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  • 1
    Electronic Resource
    Electronic Resource
    Synthese und Struktur von Lithiumkomplexen mit pentahapto-gebundenen Tris(trimethylsilyl)cyclopentadienyl-Liganden (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1959-1967 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Lithium Complexes with pentahapto-Bonded Tris(trimethylsilyl)cyclo-pentadienyl LigandsReaction of tris(trimethylsilyl)cyclopentadienyllithium (2) with the nitrogen bases quinuclidine, tetramethylethylenediamine, and pentamethyldiethylenetriamine leads to the isolation of the crystalline, air-sensitive 1:1-adducts 3, 4, and 5, resp., which are monomeric in the gas phase, in solution, and in the solid state. X-Ray structure determinations show that in 3-5 the cyclopentadienyl ring is pentahapto-bonded to the lithium atom. The bonding in these π-complexes is discussed; the complex 3 fulfills the criteria for a nido-cluster.
    Notes: Umsetzung von Tris(trimethylsilyl)cyclopentadienyllithium (2) mit den Stickstoffbasen Chinuclidin, Tetramethylethylendiamin und Pentamethyldiethylentriamin führt zur Isolierung der kristallinen, luftempfindlichen 1:1-Addukte 3, 4 und 5, die in der Gasphase, in Lösung und im festen Zustand monomer vorliegen. Kristallstrukturuntersuchungen zeigen, daß in 3-5 der Cyclopentadienylring pentahapto an das Lithiumatom gebunden ist. Die Bindungsverhältnisse in diesen π-Komplexen werden diskutiert; der Komplex 3 erfüllt die Kriterien für einen nido-Cluster.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180520
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  • 2
    Electronic Resource
    Electronic Resource
    Synthese und Molekülstruktur zweier 1-Sila-3-alanata-cyclobutan-Derivate mit AlC2Si-Heterozyklus (1994)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1619-1626 
    Details
    ISSN: 0044-2313
    Keywords: C—H acidic aluminium organyls ; deprotonation of bis(trimethylsilyl)methyl groups ; AlC2Si heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Molecular Structure of Two 1-Sila-3-alanata-cyclobutane Derivatives with Four-membered AlC2Si-HeterocyclesThe C—H acidic bis(trimethylsilyl)methyl compounds Me3C—AlR2 und Me3C—CH2—AlR2 (R — CH(SiMe3)2) are deprotonated by treatment with the sterically high shielded base LiCH(SiMe3)2 in the presence of 1,3,5-trimethylhexahydrotriazinane. The deprotonation occurs at a methyl group of one of the element-organic substituents, and the formed carbanions are stabilized by coordination to the unsaturated Al atoms yielding four-membered heterocycles. Both products were characterized by a crystal structure determination each showing bent ring systems.
    Notes: Die C—H-aciden Bis(trimethylsilyl)methyl-Verbindungen Me3C—AlR2 und Me3C—CH2—AlR2 (R — CH(SiMe3)2) reagieren mit der sterisch sehr hoch abgeschirmten Base LiCH(SiMe3)2 in Gegenwart von 1,3,5-Trimethylhexahydrotriazinan unter Deprotonierung einer Methylgruppe des elementorganischen Substituenten; die dabei gebildeten Carbanionen stabilisieren sich durch eine Wechselwirkung zu dem koordinativ ungesättigten Al-Atom unter Ausbildung von viergliedrigen AlC2Si-Heterozyklen. Beide Produkte wurden durch eine Kristallstrukturbestimmung charakterisiert, die jeweils ein nicht-planares Ringsystem ergab.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19946200921
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  • 3
    Electronic Resource
    Electronic Resource
    Utilization of Industrial Waste Materials, 10Part 9, 8: Ref.[1]. - Part 7: Ref.[8].. - Synthesis of New Chiral Bicyclic 3-hydroxypiperidines - Highly Diastereoselective Ring Expansion of the Azabicyclo[3.3.0]octane System to Chiral Piperidine Derivatives (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 573-579 
    Details
    ISSN: 0947-3440
    Keywords: Amino alcohols ; Bicyclic pyrrolidine and piperidine derivatives ; Diastereoselective ring expansion ; Chiral auxiliaries ; Waste prevention ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New, chiral bicyclic 3-hydroxypiperidines (4S)-2a-e are synthesized from the β-amino alcohols (3R)-1a-e. In an one-step reaction (4S)-2a-e are obtained by a high diastereoselective ring expansion (dr ≥ 95:5). As well, the amino alcohol (3S)-1a leads to the corresponding rearranged epimer bicyclic piperidine derivative (4R)-2a (dr ≥ 95:5). Thus, it is possible to clarify the influence of the three stereogenic centers of the parent compound regarding the diastereoselectivity of the ring expansion. After oxidation of the tert-amino sec-alcohol (4S)-2a to the corresponding α-amino ketone 4, new 3-hydroxypiperidines (4Ξ)-5a, b12 and (4RS)-6 are obtained by a diastereoselective Grignard addition. Furthermore, the achiral and the chiral reduction of 4 to the β-amino alcohols (4S)-2a and (4R)-2a is described. These are further examples of the utilization of industrial waste material (all-R)-2-azabicyclo[3.3.0]octane-3-carboxylic acid (all-R)-3.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970319
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  • 4
    Electronic Resource
    Electronic Resource
    Utilization of Industrial Waste Materials, 11.Part 10: Ref. Synthesis of New, Chiral β-sec-Amino Alcohols - Diastereodivergent Addition of Grignard Reagents to α-Amino Aldehydes Based on the (all-R)-2-Azabicyclo[3.3.0]octane SystemDedicated to Professor Dieter Seebach on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2133-2146 
    Details
    ISSN: 0947-3440
    Keywords: Amino alcohols ; Chiral auxiliaries ; Diastereoselective Grignard reactions ; Proline analogues ; Homogenous catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New, chiral β-sec-amino alcohols (αR,βR)-11a-13a, (αS,βR)-11b-17b, (αS,βS)-11c, 12c, 15c, 17c and (αR,βS)-11d, 12d, 15d, 17d have been synthesized from the enantiomerically pure amine (all-R)-1a via diastereomeric, N-tert-butoxycarbonyl-protected aldehydes 3. Grignard additions proceed in fair yields with a high degree of diastereofacial stereoselection (diastereomeric ratios dr up to ≥ 95:5) with non-chelation control, generally in favor of the anti-(erythro) structures. A mechanistic interpretation of the stereochemical course of this reaction is presented. The stereodifferentiating ability of selected stereoisomeric (erythro)- and (threo)-amino alcohol structures were tested in homogeneous catalysis, e.g. in two model reactions (optical purities up to 95%).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971016
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  • 5
    Electronic Resource
    Electronic Resource
    Bis[tris(trimethylsilyl)methyl]diselenid: Ein ungewöhnliches Dichalkogenid mit sterisch erzwungener trans-C2h-Konformation (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2325-2327 
    Details
    ISSN: 0009-2940
    Keywords: Diselenide, torsion angle/NMR, 77Se/Selenenyl halide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis[tris(trimethylsilyl)methyl] Diselenide: An Unusual Diselenide with Sterically Enforced trans-C2h ConformationDeselenation of bis[tris(trimethylsilyl)methyl] triselenide (1) with copper occurs with formation of bis[tris(trimethylsilyl)-methyl] diselenide (2) and minor amounts of 3,3,5,5-tetrakis(trimