCF3]+AsF-6 (5). When (F3CS)3CCl (3b) is treated with AsF5, 3 and [(F3CS)2-CCl]+AsF-6 (6) are formed in a 2:1 molar ratio. The latter reacts with F- or Cl- to give (F3CS)2CClX (6a,b; X = F, Cl). AsF5 is capable of abstracting a fluoride ion from (F3CS)3 - n Cln,CF only if n = 0 or 1. For n = 2 no similar reaction takes place, but with AlCl3 in BCl3 halogen exchange to F3CSCCl3 (7b) is observed. - Alkylation of (F3CS)2C=S (8) with H3CF/AsF5 yields [(F3CS)2CSCH3]+AsF-6 (9), which adds a fluoride ion to give (F3CS)2(H3CS)CF (9a). The molecular structures of (F3CS)2C = C(SCF3)2 (2) and (F3CS)3CC(SCF3)3 (4) have been determined by X-ray diffraction methods.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270403
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  • 117
    Digitale Medien
    Digitale Medien
    Metallkomplexe mit biologisch wichtigen Liganden, LXX. Synthese, Stereochemie und Reaktionen von Ruthenium(II) und Osmium(II)-Komplexen mit α-Aminocarboxylat-LigandenHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 615-620 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Ruthenium complexes ; Osmium complex ; Hydrido complexes ; α-Amino acids ; Oxidative Addition ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Metal Complexes of Biologically Important Ligands, LXX[1].- Synthesis, Stereochemistry and Reactions of Ruthenium(II) and Osmium(II) Complexes with α-Amino CarboxylatesHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.The reactions of MHCl(CO)(PPh3)3 with salts of α-amino acids give the hydrido-N,O-chelate complexes MH(CO)(NH2CHR-COO)(PPh3)2 (1a-g;) M = Ru, Os). Complexes 1a-c can alternatively be prepared by oxidative addition of the appropriate α-amino acid to Ru(CO)3(PPh3)2. The crystal structure of 1b has been determined by an X-ray structural analysis. The leucinato compound 1c is an effective catalyst for the decomposition of formic acid. In contrast, reactions of RuHCl-(CO)(PPh3)3 with α-amino acids afford the chloro-N,O-che-late complexes RuCl(CO)(NH2CHRCOO)(PPh3)2 2a-h. The decomposition reactions of 2c, 2g and2h have been investigated.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270406
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  • 118
    Digitale Medien
    Digitale Medien
    Bis[2,3-naphthalenediolato(2  -  )](pyrrolidiniomethyl)germanate - Tetartoacetonitrile, the First Zwitterionic λ5-Germanate: Synthesis and Crystal Structure Analysis (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 643-646 
    Details
    ISSN: 0009-2940
    Schlagwort(e): λ5-Germanate, zwitterionic ; Germanium, pentacoordinate ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The zwitterionic spirocyclic λ5-germanate bis[2,3-naphthalenediolato(2 - )](pyrrolidiniomethyl)germanate (8) was synthesized and the crystal structure of its tetartoacetonitrile solvate 8 · 1/4 CH3CN studied by single-crystal X-ray diffraction. Compound 8 was prepared by reaction of (MeO)3-GeCH2NC4H8 (11; NC4H8 = pyrrolidino) with two equivalents of 2,3-naphthalenediol (isolated as 8 · 1/4 CH3CN; yield 92%). The coordination polyhedron around the pentacoordinate germanium atom of 8 · 1/4 CH3CN can be described as a strongly distorted trigonal bipyramid (the structure is displaced by 38.9% from the ideal trigonal bipyramid towards the ideal square pyramid), the carbon atom occupying an equatorial position. In the crystal lattice of 8 · 1/4 CH3CN, the zwitterions form intermolecular N—H⃛O hydrogen bonds leading to the formation of dimers. 1H- and 13C—NMR studies revealed that 8 also exists in solution ([D6]DMSO).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270410
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  • 119
    Digitale Medien
    Digitale Medien
    Thermally Initiated Free-Radical Chain Addition of Alkanes to Alkynes, II. Kinetics of the Addition of Cyclohexane to Phenylethyne under Supercritical Fluid Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 673-675 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Radicals ; Addition ; Alkynes ; Kinetics ; Supercritical fluid conditions ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the addition of cyclohexane (2) to phenylethyne (1) proceeding via 2-cyclohexyl-1-phenylethenyl radical (3) to give 1-cyclohexyl-2-phenylethene (4) was investigated in the temperature range from 260 to 340°C. The radical chain is initiated by a bimolecular reaction of cyclohexane with phenylethyne to give a cyclohexyl radical and a 1-phenylethenyl radical. The physical state of the reaction mixture was varied from liquid to supercritical and to gasphase conditions. No effect on the reaction rate constant near the critical point was observed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270416
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  • 120
    Digitale Medien
    Digitale Medien
    Diastereoselective Radical Bromination of 5,6-Dihydro-4H-1,2-oxazines and Subsequent Substitution Reactions with Nitrogen Nucleophiles (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 685-689 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1,2-Oxazines ; Bromination, radical ; SN2 reaction ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 5,6-Dihydro-4H-1,2-oxazines 1a-b, 2, and 3 are easily brominated at C-4 with N-bromosuccinimide/dibenzoyl peroxide in tetrachloromethane. The bromo substituent is incorporated with surprisingly high diastereoselectivity trans to the substituent at C-6. 4-Bromo-5,6-dihydro-4H-1,2-oxazines are useful reagents for substitution reactions with N-nucleophiles such as primary amines and azide ions. Inversion of configuration at C-4 provides derivatives of 4-amino-1,2-oxazines with uniform relative configuration. As a minor byproduct the dibromo adduct 7 is obtained by bromination of 3. The dehydrohalogenation of this compound allows the synthesis of the 4-bromo-6H-1,2-oxazine 12. The presented reaction sequence thus constitutes an “umpolung” reaction that allows the introduction of nucleophiles into a position of the oxazine ring that so far was accessible only for electrophiles. The diastereoselectivity of the bromination reaction is discussed.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270418
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  • 121
    Digitale Medien
    Digitale Medien
    Organische Synthesen mit Übergangsmetallkomplexen, 70. [2-(Galactopyranosylamino)ethenyl]carben- und 3-(Galactopyranosylamino)-1,2-propadienyliden-Komplexe durch 3-Addition von 2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamin an Alkinylcarben-Komplexe (M = Cr, W).  -  Atropisomere Galactopyranosyl-Pyrrole durch Reaktion von [2-(Galactopyranosylamino)ethenyl]carben-Komplexen mit Isocyaniden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 725-729 
    Details
    ISSN: 0009-2940
    Schlagwort(e): [2-(Amino)ethenyl]carbene complexes ; 3-Amino-1,2-propadienylidene complexes ; (2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamine, carbene complexes of ; Ketene imines ; Isocyanides ; Pyrroles ; Alkynylcarbene complexes of chromium and tungsten ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organic Syntheses via Transition Metal Complexes, 70[1].  -  [2-(Galactopyranosylamino)ethenyl]carbene and 3-(Galactopyranosylamino)-1,2-propadienylidene Complexes on 3-Addition of 2,3,4,6-Tetra-O-pivaloyl-β-D-galactopyranosylamine to Alkynylcarbene Complexes (M = Cr, W).  -  Atropisomeric Galactopyranosyl Pyrroles by Reaction of [2-(Galactopyranosyl-amino)ethenyl]carbene Complexes with IsocyanidesEnantiomeric pure (2-aminoethenyl)carbene complexes LnM=C(OEt)—CH=C(Ph)NHR* (Z)-3 and 3-amino-1,2-propadienylidene complexes LnM=C=C=C(Ph)NHR* 4 [R* = 2,3,4,6-tetra-O-pivaloyl-β-D-galactopyranosyl] are obtained by the addition of galactopyranosylamine R*-NH2 2 to the corresponding alkynylcarbene complexes LnM=C(OEt)—C≡CPh 1 [LnM = (CO)5Cr, (CO)5W]. Treatment of (Z)-3 with two equivalents of tert-butyl isocyanide (5) affords isocyanide complexes 6 and ketene imines 7. The latter cyclize spontaneously to give galactopyranosylpyrroles 8 which form stable atropisomers 8A and 8B.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270423
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  • 122
    Digitale Medien
    Digitale Medien
    Molekulare Pinzetten aus Cyclophan-Bausteinen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 743-757 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Bond formation ; C—C / Host-Guest complexation ; Metacyclophanes ; Conformation, syn, anti ; Hagihara coupling ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Molecular Tweezers from Cyclophane Building BlocksMolecular tweezer compounds 1-6 with convergent carboxyl groups are prepared from suitable functionalized [2.2]-and dithia[3.3]metacyclophane building blocks by using several multistep strategies. The C—C coupling of two cyclophanes according to the Hagihara method leads to alkynespacered double cyclophanes. These new preorganized, acyclic host compounds of the cyclophane-type react as molecular tweezers and can selectively “grasp” guest molecules and bind them strongly. X-ray analyses underline the syn conformations of the dithia[3.3]- and the anti conformation of the [2.2]metacyclophanes.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270426
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  • 123
    Digitale Medien
    Digitale Medien
    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A41 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270433
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  • 124
    Digitale Medien
    Digitale Medien
    Komplexe von Metallen der dritten Hauptgruppe mit [(en)2MIII(OH)2]-Liganden (M = Cr, Co) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 797-804 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Heteronuclear complexes ; Ligand [(en)2MIII(OH)2]+ (M = Cr, Co) ; Complexes of third group elements ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Complexes of Third Group Elements with [(en)2MIII(OH)2] Ligands (M = Cr, Co)Heteronuclear complexes are formed on reaction of cis-[(en)2-MIII(OH)(H2O)]2+ (M = Cr, Co; en = ethylenediamine) with A1III, GaIII, InIII, and T1III in aqueous solution. The following salts with tetranuclear cations have been isolated: [A1{(OH)2-Cr(en)2}3](S2O6)3 · 13 H2O (1), [A1{(OH)2Co(en)2}3](S2O6)3 · 5 H2O (2), [Ga{(OH)2Co(en)2}3](S2O6)3 · 5 H2O (3), [In{(OH)2-Cr(en)2}3](S2O6)3 · 6 H2O (5), and [In{(OH)2Co(en)2}3]-(ClO4)4Cl2 · 4 H2O (6). Furthermore, the dinuclear neutral complexes [InCl4{(OH)2Cr(en)2}] (4) and [TlCl4{(OH)2-Cr(en)2}] · 0.5 H2O (7) are prepared. X-ray analyses confirm that in all cases the [(en)2MIII(OH)2] groups act as bidentate ligands in the hydroxo-bridged heterometallic complexes.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270502
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  • 125
    Digitale Medien
    Digitale Medien
    Organische Synthesen mit Übergangsmetallkomplexen, 69. [2-(Acylamino)ethenyl]ketenimine aus [2-(Acylamino)ethenyl]carben-Komplexen sowie deren Ringschluß-Metathese zu Pyrrolen oder deren Elektrocyclisierung zu 1,4-DiaminonaphthalinenHerrn Prof. Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 717-724 
    Details
    ISSN: 0009-2940
    Schlagwort(e): [2-(Acylamino)ethenyl]carbene complexes ; Aminocarbene complexes of chromium and tungsten ; Ketene imines, 2-(acylamino)ethenyl ; Pyrroles, synthesis by ring-closing metathesis ; 1,4-Diaminonaphthalenes, synthesis by electrocyclization ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organic Syntheses via Transition Metal Complexes, 69[1].  -  2-(Acylamino)ethenyl Ketene Imines from [2-(Acylamino)ethenyl]carbene Complexes and their Ring-Closing Metathesis to Pyrroles or Electrocyclization to 1,4-DiaminonaphthalenesHerrn Prof. Helmut Werner zum 60. Geburtstag gewidmet.[2-(Acylamino)ethenyl]carbene complexes LnM = C(OEt) —CH=CPh—[N(COR)Ph] 5 [LnM = (CO)5Cr, (CO)5W; R = C6H5, pMeOC6H4, pNO2C6H4, OtBu] are obtained by N-acylation of [2-(amino)ethenyl]carbene complexes LnM=C (OEt)-CH=CPh(NHPh) (Z)-3 in 72-90% chemical yields with high stereoselectivity. The reaction of (Z) - or (E)-5 with two equivalents of isocyanides RNC 6 (R = cC6H11, tBu) at 20°C gives the isocyanide complexes LnM(RNC) 9 and the [2-(acylamino)ethenyl]ketene imines RN=C=C(OEt)—CH = CPh[N(COR)Ph] 8 (〉95% yields) with configurational retention at the C=C(N) bond. Thermolysis of (Z)-8 (20-80°C) provides an efficient route to pyrroles 11 (90-95%) by a ring-closing metathesis with elimination of isocyanates 10, while the thermolysis of (E)-8, e.g. (E)-8g, at 20°C leads to the formation of 1,4-diaminonaphthalenes, e.g. 12g (〉95% yield), by an electrocyclic ring closure.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270422
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  • 126
    Digitale Medien
    Digitale Medien
    Deformierte chirale [n]Metacyclophane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 759-765 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chirality ; Circular dichroism ; Conformational mobility ; Cyclophanes ; [n]Phanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Deformed Chiral [n]MetacyclophanesThe new dithiametacyclophane 3c and the thiaazametacyclophanes 6a, b are chiral, but do not contain chirality centres. They are obtained by cyclization of 1,3-propanedithiol (2), or of the thiaza precursors 5a, b, with the bis(bromomethyl) compounds 1, 4a, b. The dynamic behaviour of the aliphatic chains in 3c, and 6a, b (flipping/rotation) have been studied by dynamic NMR. X-ray analyses of 3c and 6a document the out-of-plane deformation of the boat-shaped benzene ring. The circular dichroism of enantiomer-enriched 3c is reported.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270427
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  • 127
    Digitale Medien
    Digitale Medien
    A Convenient One-Pot Preparation of Bis(nitroaryl) Tellurides Using a Tellurium-Copper Couple as the Telluration Reagent (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 783-785 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Tellurides, organo ; Substitution, aromatic ; Tellurium-copper couple ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Te-Cu couple generated in situ by the reaction of disodium telluride with copper(I) iodide in dry N-methyl-2-pyrrolidone has been found to be a convenient telluration reagent for some activated iodoarenes 1. Using this reagent system, we have prepared by a one-pot synthesis in satisfactory yields several bis(nitroaryl) tellurides 4, which are otherwise laborious to obtain.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270430
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  • 128
    Digitale Medien
    Digitale Medien
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270501
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  • 129
    Digitale Medien
    Digitale Medien
    Ring Cleavage of Benzofurans and Tetrahydrobenzofurans by m-Chloroperbenzoic Acid Epoxidation (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 941-946 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Epoxidation ; Benzofuran ; Benzofuran epoxide ; Quinone methide ; Benzofuran-2-one ; 2,4-Cyclohexadien-1-one, spiroepoxide ; cis-Ene dione ; Perester, β-hydroxy- ; 1,3-Benzodioxole ; Keto enol ester ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The oxidation of the benzofurans 1a-f (tetrahydrobenzofurans 1g, h) with excess m-CPBA is reported. The in situ generated, highly reactive benzofuran epoxides 2a-f and their quinone methides 3a-f (cis-ene diones 3g, h) afford the labile tautomeric peroxy esters 5 and 5′ by nucleophilic addition of the peroxy acid. On elimination of m-chlorobenzoic acid, the peroxy esters 5/5′ of the benzofuran derivatives 1a-f rearrange thermally to the keto esters 6 by C—C cleavage or to the spiro epoxides 7 by C—O cleavage. The latter undergo thermal isomerization to the 1,3-benzodioxoles 8 and Diels-Alder cycloaddition to the corresponding dimers 9. Independently, the keto esters 6 and the 1,3-dioxoles 8 were synthesized by thermolysis of the dioxetanes 11. The tautomeric m-CPBA adducts 5/5′ of the persistent ene diones 3g, h, derived from the tetrahydrobenzofuran derivatives 1g, h, rearrange as well to the spiro epoxides 7g, h. In contrast to the benzofuran derivatives 6a-f, the keto enol ester 6h suffers Baeyer-Villiger rearrangement with another molecule of m-CPBA to form the ene diester 10h.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270523
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  • 130
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    Digitale Medien
    2,6-Dicyano-1,5-dimethyl-4,8-diphenylsemibullvalene.  -  Synthesis, Structure and the Reactions with Triplet Oxygen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 921-932 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Bicyclo[3.3.0]octane, derivatives of ; Semibullvalene ; Tricyclo[3.3.0.02-8]octa-3,6-diene ; Cyclooctatetraenes, substituted ; Cyanohydrins, O-(trimethylsilyl)- ; Hydrogen fluoride  -  phosphorus oxychloride  -  pyridine, elimination of trimethylsilanol by ; Phenyl cuprate reagent, conjugate addition of ; Phase-transfer catalysis ; Chlorination by hexachloroethane  -  sodium hydroxide ; Cyclization by dehydrochlorination ; Endoperoxides by triplet oxygen ; 2 H-Pyran, derivative of ; Thermochromism ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Addition of trimethylsilyl cyanide to the diphenylbicyclo[3.3.0]octanedione 8c is catalyzed by the potassium cyanide/18-crown-6 complex and produces a mixture of the diastereomeric bis[O-(trimethylsilyl)cyanohydrins] endo- and exo-10c (3:2). The hydrogen fluoride - pyridine complex in phosphorus oxychloride as solvent and, subsequently, an excess of pyridine convert the mixture of diastereomers 10c into the unsaturated y,y′-diphenyldinitrile 11. This is converted into the red semibullvalene 4 in a single step by treatment with hexachloroethane and concentrated aqueous sodium hydroxide in the presence of tetrabutylammonium hydroxide as phase-transfer catalyst  -  Above 30°C, 4 isomerizes in solution to a mixture of the cyclooctatetraenes 12 and 13. While the red crystals of 4 are stable in the atmosphere, in the dark affording the endoperoxide 16 and the yellow 2H-pyran derivative 17 (7:1) which result from parallel reactions. Only at temperatures as high s 110°C, 16 slowly rearranges to 17 which reacts further to yield well-defined but still unknown products. The simultaneous formation of 16 and 17 at low temperatures is interpreted in terms of endo and exo attack, respectively, of triplet oxygen at the benzylic carbon atoms of the semibullvalene 4 or the isomeric bicyclic diradical 21.  -  The structures of the new compounds are based on spectroscopic evidence and X-ray diffraction analyses of 4, endo-10c, 11, 16, and 17. The semibullvalene 4 exists as a pair of rapidly rearranging degenerate valence tautomers in solution and in the crystal as well. In the solid state, 4 exhibits apparent C2 symmetry and equal atomic distances C2-C8 and C4-C6 (201.9 pm). Because true degeneracy is highly unlikely in the crystal, the equal distribution of two non-equivalent valence tautomers at room termperature results from a fortuitous cancelling of the ΔH° and TΔS° terms governing the equilibrium.  -  The red colour of 4 in the crystal and in solution is due to a maximum at 444 nm which disappears on cooling. Thus, 4 not only belongs to the family of thermochromic semibullvalenes and barbaralanes devoid of a long wavelength chromophor like 1, 6 and 14, but also shows the most intensive maximum at the longest wavelength observed so far.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270521
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  • 131
    Digitale Medien
    Digitale Medien
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270601
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  • 132
    Digitale Medien
    Digitale Medien
    Pyrazolylborat-Zinkkomplexe mit Medikament-Liganden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2381-2385 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Zinc complexes ; Pyrazolylborate ligands ; Drugs as ligands ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pyrazolylborate-Zinc Complexes with Drugs as LigandsThe model complexes for hydrolytic zinc enzymes L3Zn-OH with L3a = tris(3-tert-butyl-5-methylpyrazolyl)borate and L3b = tris(3-cumyl-5-methylpyrazolyl)borate (1a, b) were tested for their interaction with drugs. With acetazolamide (HAcm) the complex L3bZn-Acm (2b) is obtained which according to a structure determination contains the Acm ligand chelating by one azole and the sulfonamide nitrogen atoms. Furosemide (HFur) forms the two complexes L3Zn-Fur (3) which according to their spectra contain the furosemide anion as a monodentate carboxylate ligand. Aspirin (AcSalH) is saponified by both L3Zn-OH complexes yielding L3Zn-Sal (4). The structure determination of L3bZn-Sal (4b) has shown the salicylic acid to be bound as a monodentate carboxylate as well.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271207
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  • 133
    Digitale Medien
    Digitale Medien
    A Convenient Synthesis of Enantiomerically Pure Ethylene-Bridged Metallocene Complexes Bearing Fluorenyl- and Octahydrofluorenyl Ligands[1] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2417-2419 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Epoxides, optically pure ; Zirconocenes, enantiomerically pure ; Octahydrofluorenyl ligands ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ring opening of (R)-(-)-epoxystyrene (1) with fluorenyllithium leads to the optically active alcohol 2 in high yield. Derivatization of 2 to the trifluoromethanesulfonate 4 and subsequent reaction with one equivalent of fluorenyllithium gives the ligand precursor (1S)-1,2-bis(9-fluorenyl)-1-phenylethane (5), which is used for the synthesis of [(1R)-1,2-bis(η5-9-fluorenyl)-1-phenylethane]ZrCl2 (6).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271212
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  • 134
    Digitale Medien
    Digitale Medien
    Regioselective Protonation of Allyllithium CompoundsDedicated to Prof. W. Tochtermann on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2431-2433 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Protonation, regioselective ; Allyllithium compound ; Allyl anion ; General acid ; Regioselectivity ; Aging ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: By varying the general acid, the regioselectivity of the protonation of (triphenylsilyl)allyllithium (1) in diethyl ether in the presence of HMPT can be changed from 9:1 to 1:9 at room temperature. When other aprotic solvents are used, the nature of the lithium salt changes, and the selectivity decreases. The regioselectivity of the protonation of the dithio-stabilized allyllithium 4 by water is highly dependent on the age of the allyllithium solution with α/γ ratios varying from 2.7:1 to 1:3.5.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271214
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  • 135
    Digitale Medien
    Digitale Medien
    Organic Syntheses via Transition Metal Complexes, 74[1] Novel Phosphonium Allenide and 2-Phosphanylethenyl Carbene Chromium and Tungsten Complexes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2475-2482 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Vinylcarbene complexes ; Chromium complexes ; Tungsten complexes ; Phosphorus ylide complexes ; Alkynylcarbene complexes ; Allene complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alkynylcarbene complexes (CO)5M≡C(OEt)-C≡C—R 1 (M = Cr, W; R = Ph, tBu, SiMe3) readily add tertiary phosphanes PPhR2′ 4 (R′ = Ph, Me) to form stable zwitterionic phosphonium allenide complexes (CO)5M--C(OEt) = C≡C(R)-P+PhR2′ 5. Complex 5a (M = Cr, R = R′ = Ph) was characterized by X-ray diffraction. The addition of secondary phosphanes PHR2 6 to 1 affords red (2-phosphanyl ethenyl)-carbene complexes (CO)5M≡C(OEt)-CH≡C(R)-PR2 (E)-8 (R = tBu, cC6H11, Ph) in 34-89% isolated yields. Dinuclear complexes (CO)5M≡C(OEt)-CH≡C(R)-P(R2)M(CO)5 (E)-9 are obtained as byproducts. Compounds (E)-8b (M = Cr, R = cC6H11) and (E)-9i (M = Cr, R = Ph) were characterized by X-ray analyses.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271218
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  • 136
    Digitale Medien
    Digitale Medien
    How Electrophilic are Ferrocenylmethyl Cations? Kinetics of their Reactions with π Nucleophiles and Hydride DonorsDedicated to Professor Dr. W. Tochtermann on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2493-2498 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Electrophilicity ; Ferrocenylmethylium ions ; Kinetics ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Second-order rate constants for the reactions of the ferrocenylmethylium ions 2a - e with silyl enol ethers, allylsilanes, allylstannanes, and hydride donors have been determined photometrically and conductometrically in dichloromethane. The ferrocenylmethylium ions 2a - d (fc-CHR+, R = H, Me, Ph, An) are slightly stronger electrophiles than the tropylium ion, and their electrophilic reactivities depend only slightly on the nature of R. The bis(ferrocenyl)methylium ion 2e is a considerably weaker electrophile, comparable to the tricarbonyl(cyclohexadienyl)iron cation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271221
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  • 137
    Digitale Medien
    Digitale Medien
    Stereoselective Synthesis of Alcohols, XLVII[1] Application of Chiral Z-Pentenylboronates to the Synthesis of Erythronolide Building Blocks (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2511-2518 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Allylboration, stereoselective ; Erythronolide building blocks ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The chiral pentenylboronate 3 was the key reagent in the stereoselective construction of two erythronolide building blocks 6 and 7. Addition of 3 to achiral aldehydes furnished homoallylic alcohols 21 and 26 with 〉98% e.e. Addition of 3 to chiral aldehydes 8 or 11 generated homoallylic alcohols with 〉95% d.e. In the mismatched case of addition to the aldehyde 29 diastereoselectivity reached merely 80%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271224
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  • 138
    Digitale Medien
    Digitale Medien
    (η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt - ein selektiver Katalysator für die Pyridinsynthese (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2535-2537 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cobalt complexes, (η3-allyl)(η5-pentamethylcyclopentadienyl)- ; Pyridine synthesis ; Catalytic activity ; Chemoselectivity ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt - a Selective Catalyst for the Pyridine Synthesis(η3-Allyl)(η5-pentamethylcyclopentadienyl)cobalt (1) catalyses the synthesis of various pyridines from alkynes and nitriles under mild conditions. Only small amounts of benzenes are formed in this selective reaction.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271228
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  • 139
    Digitale Medien
    Digitale Medien
    Synthese und Eigenschaften von Makrocyclen aus Resorcinen sowie von entsprechenden Derivaten und Wirt-Gast-Komplexen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2455-2469 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Resorcinarenes, macrocyclic ; Conformations ; Metal complexes ; Host-guest complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and Properties of Macrocycles from Resorcinol, Corresponding Derivatives and Host-Guest ComplexesStructural variations of the metacyclophanes obtained from the condensation of resorcinol with aldehydes RCHO are described, mostly based on the stereoisomer with all R in cis configuration. The basic tetraphenolate (with R = CH3, 1a) shows a cone-conformation as evident e.g. from vicinal 13C-C-C-1H coupling constants. Substituents R′ in the 2-position of the phenyl rings at the upper rim of the macro-cycle are either introduced with the resorcinol derivative used (R′ = CH3, COOH), or by Mannich reactions after cyclization (R′ = CH2NR″2), which partially lead to intermediate oxacine formation. Acid-base properties are evaluated with potentiometric and NMR-shift titrations. Mannich products from amino acids such as proline, which are formed without racemization, show no pK differences for the groups at the four equivalent phenyl rings, but three distinct pK values for the deprotonation of OH, COOH, and +NH3 substituents; the pK of the latter is two units lower than in proline itself as it is involved in hydrogen bridging. Complexation constants K of such derivatives with Fe3+, Cu2+, and Zn2+ show the expected increase with metal ion acidity; they are increased by a power of 5 in comparison to proline. Complexation constants and complexation-induced NMR shifts (CIS values) are determined for 51 complexes, with positively charged organic guest molecules for the basic tetraphenolate skeleton as well as for the aminomethylation derivatives. A temperature dependence study shows that the corresponding equilibrium is driven by ΔH with negligible ΔS contributions. No chiral discrimation is observed upon complexation of e.g. carnitine with the optically active amino acid derivatives. This is in line with CIS and K values obtained with several complexes showing an orientation of the NR″2 groups away from the cavity. The COOH substituents R′ form strong hydrogen bonds with the adjacent phenolic groups, leading to alternating pseudo-eq and -ax positions of the phenyl rings. Their interconversion barrier, determined by NMR spectroscopy, is 72 kJ mol-1; they bind mono- and bis-ammonium ions as function of distance matching. The presence of lipophilic substituents (R = phenyl, benzyl, biphenyl, n-hexyl, n-undecyl) at the bottom of the macrocycle furnishes a second binding center which allows to complex e.g. diethyl ether in water. Coordination of zinc to the proline derivative still allows co-complexation of choline acetate, the hydrolysis of which is not inhibited anymore as it is by the zinc-free macrocycle.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271216
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  • 140
    Digitale Medien
    Digitale Medien
    Coordination Polymers, IX[1] Synthesis and Crystal Structure of a 1D-Sodium Coordination Polymer: [NaL4(PMDETA)]∞ (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2489-2492 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Tetrazoles ; Coordination polymer, 1D ; Self-assembly ; Sodium complex ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of sodium hydride with the tridentate tetrazole ligand 10 (HL4) and pentamethyldiethylenetriamine (PMDETA) in toluene yields by self-assembly in the solid-state the well-ordered 1D-coordination polymer [NaL4(PMDETA)]∞, (11). The structure of 11 was established by single-crystal X-ray diffraction. The generation of the 1D-polymer 11 is understandable if intermediate formation of coordinatively unsaturated, neutral sodium building blocks [NaL4(PMDETA)] (12) is assumed. Such a self-complementary monomer 12 acts in a monodentate fashion via its CN group, leading to linkage of monomers and to coordinative saturation at the sodium centre of 12. The sodium ions of the resulting polymeric chains of 11 are coordinated in a distorted octahedral manner. These results indicate that sodium derivatives of CN-containing ligands may be tuned as to their dimensionality, especially so since Na+ can cope with coordination numbers of 4, 5, or 6, such tuning could be probed initially by provision of further available functionalities within the anionic ligand and/or by provision of Lewis base donors of varying denticity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271220
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  • 141
    Digitale Medien
    Digitale Medien
    Reactivity Tuning by Ligand Effects: Gas-Phase Reactions of Fe(C6H6)O+ versus “Bare” FeO+ (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2499-2503 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Bond activation ; Oxygen atom transfer ; Iron oxenoid chemistry ; Rate constants ; Ion cyclotron resonance mass spectrometry ; Ligand effects ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The presence of a benzene ligand in Fe(C6H6)O+ (1) has a profound effect on the gas-phase reactivity of FeO+. While the latter oxide is known to act as an efficient C-H/C-C bond-activation reagent, the ligated species 1 is entirely unreactive in that respect. However, 1 serves as an excellent reagent for transferring oxygen to various olefins. In addition, it is demonstrated that the ligand substitution Fe-(C6H6)O+ + X → Fe(X)O+ + 6H6) follows two principally different pathways. For X = C6D6 and C5H5N the traditional direct substitution process with attack at the metal centre is operative. However, for X = olefins it is argued that the olefin will not initially attack the metal center; rather, the reaction commences by coordinating the olefin X to the oxygen atom of Fe6H6)O+. The resulting intermediate (6H6)Fe(OX)+ will then fall apart either to separated Fe(OX)+/6H6) or to Fe(6H6)+/OX, thus bringing about an epoxidation of the olefin rather than ketone formation.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271222
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  • 142
    Digitale Medien
    Digitale Medien
    Heterogene Gasphasen-Eliminierungen mit dem System Magnesiumoxid/Kalium (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2531-2533 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Catalysis, heterogeneous ; Potassium ; Dehydrogenation ; Debromination ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Heterogeneous Gasphase Eliminations with the System Magnesium Oxide/PotassiumAfter evaporation of potassium and condensation on a magnesium oxide surface a highly reactive blue reagent is formed which is active in dehydrogenation reactions. 1,4-Cyclo-hexadiene (1) and 1,3-cyclohexadiene (2) can effectively be converted into benzene at room temperature while dehydrogenation of cyclohexene 3 needs temperatures higher than 200°C. The reaction mechanism is discussed. Debrominations with MgO/K can likewise be carried out under rather mild conditions.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271227
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  • 143
    Digitale Medien
    Digitale Medien
    Photochemische und thermische Erzeugung von Thiocarbonylyliden aus 2,5-Dihydro-1,3,4-thiadiazolenIn vorläufiger Form von G. Mloston präsentiert auf dem 16. Internat. Symposium über die Organische Chemie des Schwefels, Merseburg, 10.-15. Juli 1994, Abstract Book, p. 2.46. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2527-2530 
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    ISSN: 0009-2940
    Schlagwort(e): Matrix isolation ; Photochemistry ; Flash pyrolysis ; Ylides ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photochemical and Thermal Generation of Thiocarbonyl Ylides from 2,5-Dihydro-1,3,4-thiadiazoles[*]Thermolysis of thiadiazolines 2a-c yields the corresponding thiiranes 5a-c exclusively. In contrast matrix photolysis in an organic glass at 77 K or in solid Ar at 10 K allows the detection of the thiocarbonyl ylides 3a-c, which are characterized by intense UV maxima at λ ≈ 350 nm. The thiocarbonyl ylides are formed in a stepwise manner and not directly from the thiadiazolines by a simple elimination of N2. In the first step a fragmentation into the thioketones 6a-c and diazomethane occurs, followed by the generation of methylene (8) from diazomethane (7). Addition of methylene to the thioketones 6a-c finally leads to the ylides 3a-c.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271226
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  • 144
    Digitale Medien
    Digitale Medien
    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A-91 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270835
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  • 145
    Digitale Medien
    Digitale Medien
    Zur Addition von Alkyldichlorboranen an Bis(η5-cyclopentadienyl)dihydridowolfram (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1613-1614 
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    ISSN: 0009-2940
    Schlagwort(e): Tungsten, bis(η5-cyclopentadienyl)dihydrido- ; Boranes, alkylchloro ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: On the Addition of Alkyldichloroboranes to Bis(η5-cyclopentadienyl)dihydridotungstenReaction of basic [Cp2WH2] (1) with the Lewis acids iPrBCl2 and tBuBCl2 does not lead to adducts of the type [Cp2WH2 (RBCl2)] [R = iPr, tBu]. The zwitterions [CpWH3(η5-C5H4BRCl2)] (R = iPr, 2a; tBu, 2b) having an exocyclic boron substituent were isolated instead in 60% yield. The molecular structure of 2b crystallizing in the space group P21/n is proved by X-ray structure determination.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270910
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  • 146
    Digitale Medien
    Digitale Medien
    Chemistry of Diborane(4) Derivatives: Mixed Tetraaminodiboranes(4) and Additions of Diborane(4) Derivatives to an Amino-imino-borane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1605-1611 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Diborane(4), tetraamino-, derivatives ; Diborane(4), tetrapiperidino ; 1,2,3,6-Diazadiborinane derivatives ; Haloboration ; Methoxyboration ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several transamination reactions of B2(NMe2)4 (1a) with secondary amines have led to mixed tetraaminodiborane(4) compounds B2(NMe2)4 - n(NR2)n (2-4), and B2(NC5H10)4 (1d) has been characterized by an X-ray structure analysis which reveals the presence of a rather long B-B bond (1.75 Å). However, tetraaminodiboranes(4) of type R2N(Me2N)B-B(NMe2)NR2 are more readily accessible from LiNR2 and B2(NMe2)2Cl2. Similarly, amination of B2(NMe2)2Cl2 with N,N'-dimethylethylenediamine (7) yields B-[bis(dimethyl-amino)boryl]-N,N'-dimethyl-1,3,2-diazaborolidine (8), while reactions with Li(Me)N-CH2-CH2-N(Me)Li (9) lead also to 2,3-bis(dimethylamino)-1,4-dimethyl-1,4,2,3-diazadiborinane (10) as the kinetically controlled product. This is further substantiated by the reaction of the B2(NMe2)2Br2 with 9 which gives exclusively the corresponding 1,4,2,3-diazadiborinane 11. Diborane(4) dihalides B2(NMe2)2X2 (X = Cl, Br) react only in a 1:1 ratio with tmp-B=N-CMe3 (13) leading to 14a, b. However, both a 1:1 and a 1:2 methoxyboration of 13 has been observed with B2(OMe)4 with formation of 15 and 16.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270909
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  • 147
    Digitale Medien
    Digitale Medien
    Synthesis and Structure of the New α-Aminosilanolate [LiOSiMe2(NMe2)]6 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1619-1620 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Silanolate ; Aminosilanolate ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Lithium (dimethylamino)dimethylsilanolate (1) is obtained from trimeric dimethylsiloxane and lithium dimethylamide in quantitative yield. In the crystal 1 is a hexamer [LiOSiMe2(NMe2)]6 with crystallograpic C3i (S6, 3) symmetry. The molecule of 1 consists of a hexagonal prismatic (LiO)6 core and an N,O-chelating anion.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270912
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  • 148
    Digitale Medien
    Digitale Medien
    Twofold Deprotonated Citric Acid as a Bidentate Ligand of Pentacoordinate Silicon: Synthesis and Structural Characterization of the Zwitterionic λ5Si-Spirosilicate Bis[citrato(2-)-O3,O4][(dimethylammonio)methyl]silicate Hydrate (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1615-1617 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Silicon, pentacoordinate ; λ5Si-Spirosilicate, zwitterionic ; Citrato(2-)-O3,O4 ligand ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The zwitterionic λ5Si-spirosilicate bis[citrato(2-)-O3,O4][(dimethylammonio)methyl]silicate (4) was synthesized by reaction of (MeO)3SiCH2NMe2 (3) with citric acid (molar ratio 1:2) in acetonitrile at room temperature and isolated, after crystallization from water, as the hydrate 4 . H2O (yield 81%). The crystal structure of 4 . H2O was studied by single-crystal X-ray diffraction. The alcoxide oxygen atoms and central carboxylate oxygen atoms of two citrato(2-) ligands and one carbon atom coordinate to the silicon atom of 4 . H2O. The coordination polyhedron around the pentacoordinate silicon atom (SiO4C framework) can be described as a distorted trigonal bipyramid, the two carboxylate oxygen atoms occupying the axial sites. The λ5Si-silicon(IV) complex 4 also exists in solution (DMSO, H2O).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270911
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  • 149
    Digitale Medien
    Digitale Medien
    Metalloragnische Verbindungen der Lanthanoide, 90[1] [(tert-Butylcyclopentadienyl)dimethyl(tetramethylcyclopentadienyl)silan]-Komplexe von Lanthan, Neodym und Lutetium (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2363-2367 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cyclopentadienyl complexes ; Lanthanum compounds ; Neodymium compounds ; Lutetium compounds ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organometallic Compounds of the Lanthanides, 90[1]. - [(tert-Butylcyclopentadienyl)dimethyl-(tetramethylcyclopentadienyl)silane] Complexes of Lanthanum, Neodymium, and Lutetium[(tBuC5H3)SiMe2(C5Me4)]Li2 (1) reacts with LnCl3 (Ln = La, Lu) in THF to yield [(tBuC5H3)SiMe2(C5Me4)]Ln(μ-Cl)2Li-(OEt2)2 [Ln = La (3a), Lu (3c)]. The reactions of LnCl3 (Ln = La, Nd) with [(tBuC5H3)SiMe2(C5Me4)]Na2 (2) and (C5Me4H)Na in THF result in the formation of the chiral tris(cyclopentadienyl) complexes [(tBuC5H3)SiMe2(C5Me4)]Ln-(C5Me4H)(THF) [Ln = La (4a), Nd (4b)]. The 1H- and 13CNMR and mass spectra of the new compounds as well as the X-ray crystal structure of 4a are discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271204
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  • 150
    Digitale Medien
    Digitale Medien
    Metallorganische Verbindungen der Lanthanoide, 91[1] Carben-Addukte des zweiwertigen Samariums und Ytterbiums (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2369-2372 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cyclopentadienyl complexes ; Carbene complexes ; Samarium(II) compounds ; Ytterbium(II) compounds ; Lanthanides, organo- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organometallic Compounds of the Lanthanides, 91[1]. - Carbene Complexes of Divalent Samarium and Ytterbium(Imidazol-2-ylidene)lanthanide adducts (C5Me4Et)2Sm-CN-(iPr)CMe=CMeN(iPr) (5b), (C5Me5)2Yb-CN(Me)CMe=CMeN(Me) (6a), (C5Me5)2Yb-CN(iPr)CMe=CMeN(iPr) (6b), and (C5H3tBu2)2Yb-CN(Me)CMe=CMeN(Me) (7a) are obtained from 1,3,4,5-tetramethyl-imidazol-2-ylidene (4a) or 1,4-diisopropyl-2,3-dimethylimidazol-2-ylidene (4b) and (C5Me4Et)2Sm(THF) (1), (C5Me5)2Yb(THF) (2), or (C5H3-tBu2)2Yb(THF) (3). The molecular structure of the ytterbium carbene complex 7a has been determined by X-ray diffraction.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941271205
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  • 151
    Digitale Medien
    Digitale Medien
    Titan-, Zirconium- und Hafniumkomplexe mit 1,2,4-Tri-tert-butylcyclopentadienyl-LigandenHerrn Professor Otto J. Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 3-9 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1,2,4-Tri-tert-butylcyclopentadienyl complexes ; Group IV metallocene derivatives ; Titanocene dichloride, alkylated ; Zirconocene dichloride, alkylated ; (Cyclopentadienyl)hafnium trichloride ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Titanium-, Zirconium- and Hafnium Complexes with 1,2,4-Tri-tert-butylcyclopentadienyl LigandsLithium salts of easily available 1,3,5-tri-tert-butylcyclopentadiene and 1,2,3,4,5-pentaethylcyclopentadiene are used to synthesize the trichlorides [Cp‴MCl3] [Cp‴ = C5H2tBu3-1,2,4; M = Zr (1), Hf (2), Ti (3)] and [(Et5C5)ZrCl3] (4). Complex 1 is converted into the mixed zirconocene dichlorides [Cp‴CpZrCl2] (5), [Cp‴Cp-ZrCl2] (6), [Cp‴Cp″ZrCl2] (7), [Cp‴Cp4ZrCl2] (9) (Cp = C5H5, Cp* = C5Me5, Cp″ = C5H3tBu2-1,3, Cp4 = C5iPr4H) and into the benzyl complexes [Cp‴Zr(PhCH2)2Cl] (10) and [Cp‴Zr(PhCH2)3] (11). Variable-temperature 1H-NMR spectra of 6-9 (8 is the Ti analogue of 7) indicated hindered oscillation of the Cp‴ ligand with ΔG≠ values between ≤8 kcal/mol (7, 9) and 13.2 kcal/mol (6). X-ray structural analyses of complexes 7 and 9 reveal strong distortions owing to extreme steric congestion.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270102
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  • 152
    Digitale Medien
    Digitale Medien
    Functionalized, 1,1-Ethenedithiolates as Ligands, III. Palladium(II) and Platinum(II) Complexes with Ferrocenyl-Substituted 1,1-Ethenedithiolate Ligands. Crystal Structure Analyses of cis-(Ph3P)2M[S2C=CH—C(O)-(η5-C5H4)Fe(η5-C5H5)] (M = Pd, Pt)Dedicated to Professor Dr. Dr. h. c. mult. E. O. Fischer on the occasion of his 75th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 23-26 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Ferrocene derivatives ; 1,1-Ethenedithiolate complexes ; Group 10 metal complexes ; Heterodimetallic compounds ; Heterotrimetallic compounds ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ferrocenyl-substituted mono- (3) and 1,1′-bis-dithiocarboxylic acids (4) have been prepared. These acids react with L2MCl2 (M = Pd, Pt; L = PEt3, PPh3, and 1/2 dppe) in the presence of sodium acetate to give the cis heterodi- and heterotrimetallic complexes cis-L2M[S2C=CH—C(O)-(η5-C5H4)Fe(η5-C5H5)] (5a: M = Pd, L = PPh3; 5b: M = Pt, L = PPh3; 5c: M = Pt, L = 1/2 dppe) and [cis-L2MS2C = CH—C(O)-(η5—C5H4)]2Fe (6a: M = Pd, L = PPh3; 6b: M = Pt, L = PEt3; 6c: M = Pt, L = PPh3; 6d: M = Pt, L = 1/2 dppe). The structures of 5a and 5b have been determined by single-crystal X-ray diffraction.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270105
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  • 153
    Digitale Medien
    Digitale Medien
    η3-Allyl- und η3-Benzyl-Rhodiumkomplexe: Synthese, Strukturdynamik und Reaktionen mit Carbonsäuren (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 27-38 
    Details
    ISSN: 0009-2940
    Schlagwort(e): η3-Allylrhodium complexes, preparation with Grignard reagents ; η3-Benzylrhodium complexes, antara- and suprafacial rearrangements in solution ; Unsymmetrical η3-benzyl-to-metal bonding in the solid state ; Rhodium, η1-benzyl(carbonyl) compound ; Rhodium, monomeric square-planar η2-carboxylato complexes ; η3-Allyl(η1-carboxylato)hydridometal intermediates, formation by oxidative addition ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: η3-Allyl and η3-Benzyl Rhodium Complexes: Synthesis, Structure Dynamic, and Reactions with Carboxylic AcidsThe (η3-allyl)rhodium complexes [Rh(η3-2-RC3H4)(PiPr3)2] (3-5) have been prepared in 70-90% yield from the in situ generated chlororhodium precursor [RhCl(PiPr3)2] (2) and 2-RC3H4MgX. On a similar route, the corresponding ethene(phosphane) derivative [Rh(η3-2-MeC3H4)(PiPr3)] (9) has been obtained. Compound 9 smoothly reacts with PiPr3 and PMe3 to give 4 (R = Me) and [Rh(η3-2-MeC3H4)(PMe3)-(PiPr3)] (10), respectively. In contrast to the η3-allyl complexes which are configurationally stable, the η3-benzyl analogues [Rh(η3-CH2C6H4R) (PiPr3)2] (11, 12), prepared from 2 and 4-RC6H4CH2MgCl, are highly fluctional in solution. At room temperature, an antarafacial (π-δ-π) as well as a suprafacial rearrangement occurs, the first one of which is frozen out at 263 K. On cooling to 193 K, the faster process (equally designated as a metallotropic shift) is also slowed down, and the rigid structure of 11 and 12 is observed. The ΔG* values for the antara and suprafacial rearrangements of 11 and 12 which have been determined from the 1H- and 31P-NMR spectra at variable temperature are 60.0 ± 1.5 and 39.5 ± 1.0 kJ/mol, respectively. The η3-benzyl compound 11 reacts even at -78°C with CO to give the monocarbonylrhodium(I) complex trans-[Rh(η1-CH2C6H5)(CO)(PiPr3)2] (13). Treatment of 3,4, or 11 with RCO2H (R = CF3, CH3, C6H5, C6H4-4-OMe, C6H4-4-NO2) affords the monomeric η2-carboxylatorhodium(I) compounds [Rh(η2-O2CR) (PiPr3)2] (14-18) almost quantitatively. If the reaction of 3 or 4 with CF3CO2H is performed at -20°C in pentane, the octahedral (η3-allyl)hydrido complexes [Rh(η3-2-RC3H4)(H)(η1-O2CCF3)(PiPr3)2] (19, 20) are isolated. The crystal structures of 12 (at 223 K) and of 15 (at 298 K) have been determined by X-ray diffraction studies. They confirm that the η3-benzyl ligand is highly unsymmetrically and the acetato ligand completely symmetrically bound to the [Rh(PiPr3)2] unit.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270106
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  • 154
    Digitale Medien
    Digitale Medien
    Beiträge zur Chemie des Bors, 221. Kinetische und thermodynamische Produktkontrolle bei der Addition von HX-Verbindungen an ein Amino-phosphanylimino-boran R2N—B—N—PR2′Herrn Prof. Dr. O. J Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 81-85 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Boranes ; Aminoboranes ; Phosphanyliminoboranes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Contributions to the Chemistry of Boron, 221[1].  -  Kinetic and Thermodynamic Product Control in the Addition of HX Compounds to an Amino Phosphanylimino Borane R2N—B≡N—PR2′The reaction of equimolar amounts of HI with tmp=B≡N—PtBu2 (3) (tmp = 2,2,6,6-tetramethylpiperidino group) in an unpolar solvent yields the phosphonium salt [tmp-B=N—PHtBu2]I (4). No such well-defined reaction was observed with triflic or tetrafluoroboric acid. In contrast, HCl reacts with 3 to produce a mixture of tmp-B(Cl)-NH-PtBu2 (5) and tmp - B(Cl) - N=PHtBu2 (6). On heating or on standing at ambient temperature the unique proton of 5 migrates from the N to the P atom with formation of 6, which, therefore, is thermodynamically more stable than 5.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270112
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  • 155
    Digitale Medien
    Digitale Medien
    Synthesen, Struktur und Eigenschaften von 1,2,5-PhosphadiborolanenHerrn Professor Otto J. Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 329-331 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1,2,5-Phosphadiborolanes ; 1,2,5-Thiadiborolanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Syntheses, Structure and Properties of 1,2,5-PhosphadiborolanesReactions of (Z)-1,2-bis[chloro(diisopropylamino)boryl]ethane with Li2PC6H5 and of 1,2-bis[chloro(diisopropylamino)boryl]-1,2-diisopropylideneethane with [LiPh2·dme] yield the 1,2,5-phosphadiborolanes 1 and 2, respectively. The compounds are characterized by 1H-, 11B-, 13C-, and 31P-NMR spectroscopy as well as an X-ray structure analysis of 2. Low-temperature 1H-NMR studies show that the inversion barrier at P is distinctly lower than that of related unsaturated compounds. This might be the result of a favorable B—P-π interaction in the transition state of the inversion at the phosphorus atom. Reaction of 1 with S8 or CS2 leads to the 1,2,5-thiadiborolane 3.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270208
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  • 156
    Digitale Medien
    Digitale Medien
    Strukturen und Moleküleigenschaften sterisch überfüllter Moleküle, 43. Triisopropylammonium-chlorid: Einkristallstruktur und Berechnungen zur Protonierung des p-Typ-Stickstoff-Elektronenpaares (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 347-351 
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    ISSN: 0009-2940
    Schlagwort(e): Sterically overcrowded trialkylammonium salt ; Single-crystal structure ; Protonation-energy hypersurface calculations ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Structures and Molecular Properties of Sterically Overcrowded Molecules 43[1].  -  Triisopropylammonium Chloride: Single-Crystal Structure and Calculations Concerning the Protonation of the p-Type Nitrogen Electron Pair[2]The protonation of triisopropylamine, which contains an almost planar NC3 skeleton of C3 symmetry and, therefore, a p-type N electron pair, with HCl in methanol causes severe structural perturbation due to extreme steric overcrowdedness: the single-crystal structure determination (orthorhombic Pbca, Z = 8) proves that the molecular symmetry is reduced to C5 by the rotation of one isopropyl group around its CN axis by almost 90° and the decrease of the angles CNC from 119° each to 115, 115 and 111°, respectively. The Cl⊖⃛(H)N hydrogen bond distance of 315 pm is presumably slightly increased by steric overlap of the van der Waals radii of Cl⊖ and one of the three adjacent methyl groups. The protonation of the p-type lone pair of triisopropylamine including the pyramidalization of the nitrogen centre and the twist of one isopropyl group can be simulated by a one-dimensional energy hypersurface calculation, if H⊕ attack outside the C3 axis is assumed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270211
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  • 157
    Digitale Medien
    Digitale Medien
    Elektrophile Additionen an das Bicyclo[1.1.0]butan-System von Tricyclo[4.1.0.02,7]heptan-Derivaten: Halogen-ElektrophileHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 381-391 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Norpinanes, preparation ; Carbocations, classical and nonclassical ; Neighbouring group participation ; Halonium ions ; Migratory aptitudes in carbocations ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electrophilic Additions to the Bicyclo[1.1.0]butane System of Tricyclo[4.1.0.02,7]heptane Derivatives: Halogen ElectrophilesThe known reactions of 8,8-dibromotetracyclo[5.1.0.02,4.03,5]octane (3a) and homobenzvalene (7) with pyridinium bromide perbromide and iodine, respectively, were carried out in the presence of tetra-n-butylammonium chloride. The formation of the chloro-substituted norpinane derivatives 6a and 9 is evidence for cationic intermediates. The same mechanism is operative in the reaction of pyridinium bromide perbromide with the dichlorotetracyclooctane 3b, which was prepared from 7 and dichlorocarbene. On exposure of tricyclo[4.1.0.02,7]heptane (1) to N-bromosuccinimide in acetone/water/triethylamine, the bromonorpinanol 22, the bromonorcaranols 23, and cyclohex-1-ene-1-carboxaldehyde (24) were obtained. On the basis of the steric course and thermodynamic considerations, the cationic intermediates generated in the above reactions by attack of the electrophiles at the bicyclobutane systems are assigned the halonium ion structure 38 and the nonclassical structures 34 and 35, respectively. Elemental bromine and iodine converted the phenyltricycloheptane 10 into the respective diastereomeric norpinanes 11 and 12, which were transformed smoothly into the diastereomeric methyl ethers 13 and 14 by treatment with sodium methoxide in methanol. The reactions of 10 with pyridinium bromide perbromide in pyridine, cyanogen bromide in the presence of aluminium trichloride, and N-bromosuccinimide in acetone/water gave rise to norpinane derivatives, i.e. the pyridinium salt 15, the nitrile 16, and the alcohol 18, respectively. In the case of cyanogen iodide in acetonitrile, the solvent participated in the process to yield the 2-(norpinylimino)propionitriles 17. Corresponding to the configurations of the products, the attack of a halogen electrophile at 10 leads to classical 6-phenyl-6-norpinyl cations 41, which may be approached by nucleophiles from the two possible faces. As origin for the low tendency of the cations 33-35 and 41 to rearrange to norcaryl cations, the electronegativity of the halogen atoms is suggested. The reduced migratory aptitude of a CHHal relative to a CH2 group results from its electron deficiency and from the decreased stability of 7-halo-2-norcaryl relative to the parent 2-norcaryl cations. The chlorophenyltricycloheptane 25 was prepared from 10 and treated with aqueous sulfuric acid to give the norpinanol 27. Formed by protonation of the bicyclobutane system of 25, the cationic precursor of 27 shows a behaviour similar to that of cations 41.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270215
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  • 158
    Digitale Medien
    Digitale Medien
    Thermal and Photochemical Rearrangement of 3-Substituted 2-Methylbenzofuran Epoxides and Their Valence-Isomeric Quinone Methides (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 433-436 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Epoxidation ; Dioxirane, dimethyl- ; Benzofurans, 2-methyl- ; Benzofuran epoxides ; Quinone methides ; Photoisomerization ; Chromenes ; 3-Benzofuranones ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The dimethyldioxirane oxidation of the 3-substituted 2-methylbenzofurans 1 [1a: 3(E)-styryl, 1b: 3-acetoxy, 1c: 3-(tert-butyldimethylsilyloxy)] is reported. Only quinone methide 3a, none of the benzofuran epoxides 2a-c, could be detected by 1H- and 13C-NMR spectroscopy at low temperature (-30°C), which on photoisomerization led to chromene 7a. The benzofuran-3-ones 5b, c and the α-diketone 6c are presumably formed by thermal isomerization of the transient benzofuran epoxides 2b, c and quinone methide 3c.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270220
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  • 159
    Digitale Medien
    Digitale Medien
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270301
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  • 160
    Digitale Medien
    Digitale Medien
    On the Reaction of 1-Aza-2-azoniaallene Salts with Isocyanates (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 947-953 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1-Aza-2-azoniaallene cations ; Isocyanates ; 4,5-Dihydro-5-oxo-1,2,4-triazolium salts ; Cinnolinium salts ; Cycloadditions ; Calculations, AM1 ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1-Aza-2-azoniaallene salts 3, prepared in situ from geminal chloroalkylazo compounds 2 with Lewis acids, react with isocyanates 4 to give 4,5-dihydro-5-oxo-3H-1,2,4-triazolium salts 6 and 4,5-dihydro-5-oxo-1H-1,2,4-triazolium salts 7, respectively. The intramolecular cyclization of 3u opens a new route to cinnolinium salts 11. Allenes 3 react with isobutene to give pyrazolium salts 8. According to AM1 calculations the cycloadditions of 3 to isocyanates proceed in two steps via acylium salts 5 as intermediates. Mechanistically, the rearrangements 6 → 7 resemble Wagner-Meerwein rearrangements rather than pericyclic [1,5]-sigmatropic shifts.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270524
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  • 161
    Digitale Medien
    Digitale Medien
    Photoenolization of 4-Naphthoyl[2.2]paracyclophanes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 965-966 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cyclophanes ; Photochemistry ; Triplet states ; Enolization ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: When ethanolic solutions of 4-(1-naphthoyl)[2.2]paracyclophane (3) and 4-(2-naphthoyl)[2.2]paracyclophane (4) are subjected to UV irradiation at low temperature, 1,5-hydrogen migration of the 2-H bridge proton to the carbonyl group takes place, leading to the enol of type 2. In the context of mechanistic considerations the triplet spectroscopic properties of 3 and 4 are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270527
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  • 162
    Digitale Medien
    Digitale Medien
    Transition Metal Chemistry of Main Group Hydrazides, VI. New Directed Synthetic Strategies to Functionalized Heterocyclic Phosphorus(III) Hydrazides. First Examples of Crystal and Molecular Structures of [RPN(Me)N(H)]2 (R = Et, Ph, and tBu) (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 979-984 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cyclophosphahydrazides ; Dinitrogen-bridged ; Conformation ; Chair and Boat forms ; Dinuclear Mo(0) complexes ; 1,2,4,5,3,6-Tetrazadiphosphorinanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reactions of methylhydrazine with RPC12 (R = Et, tBu, and Ph) produced the cyclic phosphorus (III) hydrazides (1,2,4,5,3,6-tetrazadiphosphorinanes) [RPN(Me)N(H)2 (R = Et, 1; (Ph, 2; tBu, 3) in good yields. The 1H-and 31P-NMR spectroscopic analysis indicated that 1 exists in chair and boat conformations. However, it crystallizes in the chair conformation exclusively. The X-ray crystallographic investigation of all the three cyclo-phosphorus hydrazides 1-3 confirms the existence of these compounds in the chair conformations in the solid state. The reaction of Mo(CO)4-(NHC5H10)2 with 1 and 2 gives the dinuclear Mo(0) complexes [{Mo(CO)4(NHC5H10)}2(μ-[RPN(Me)N(H)]2}] (R = Et, 5; Ph, 6). Based on 1H- and 31P-NMR spectroscopic data, a bridging dinuclear dimetallic formulation is proposed for 5 and 6. The IR spectra indicate that the carbonyls are disposed in cis-geometry around the Mo(0) center.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270603
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  • 163
    Digitale Medien
    Digitale Medien
    Elektrophile Additionen an das Bicyclo[1.1.0]butan-System von 1-Phenyl- und 1-(4-Anisyl)tricyclo[4.1.0.02,7]heptan: Säure-katalysierte Reaktionen mit Wasser und Methanol, Anlagerung von Essigsäure und OxymercurierungHerrn Professor Helmut Quast zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 367-379 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 6-Norpinanols ; 6-aryl- ; preparation ; 6-Norpinyl 3,5-dinitrobenzoates ; hydrolysis ; Carbocations ; generation and rearrangement ; 2-Norcaranols ; 1-aryl- ; Cyclohept-3-en-1-ols, 3-aryl-, conformation ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electrophilic Additions to the Bicyclo[1.1.0]butane System of 1-Phenyl- and 1-(4-Anisyl)tricyclo[4.1.0.02,7]heptane: Acid-Catalyzed Reactions with Water and Methanol, Addition of Acetic Acid, and Oxymerucuration1-(4-Anisyl)tricyclo[4.1.0.02,7]heptane (37) was prepared from 1-(4-anisyl)cyclohexene, tetrabromomethane, and methyllithium in a one-pot reaction. Starting from 37 and the analogous phenyl compound 19, the oxymercuration/demercuration sequence provided the exo-6-aryl-endo-6-norpinanols 30a and 20a, respectively. By reaction with triphenyl-stannane, the bromo compound 27a was converted into endo-6-phenyl-exo-6-norpinanol 28a. Treatment of 19 with aqueous sulfuric acid led to a mixture of the alcohols 20a-25a. Mixtures of a very similar composition were obtained on hydrolysis of the 3,5-dinitrobenzoates 20b and 28b of 20a and 28a in 80% aqueous acetone. Kinetic measurements revealed the same rate for the hydrolysis of 20b and 28b. The proof of the presence of 20a among the products of the reactions of 19, 20b, and 28b showed the intermediacy of an unrearranged cation, to which the classical structure 16 is ascribed. That acetic acid is too weak a nucleophile to intercept 16 follows from the structure of the adducts to 19. All of them (21b, 22b, 25b, 26b) have rearranged skeletons. In contrast, the stronger nucleophile methanol trapped 16 more efficiently than water to give the diastereomeric 6-norpinyl methyl ethers 20d and 28d. The reaction of 37 with acetic acid and 10-4 M hydrochloric acid as well as the hydrolysis the 3,5-dinitrobenzoate 30c of 30a produced mainly the diastereomeric 6-norpinyl acetates 30b and 31b and 6-norpinanols 30a and 31a, respectively. Whereas the protonation of 19 and 37 gives the classical cations 16 and 17, respectively, the oxymercuration of these substrates results in the generation of the nonclassical cations 44 and 46. This was concluded from the configuration of the demercuration products 20a and 30a and the absence of the diastereomers 28a and 31a.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270214
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  • 164
    Digitale Medien
    Digitale Medien
    Chlorotrioxorhenium. Neue Synthesen, Reaktionen und Derivate (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 47-54 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Rhenium compounds ; Thermogravimetry ; Organometallic Oxides ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Multiple Bonds between Main Group Elements and Transition Metals, CXXIX[1].  -  Chlorotrioxorhenium. Novel Syntheses, Reactions, and DerivativesChlorotrioxorhenium (1a) and homologs of formula X-ReO3 (1b-e) are generated from Re2O7 and either ZnX2, (n - C4H9)3SnX, [(n-C4H9)4N]X, or [(C6H5)4P]X in clean reactions. Compounds 1a-f form with stable six-coordinate adducts XReO3 ·L (2a-f, 3a, 4a, 5a: L = N,N′-ligand) upon addition of the free ligand L, e.g. 2,2′-bipyridine. 1a is readily alkylated by means of SnR4 or ZnR2 to form organorhenium(VII) oxides in good yields. These synthetic routes have the advantage to proceed under very mild conditions. The adducts of 2,2′-bipyridine with halorhenium(VII) oxides show characteristic thermogravimetric (TG) behavior that reflects the volatility of the uncoordinated complexes X-ReO3.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270108
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  • 165
    Digitale Medien
    Digitale Medien
    Synthese und Charakterisierung von Gallium-Phosphor-Heterocubanen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 67-71 
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    ISSN: 0009-2940
    Schlagwort(e): Gallium compounds ; Heterocubanes, gallium-phosphorus ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and Characterization of Gallium-Phosphorus HeterocubanesThe reaction of iPrGaCl2 with tBuPLi2 in Et2O at -78°C gives the heterocubane [iPrGaP(tBu)]4 (1) by using the “dilution principle”. {(MesGa)3[GaP(H)tBu][P(tBu)]4} (2) was formed, when three equivalents of MesGaCl2 and one equivalent of GaCl3 in THF at -78°C were treated with 5 equivalents of tBuPLi2. Compounds 1 and 2 were characterized by NMR, IR, and MS techniques as well as by X-ray structure determination. The heterocubane molecules of 1 are disordered in the crystal; every atom site of the central cubical frame work is occupied by gallium and phosphorus atoms (occupation factor 0.5). The structure of 2 contains two crystallographically unique molecules, which are not disordered because of the additional P(H)tBu groups.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270110
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  • 166
    Digitale Medien
    Digitale Medien
    Zur Chemie der Galliumverbindungen, II. Darstellung und Struktur von Bis(2,2,6,6-tetramethylpiperidino)-[tris(trimethylsilyl)silyl]gallium  -  ein erstes Beispiel für ein monomeres Bis(amino)gallan mit Gallium-Silicium-Bindung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 101-103 
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    ISSN: 0009-2940
    Schlagwort(e): Gallium bis(amides) ; Gallium-silicon bond ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: On the Chemistry of Gallium Compounds, II[1].  -  Preparation and Structure of Bis(2,2,6,6-tetramethylpiperidino)-[tris(trimethylsilyl)silyl]gallium  -  ein First Example for a Monomeric Bis(amino)gallane with Gallium-Silicon BondThe title compound tmp2GaSi(SiMe3)3 (4) (tmp = 2,2,6,6-tetramethylpiperidino) was prepared by the reaction of (Me3Si)3SiLi · 3 THF (2) with tmp2GaCl (3). The NMR data (1H, 13C, 29Si) and the crystal structure of 4 are discussed. It contains a trigonal planar-coordinated gallium atom with long Ga-N and Ga—Si bonds of 191 and 247 pm, respectively. This compound is the first fully characterized monomeric gallium bis(amide) and the second structurally investigated compound with a gallium-silicon bond.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270117
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  • 167
    Digitale Medien
    Digitale Medien
    Synthesis of 5-Methoxy- and 5-(Dialkylamino)bicyclo[3.2.0]hept-2-en-6-one Derivatives by cine Substitution with Methoxide Anions and Dialkylamines (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 137-144 
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    ISSN: 0009-2940
    Schlagwort(e): Bicyclo[3.2.0]hept-2-en-6-one, cine substitution ; DSC ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: exo-7-Chloro-endo-7-phenylbicyclo[3.2.0]hept-2-en-6-one (5) undergoes cine substitution reactions with methoxide anions and with dialkylamines to give 5-methoxy or 5-dialkylamino derivatives 13, 14, 16-19 in high yield. While attempts directed to an acetalization have failed, the addition of Grignard reagents to the methoxy derivatives proceeds stereoselectively in high yield. Hydrochlorides 20/21 lose amine at 110°C to form 2-phenyltropone (22). Thermolysis of diethylamino derivative 24 at 170°C (temperature determined by DSC) results in the formation of the dienaminone 25.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270122
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  • 168
    Digitale Medien
    Digitale Medien
    Stereoselektive Protonierung von Carbanionen, 2. Diastereoselektive Protonierung von Schöllkopf-Bislactimether-Anionen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 165-172 
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    ISSN: 0009-2940
    Schlagwort(e): Diastereoselectivity ; Protonation ; Pyrazines ; dialkoxydihydro- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stereoselective Protonation of Carbanions, 2[1].  -  Diastereoselective Protonation of Schöllkopf's Bislactim Ether AnionsThe anions of the bis-lactim ethers 5-7 serve as models for a systematic investigation of diastereoselective protonation. From 5Li, 6Li, and 7Li in THF at -78°C 30 proton sources (—OH, —NH, —SH, —CH) of different acidity and bulkiness produce the following cis/trans ratios: 5 8:92 → 37:63; 6 15:85 → 48:52; 7 25:75 → 59:41 (equilibria ≈ 50:50). Substitution of R1 = iPr in 5 by Me (→ 6) decreases the stereoselectivity slightly, but substitution of OMe in 6 by OEt (7) much stronger (Table 1). Most of the added Lewis acids show week or even leveling effects, whereas with 5K a dramatic change is observed with cis/trans-5 = 27:73 → 89:11 (Table 2). By variation of solvent and several additives only minor effects on the cis/trans ratio are observed (Table 3). Backed by 13C—NMR spectra of the ion pairs and literature data protonation of 5Li-7Li is supposed to occur on a dimer, which will mainly react to give trans-5-7. The prevailing formation of cis-5 from 5K is explained by the reaction of the monomeric ion aggregat.
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270125
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  • 169
    Digitale Medien
    Digitale Medien
    Photolyse von Naphth[2,3-d]-1,2,3-oxadiazol  -  Ein Beitrag zum Oxiren-Problem (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 551-555 
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    ISSN: 0009-2940
    Schlagwort(e): Naphth[2,3-d]-1,2,3-oxadiazole ; 2,3-Naphthoquinone diazide ; Wolff rearrangement, photochemical ; Naphth[2,3-b]oxirene ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photolysis of Naphth[2,3-d]-1,2,3-oxadiazole  -  A Contribution to the Oxirene ProblemThe photolysis of [9a-13C]naphth[2,3-d]-1,2,3-oxadiazole ([9a-13C]14) in methanol, water, and cyclohexane is studied. In the protic solvents, the Wolff rearrangement products 2-(methoxycarbonyl)indene ([13C=O]16) and 2-indenecarboxylic acid ([13C=O]23) exclusively labelled at the carbonyl carbon are obtained. Furthermore, the photolysis of [9a-13C]14 in methanol yields [2-13C]-2-naphthol (19) as hydrogen abstraction product. The photolytic decomposition of 14 in cyclohexane affords 2-(2-naphthoxycarbonyl)indene (25) and 1-cyclohexyl-2-(2-naphthoxycarbonyl)indene (26). The formation of 25 is explained by nucleophilic addition of 2-naphthol (19) to the intermediate ketene 21. 2-Naphthol (19) is generated in situ by hydrogen abstraction from cyclohexane. The cyclohexyl radicals, thereby obtained, convert 25 to 26. Similar photolysis of [9a-13C]14 affords [13C—O—13C=O]25 and [13C—O—13C=O]26 labelled at the carbonyl carbon and C-2 of the naphthalene ring. Thus, independent of the nature of the solvent (methanol, water, cyclohexane), no labelling distribution is found in the photolysis products of [9a-13C]14. This excludes the participation of naphth-[2,3-b]oxirene (17) as reactive intermediate.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270315
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  • 170
    Digitale Medien
    Digitale Medien
    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A31 
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    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270320
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  • 171
    Digitale Medien
    Digitale Medien
    Synthesis and Crystal Structures of Copper(I) and Gold(I) Complexes [C(NH2)3]2[M2(1,2-dithiosquarate)2], M = Cu, Au, Containing Short M···M Distances, and of the Gold(III) Complex (cycloPrPh3P)[Au(1,2-dithiosquarate)2] (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 605-609 
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    ISSN: 0009-2940
    Schlagwort(e): Copper(I) complexes ; Gold(I) complexes ; Dithiosquarates ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The new compounds [C(NH2)3]2[Cu2(dtsq)2] (1), [C(NH2)3]2-[Au2(dtsq)2] · H2O (2), and (cycloPrPh3P)[Au(dtsq)2] (3, cycloPr = cyclopropyl) have been prepared from CuSO4 · 5 H2O, KAuCl4, and K2dtsq · H2O (dtsq = dianion of 1,2-dithiosquaric acid, C4O2S2-2). Compounds 1 and 2 contain pairs of metal atoms with short intermetallic distances of 2.587(2) (Cu···Cu) and 2.846(2) Å (Au···Au). Cu(I) is trigonally coordinated to three sulfur atoms of three different ligands and lies 0.51 Å above the S3 plane. It is oriented towards the copper atom of a second CuS3 unit related to the first one by a center of inversion. Au(I) shows a linear coordination, leading to the formation of Au2(dtsq)2-2 dimers. These have intermolecular Au···Au distances of 3.259(2) Å. Compound 3 contains isolated Au(dtsq)-2 ions with square planar coordination geometry stacked along the a axis at 4.708 Å distance.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270404
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  • 172
    Digitale Medien
    Digitale Medien
    Metal Complexes with Tetrapyrrole Ligands, LXVI. Synthesis, Characterization, and Variable-Temperature 1H- and 19F-NMR Investigations of Cerium(IV) Double-Deckers Derived from Monofunctionalized Tetraarylporphyrins (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 589-595 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cerium(IV) bisporphyrinates ; Monofunctionalized tetraarylporphyrins ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of a cerium(IV) bisporphyrinate 1b starting from (p-hydroxyphenyl)tris(p-tolyl)porphyrin 2b is described. Derived from 2b by substitution of the phenolic OH group, the monofunctionalized tetraarylporphyrins 2c-f and their cerium(IV) sandwich complexes 1c-f were synthesized. The complexes are characterized by UV/Vis, IR, and 1H-NMR spectroscopy. 19F-NMR spectra of 1f show the presence of a vicinal and a transversal isomer due to the rigid squareantiprismatic coordination geometry of cerium(IV) bisporphyrinates. Variable-temperature 1H- and 19F-NMR spectra were recorded to investigate the rotational rigidity of the double-decker system. The spectra show that the vicinal and transversal isomers are stable up to 140°C, i.e. rotation of the two porphyrin macrocycles with respect to each other does not occur.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270402
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  • 173
    Digitale Medien
    Digitale Medien
    Synthese und Struktur von (R3P)Ni(1,6-Heptadiin)-Komplexen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 653-655 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1,6-Diynes ; Nickel complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and Structure of (R3P)Ni(1,6-Heptadiin) ComplexesDisplacement of the alkene ligand in Ligand-Ni(0)(1,6-diene) complexes by 1,6-heptadiyne, the parent 1,6-diyne, affords the complexes (Me3P)Ni(η2,η2-C7H8) (1) and (Ph3P)Ni(η2,η2-C7H8) (2). According to an X-ray structure analysis of the PMe3 derivative 1 the nickel atom is ideally trigonal-planar coordinated by the phosphane and both C≡C bonds. The increased stability of the complexes as compared to Ligand-Ni(HC≡CH)2 complexes is referred to the strong chelating effect which is special to the 1,6-functionalization. The compounds can be considered to be model complexes for the key intermediates of numerous transition metal-mediated coupling reactions of (substituted and unsubstituted) 1,6-diynes.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270413
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  • 174
    Digitale Medien
    Digitale Medien
    Reaction of (α,β-Epoxyalkyl)silanes with α-Sulfonyl Anions and α-Sulfonyl Anions in the Presence of a Lewis Acid. A Method for the Synthesis of (Z)-sec-Allylic Alcohols and β,γ-Unsaturated Alkyl Phenyl Sulfones (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 677-683 
    Details
    ISSN: 0009-2940
    Schlagwort(e): (α,β-Epoxyalkyl)trimethylsilane reactions ; α-Sulfonyl anions ; Allylic alcohols ; β,γ-Unsaturated alkyl phenyl sulfones ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of 2-alkyl-3-(trimethylsilyl)oxiranes (la or 1b) with anions generated from alkyl phenyl sulfones (2a-f) followed by hydrolysis affords sec-allyl alcohols 3-7. An analogous reaction in the presence of BF3 · Et2O affords adducts 8-11. Treatment of 8-11 with NaOH under phase-transfer conditions affords stereospecifically the corresponding allylic alcohols 4a-5c. Reaction of oxirane 1a with anions derived from sterically hindered sulfones 2e or 2f in the presence of BF3 · Et2O was investigated. Reaction of compounds 8, 9 with phosphorus tribromide in pyridine affords β,γ-unsaturated sulfones 19.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270417
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  • 175
    Digitale Medien
    Digitale Medien
    Synthese, Kristallstruktur und Reaktionen neuartiger metallacyclischer Dioxo- und Aminooxocarben-Komplexe des Eisens (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 711-715 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Iron compounds ; Carbene complexes ; Metallacycles ; 2H-Pyrans ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis, Crystal Structure, and Reactions of Novel Metallacyclic Dioxo- and Aminooxocarbene Complexes of IronThe novel cationic iron carbene complexes 9 and 11 are readily prepared from the corresponding ferra lactones 7 and lactams 10, respectively. With nucleophiles the complexes 9 react chemoselectively either at the methyl group of the methoxy residue or at the terminal allylic C atom. In contrast to similar tungsten complexes 6, compounds 9 show “carbene activity” only when olefin and carbene ligands are separated by two atoms. Novel tricarboryl(2H-pyran)iron complexes 18 are obtained by a regioselective intramolecular carbene transfer in 9 once switched to the active form 17 by deprotonation using silyl enol ether 16 as a base.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270421
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  • 176
    Digitale Medien
    Digitale Medien
    Organische Synthesen mit Übergangsmetallkomplexen, 71. Methylcarben-Komplexe von Chrom und Wolfram mit Cycloheptatrienyl-, Cyclohexadienyl[Fe(CO)3]- und Cycloheptadienyl[Fe(CO)3]-Resten als α-Substituenten (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 731-738 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Methylcarbene complexes of chromium and tungsten ; Cyclohexadienyl tricarbonyliron, carbene derivatives of ; Cycloheptadienyl tricarbonyliron, carbene derivatives of ; Cycloheptatrienyl, carbene derivatives of ; Enol ether, elimination from carbene complexes ; Spirocyclopropanes, elimination from carbene complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organic Syntheses via Transition Metal Complexes, 71[1].  -  Methylcarbene Complexes of Chromium and Tungsten with Cycloheptatrienyl-, Cyclohexadienyl[Fe(CO)3]- and Cycloheptadienyl[Fe(CO)3] SubstituentsMethylcarbene complexes LnM=C(OEt)CH3 1 [LnM = (CO)5Cr, (CO)5W] react with tropylium tetrafluoroborate (2a) or coordinated olefins of [C6H7Fe(CO)3]BF4 (2c), [C7H9Fe-(CO)3]BF4 (2d), and [C7H7Fe2(CO)6]BF4 (2d) in the presence of Et3N to give complexes LnM=C(OEt)CH2R 3a-e and LnM=C(OEt)CHR2 7a-d by substitution of one or two α-hydrogen atoms. The trimetallic WFe2 carbene complexes 7c, d derived from 1b with 2c, d form three stereoisomers each, which are fully characterized spectroscopically, (R*,R*,S*)-7c additionally also by an X-ray structure analysis, Ligand elimination from 3 and 7 may involve a-and/or β-hydrogen transfer reactions: Thus enol ethers (Z/E)-6 are eliminated from α-monosubstituted methylcarbene complexes 3a, c, d in yields of 62-90% by a pyridine-induced transfer of an α-hydrogen to the carbene carbon atom; with increasing steric demand of R the elimination of the (Z) isomer (Z)-6 from 3 is favoured over the formation of the (E) isomer (E)-6. The enol ether 10 becomes a minor side product in the pyridine-induced ligand elimination from α-disubstituted complexes 7a, b. In these cases the spirocyclopropane 8 is formed as the main product (60-82%) besides the 4,5-homotropylidene 9 by a conformationally directed β-hydrogen transfer reaction.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270424
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  • 177
    Digitale Medien
    Digitale Medien
    Gürtelförmige Moleküle mittels repetitiver Synthesestrategie (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 767-777 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Azaphanes ; Cyclophanes ; Macrocycles ; Molecular belts ; Multistep strategy ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Belt-Shaped Molecules by a Repetitive Synthetic StrategyBelt-shaped molecules of the general type 2 containing up to five benzene ring units (cf. 37) have been synthesized by macrocyclisation reactions of ribbon-shaped precursors. An intermolecular cyclization step generates the macroheterocycles 38 and 40. The fourfold-bridged cyclophane 36 are prepared by intra-and intermolecular cyclization reactions. The X-ray structure analyses of 14, 16, 22, 23, 28, and 36 show S-shaped conformations of the molecules.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270428
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  • 178
    Digitale Medien
    Digitale Medien
    Kleine Ringe, 83. C3F2-Isomere: Erzeugung durch gepulste Blitzpyrolyse und matrixspektroskopische Identifizierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 779-782 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Matrix isolation ; Photochemistry ; Flash pyrolysis ; Carbenes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Small Rings, 83[1].  -  C3F2 Isomers: Generation by Pulsed Flash Pyrolysis and Matrix-Spectroscopic IdentificationMatrix-isolated difluorovinylidenecarbene (4) has been generated by pulsed flash pyrolysis from 1-chloro-3,3-difluoro-cyclopropene (8a) and 3,3-difluoro-1,2-diiodocyclopropene (8b). By subsequent photolysis 4 isomerizes to difluoropropargylene (5) and difluorocyclopropenylidene (6). The identification of the three new carbenes is based on the comparison of their experimental and calculated (MP2/6-31G*) infrared spectra.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270429
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  • 179
    Digitale Medien
    Digitale Medien
    Distinction of Fe+—NCH and Fe+—CNH Complexes by Gas-Phase Ion-Molecule Reactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 791-793 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Transition-metal ion chemistry ; O2-bond activation ; Bond dissociation energies ; Rate constants ; Ion cyclotron resonance mass spectrometry ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The bond dissociation energies and the heats of formation of the complexes Fe+—NCH (6) and Fe+—CNH (10) have been determined. The HCN ligand in 6 is by 3 kcal/mol less strongly bound to Fe+ than HNC in 10, and complex 6 is 13 kcal/mol more stable than 10. Isomerization of 10 to 6 is difficult if not impossible to bring about as, upon collisional activation, mutual isomerization cannot compete with ligand detachment. In addition, the ion-molecule reactions of 6 and 10 with O2 give rise to distinct product distributions.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270432
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  • 180
    Digitale Medien
    Digitale Medien
    Synthesis and Characterization of Soluble Oligo(9,10-anthrylene)s (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 437-444 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Reductive coupling ; Oligo(9,10-anthrylene)s, derivatization of, cyclization of ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A homologous series of oligo(9,10-anthrylene)s up to the heptamer have been synthesized by reductive coupling of quinones with lithioanthrylenes, followed by reductive aromatization of the intermediate hydroxy species. The method used allows the introduction of different alkyl substituents, which ensure sufficient solubility of the newly synthesized anthrylene systems in common organic solvents. The solid-state conformations of trimers 4 and 5 have been established by X-ray structure analysis; UV/Vis-spectroscopic investigations in solution reveal the anthracene moieties in 9,10-anthrylenes to exist as electronically independent electrophores. The trianthrylenes can be subjected to electrophilic substitution which regioselectively provides e.g. 10-bromo- and 10,10″-dibromo derivatives. These bromides can easily be converted into the corresponding cyano compounds. Under the influence of potassium hydroxide in quinoline the trimer 5 partially cyclizes to helianthrene compounds.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270221
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  • 181
    Digitale Medien
    Digitale Medien
    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A19 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270223
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  • 182
    Digitale Medien
    Digitale Medien
    Radikalische Cyclisierung von Dienen, VIII. Über die regioselektive Herstellung von ungesättigten Cyclopenta[b]furan-2-onen aus (S)-(+)-Carvon  -  Bausteine zur Synthese von enantiomerenreinen Triquinanen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 549-550 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Radicals ; Cyclization ; Triquinanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Radical-Type Cyclization of Dienes, VIII[1].  -  On the Regioselective Synthesis of Unsaturated Cyclopenta[b]furan-2-ones from (S)-(+)-Carvone  -  Building Blocks for the Synthesis of Enantiomerically Pure TriquinanesThe diastereomeric products 2a and 2b, which were synthesized from (S)-(+)-carvone (1), are converted to (3aS,5S,6aS)-(-)-5-acetoxyhexahydro-6a-methyl-2H-cyclopenta[b]furan-2-one (4) in ca. 50% yield. 4 is regioselectively converted to (3aR,6aS)-(-)-3,3a,6,6a-tetrahydro-6a-methyl- (8a) and (3aS,6aR)-(+)-3,3a,4,6a-tetrahydro-6a-methyl-2H-cyclopenta[b]-furan-2-one (8b). These are used at the 10-g scale for the synthesis of enantiomerically pure triquinanes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270314
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  • 183
    Digitale Medien
    Digitale Medien
    Ein neuartiger Einstieg in Wittig-Umlagerungen  -  Eine stereoselektive [1,2]-Wittig-Umlagerung mit Konfigurationsumkehr am Carbanion-Zentrum (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 585-585 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270319
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  • 184
    Digitale Medien
    Digitale Medien
    J-Aggregate von 4-Iod-bis(dimethylamino)heptamethinium-triiodid Synthese, Struktur und optische EigenschaftenHerrn Professor Reinhard Schmutzler zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 893-896 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Iodination ; Streptopolymethine ; Cyanine dye aggregates ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: J-Aggregates of 4-Iodo-bis(dimethylamino)heptamethine Triiodide.  -  Synthesis, Structure, and Optical PropertiesIodination of heptamethincyanine 2a gives the title compound 3. Its cations display all-trans configuration in solution and in the crystalline state. In contrast to cations of 2a, those of 3 form one-dimensional J aggregates, as proved by X-ray analysis and optical reflection spectroscopy.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270517
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  • 185
    Digitale Medien
    Digitale Medien
    Erzeugung von 2-substituierten 1-Ethenyl-Kationen aus Ethylendiazonium-Salzen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 933-939 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Ethylenediazonium salts, thermal stability of, thermal degradation of ; Ethenyl cations, generation of, rearrangement of, interception of ; Kinetics ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thermal decomposition of 2-substituted ethylenediazonium salts 1a-d produces the corresponding 1-ethenyl cations 2a-d as short-lived intermediates. The primary vinyl cation 2d or the rearranged and energetically favored analogues 3a-c of 2a-c are intercepted by chloride to give the decomposition products 4d and 5a-c, respectively. The generation of 4d and 5a-c as well as a kinetic study of the thermolysis reaction provide no indication that the elimination of nitrogen from 1a-d is occurring with the intermediate formation of cyclic cations 6 or 7.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270522
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  • 186
    Digitale Medien
    Digitale Medien
    Cycloadditionen von 2H-Benzo[b]thiet und Verbindungen mit kumulierten Doppelbindungen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 955-958 
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    ISSN: 0009-2940
    Schlagwort(e): Hetero Diels-Alder reactions ; Chemoselectivity ; Regioselectivity ; Stereoselectivity ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cycloaddition Reactions of 2H-Benzo[b]thiete and Compounds with Cumulated Double Bondso-Thiobenzoquinone methide (2), generated by thermal ring opening of 2H-benzo[b]thiete (1), reacts with allene 3, ketene imine 7, the carbodiimides 9a-c, and the N-sulfinylamines 11a-c in highly specific [8π + 2π] cycloaddition processes to form novel types of heterocyclic systems 4, 8, 10a-c, and 12a-c with exocyclic double bonds. The 1:1 adduct 4 can add a further molecule of allene to yield the spiro compounds 5 and 6.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270525
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  • 187
    Digitale Medien
    Digitale Medien
    Bimolecular Formation of Radicals by H-Transfer, 6. Uncatalyzed Transfer Hydrogenation of a Benzhydryl Fluoride by 9,10-Dihydroanthracene (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 557-563 
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    ISSN: 0009-2940
    Schlagwort(e): Hydrogen transfer ; Molecule-induced radical formation ; Reduction of C—F bond ; 1-Adamantylfluorodiphenylmethane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1-Adamantylfluorodiphenylmethane (2) was reduced to 1-adamantyldiphenylmethane (3) when heated with 9,10-dihydroanthracene to 330°C. From the second-order kinetics, the activation parameters (ΔH
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270316
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  • 188
    Digitale Medien
    Digitale Medien
    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270401
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  • 189
    Digitale Medien
    Digitale Medien
    Synthese, Deprotonierung und Ringerweiterung eines 2,3-DiboratetralinsHerrn Prof. Dr. Helmut Werner zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 611-613 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 2,3-Diboratetralin,2,3-bis(dimethylamino)- ; 2,3-Diboranaphthalenediide,2,3-bis(dimethylamino)- ; 2,5-Benzodiborocine,2,5-bis(dimethylamino)-3,4-diethyl-1,2,5,6-tetrahydro- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis, Deprotonation, and Ring Expansion of a 2,3-DiboratetralinHerrn Prof. Dr. Helmut Werner zum 60. Geburtstag gewidmet.Reaction of K2[1,2-C6H4(CH2)2] with [Cl(Me2N)B]2 leads to 2,3-bis(dimethylamino)-2,3-diboratetralin (4a) in 58% yield. Deprotonation of 4a with lithium 2,2,6,6-tetramethylpiperi-dide yields the crystalline dilithium salt 6a. Insertion of 3-hexyne into the B—B bond of 4a results in the formation of 2,5-bis(dimethylamino)-3,4-diethyl-1,2,5,6-tetrahydro-2,5-benzodiborocine (7a) in 38% yield. The constitutions of 4a, 6a, and 7a were derived from 1H-, 11B-, 13C-NMR, and MS data and proven for 6a and 7a by X-ray,structure analyses.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270405
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  • 190
    Digitale Medien
    Digitale Medien
    Metallkomplexe funktioneller Isocyanide, XXIII. N-Isocyandialkylamin-Komplexe des Bors, Rhodiums, Palladiums, Platins und Kupfers (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 631-637 
    Details
    ISSN: 0009-2940
    Schlagwort(e): N-Isocyanodialkylamines ; N-Isocyanide metal complexes ; Homoleptic complexes ; Stabilization by coordination ; N—N Bond cleavage ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Metal Complexes of Functional Isocyanides, XXIII[1]. - N-Isocyanodialkylamine Complexes of Boron, Rhodium, Palladium, Platinum, and CopperThe N-isocyanodialkylamines CNNEt2, CNNiPr2, and CNNCH(Me)(CH2)3CHMe (1a-c) react with triphenylboron, various transition metal halides, and mono- and dinuclear chloro complexes by addition, substitution, bridge cleavage and reduction to give the complexes Ph3BCNNR2 (2b, c), [MX2(CNNR2)2] (M = Pd, Pt; X = Cl, Br, I) (3-7), [M(Cl)-(CNNR2)(PPh3)2]BF4 (8, 9), cis- and trans-[PtCl2(CNNR2)-(PR′3)] (R′ = Et, Ph) (10-12), [Rh(CNNR2)4]Cll (15b, c) and [Cu(CNNR2)4]ClO4 (16b, c). The complexes [PdX2(CN—NR2)(PPh3)] (X = Cl, Br) (13c, 14c) have been obtained by substitution of an N-isocyanide ligand in 3c and 4c, respectively, with PPh3. The structural assignments are made on the basis of IR, NMR (1H, 13C, 31P, 15N) and mass spectrometry as well as of an X-ray structure analysis of [PdI2(CNNiPr2)2] (5b).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270408
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  • 191
    Digitale Medien
    Digitale Medien
    Reaktive E=C(p-p)π-Systeme, XXXVII. Pentafluorethanselenol: Synthese, Spektren und Gasphasen-StrukturHerrn Professor Wolfgang Sawodny zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 647-650 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Ethaneselenol, pentafluoro-, IR, Raman, NMR, electron diffraction ; ab initio Calculation ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactive E=C(p-p)π Systems, XXXVII[1]. - Pentafluoroethaneselenol: Synthesis, Spectra, and Gas-Phase StructureHerrn Professor Wolfgang Sawodny zum 60. Geburtstag gewidmet.Pentafluoroethaneselenol HSeC2F5 (1) and its deuterated analogue DSeC2F5 (2) are obtained in moderate yields by cleavage of the diselane (SeC2F5)2 with Me3SnH and Me3SnD, respectively. Complete characterization of the labile compounds was accomplished by spectroscopic investigations (IR, Raman, MS; 1H, 13C, 19F, 77Se NMR). The molecular structure was determined by electron diffraction in the gas phase together with ab initio calculations.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270411
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  • 192
    Digitale Medien
    Digitale Medien
    Alkyleisen- und Alkylcobalt-Reagenzien, IX. Umlagerung aliphatischer terminaler Epoxide zu Methylketonen durch Eisenalkyl-Reagenzien statt durch Co2(CO)8 oder Edelmetallkatalysatoren (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 659-665 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Organoiron compounds ; Iron catalysts ; Ketone synthesis ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alkyliron and Alkylcobalt Reagents, IX[1].  -  Rearrangement of Aliphatic Terminal Epoxides to Methyl Ketones by Iron Alkyl Reagents instead of Co2(CO)8 or Noble Metal CatalystsThe highly selective rearrangement of aliphatic terminal epoxides to methyl ketones, hitherto possible only with Co2(CO)8 or noble metal catalysts, occurs smoothly with Me4-FeLi2, Me3FeLi, or the catalytic systems [RLi + 2.5 mol% FeCl3] (R = Me, Bu). This was demonstrated by the rearrangement of 1-decene oxide (1) to 2-decanone (2) (yield 80-81%; Table 1) and 6-bromo-1-hexene oxide (5) to 6-bromo-2-hexanone (6) (yield 78%, Me4FeLi2 applied only). The competition reaction of Me4FeLi2 with 1 and 2-octanone (8) (mole ratio 0.5:1:1) led to 87% 2-methyl-2-octanol (9) and not to the rearrangement 1 → 2. This indicates that Me4FeLi2 - in contrast to the opposite behavior of organo cuprates - reacts faster with ketones than with the aliphatic terminal epoxides. By treatment of 1 with methyl derivatives of MnII, CoII, and NiII or with Bu4FeLi2 (Table 2) other products (3, 4) besides 2 were formed. The rearrangement of 1 with Me4FeLi2 is assumed to start with an oxidative addition and yields 2 as its Li or Fe enolate (trapped with acetanhydride to give 64% of 20) after reductive elimination of CH4. The catalytic rearrangement of 1 with [MeLi + 0.25 mol% FeCl3] very probably occurs in an analogous manner with an super-ate complex Me4FeLi2(MeLi)n as the active species and the Li enolate of 2 as end product (Scheme 4). The aromatic terminal epoxides styrene oxide and α-methylstyrene oxide give various products in the reaction with Me4FeLi2 or Me3FeLi, including the deoxygenation products styrene and α-methylstyrene. These products are exclusively formed on treatment of the epoxides with Me4MnLi2. (Prepared, hitherto in the literature not described compounds: 7 and 10-15.)
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270414
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  • 193
    Digitale Medien
    Digitale Medien
    Bimolekulare Radikalbildung durch H-Transfer, 7. Katalyse der Transferhydrierung von α-Methylstyrol durch 9,10-Dihydroanthracen mit 7H-Benz[de]anthracen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 691-696 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Molecule-induced radical formation, kinetics of ; Catalysis ; ESR spectroscopy ; Radical clock ; Isokinetic relationship ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bimolecular Formation of Radicals by H-Transfer, 7[1].  -  Bimolecular Formation of Radicals via H-Transfer with Catalysis by 7H-Benz[de]anthraceneThe transfer hydrogenation of α-methylstyrene (2) by 9,10-dihydroanthracene (1) (DHA) with 7H-benz[de]anthracene (8) as a catalyst proceeds already at 210-260°C. Isotopic labeling, ESR spectroscopy, radical clock experiments, solvents effects, and thermochemical calculations support the postulated stepwise radical mechanism induced by bimolecular formation of radicals.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270419
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  • 194
    Digitale Medien
    Digitale Medien
    1,3,5-Triphenyl-2,4,6-trimesityl-1,3,5,2,4,6-triphosphatriborinane: A 6π-Electron Heteroaromatic LigandDedicated to Professor Dr. Dr. h. c. mult. E. 0. Fischer on the occasion of his 75th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 825-827 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chromium tricarbonyl(η6-1,3,5-triphenyl-2,4,6-trimesityl-1,3,5,2,4,6-triphosphatrnane)- ; 1,3,5,2,4,6-Triphosphatriborinane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation of tricarbonyl(η6-1,3,5-triphenyl-2,4,6-trimesityl-1,3,5,2,4,6-triphosphatriane)chromium (4) is reported. Its X-ray structure reveals an orientation of the Cr(CO)3 moiety with respect to the almost planar B3P3 ring typical of an arene metal tricarbonyl complex.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270506
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  • 195
    Digitale Medien
    Digitale Medien
    Dilithium-N,N′-bis(trimethylsilyl)hydrazid und ein Hydrolyseprodukt side-on und end-on an N2-2- und O2-2-gebundene Li-Kationen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 845-847 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Lithium compounds ; Hydrazines ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dilithium N,N′-Bis(trimethylsilyl)hydrazide and a Hydrolysis Product: Side-On- and End-On-Coordinated Li Cations to N2-2 and O2-2N,N′-Bis(trimethylsilyl)hydrazine is converted into the dilithium derivative [(Me3Si)2N2Li2] · 2 thf (1) by nBuLi. Compound 1 forms a tetramer which lies on a crystallographic inversion centre. The Li+ ions are found to be end-on to the N—N units and also coordinated by thf, but three Li+ ions are also positioned symmetrically above the N—N bonds. The hydrolysis of 1 in air leads to the formation of [(Me3SiOLi)4 · Li2O2 · LiN(SiMe3)2] · 2 thf (2) which contains four oxide and one peroxide ions. The O2-2 unit is side-on-coordinated by three Li+.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270510
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  • 196
    Digitale Medien
    Digitale Medien
    Chirale Lactole, XI. Eine Methode zur Bestimmung der Absolutkonfiguration chiraler Alkanole (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 887-892 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Configuration, absolute ; Alkanols, chiral ; Acetals ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Chiral Lactols, XI. - A Method for the Determination of the Absolute Configuration of Chiral AlkanolsChiral secondary alcohols which are protected with the enantiomerically pure lactol 1 or 2 show significant differences in 13C-chemical shifts around the glycosidic linkage. An easy method for determination of the absolute configuration of secondary alcohols based on this fact is described.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270516
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  • 197
    Digitale Medien
    Digitale Medien
    Dendrimere und Dendrimer-Bausteine mit trisubstituiertem Benzol und “Hexacyclen” als Kern (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 897-903 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Dendrimers ; Supramolecular chemistry ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dendrimers and Dendrimer Building Blocks with Trisubstituted Benzene and “Hexacyclene” as Core UnitsThe preparation of new dendritic compounds containing 1,3,5-substituted aromatic units or “hexacyclene” is described. Bulky dendrimers are obtained in few generations starting with polyfunctional core units like 1, 4, 5, 12, and hexacyclene (21). The dendrimers were synthesized by using both the divergent method (for 7) and the convergent method (for 13 and 22). 22 is the first dendrimer containing a crown unit as core.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270518
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  • 198
    Digitale Medien
    Digitale Medien
    Flüchtige Metallalkoxide nach dem Konzept der donorfunktionalisierten Liganden (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 821-824 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Alkoxide complexes ; Manganese complexes ; Iron complexes ; Cobalt complexes ; Zinc complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Volatile Metal Alkoxides According to the Concept of Donor-Functionalized LigandsHomoleptic metal(II) alkoxides 3-5 of manganese, iron, cobalt, and zinc are prepared by applying the concept of donor-functionalized ligands. The trifunctional ether ligands 1 thus form volatile metal alkoxides that sublime below 100°C at 10-2 mbar. Monomeric molecules are present in the gas phase and are likely to occur in the solid state, too. The heterodimetallic alkoxide 6 (Li/Co) sublimes without decomposition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270505
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  • 199
    Digitale Medien
    Digitale Medien
    Synthesis of Silver(I) Complexes with the Bis(diphenylphosphanyl)-o-carborane Ligand. Crystal Structure of [Ag(phen){(PPh2)2C2B10H10}]ClO4 and [Ag{(SPPh2)2CH2}{(PPh2)2C2B10H10}]ClO4 · CH2Cl2 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 835-840 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Silver(I) complexes ; Bis(diphenylphosphanyl)-o-carborane ; o-Carborane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Silver(I) perchlorate or nitrate react readily with bis(di-phenylphosphanyl)-o-carborane to give the complexes [AgX{(PPh2)2C2B10H10}] [X = ClO4 (1), NO3, (2)]. The perchlorate ligand is weakly bound to the silver atom and thus can be displaced by other ligands affording the three-coordinated complexes [AgL{(PPh2)2C2B10H10}]ClO4 [L = PPh3 (3), PPh2Me (4), AsPh3 (5), C5H4NCOOH (6), C9H6NCOOH (7), SPPh3 (8)]. Compounds 3 and 4 can also be obtained by reaction of [Ag(OClO3)PR3] with the diphosphane. Treatment of complex 1 with bidentate ligands leads to the cationic four-coordinated [Ag(L—L){(PPh2)2C2B10H10}]ClO4 [L—L = (PPh2)2C2B10H10 (9), bipy (10), phen (11), (SPPh2)2CH2 (12)] or to the neutral [Ag(S2CNR2){(PPh2)2C2B10H10}] [NR2 = NEt2 (13), NC4H8 (14)]. The crystal structures of 11 and 12 have been established by X-ray crystallography. In both complexes the silver(I) atoms exhibit tetrahedral coordination by two phosphorus and two nitrogen or two sulfur atoms, respectively.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270508
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  • 200
    Digitale Medien
    Digitale Medien
    Zur Thermolyse von Amin - arachno-Nonaboran (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 853-855 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Diethylamine - arachno-nonaborane ; Diethylamine - octadecaborane ; conjuncto-Bis[6′5′:5,6]decaborane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: On the Thermolysis of Amine-arachno-NonaboraneTwo molecules of diethylamine-arachno-nonaborane, B9H13-(NHEt2), undergo a condensation at 140°C to give diethylamine-conjuncto-bis[6′,5′:5,6]decaborane, B18H20(NHEt2) (4). The deprotonation of 4 yields the anion [B18H19(NHEt2)]-which can be crystallized with the cation [NEt3(CH2Ph)]+ (space group P1).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19941270512
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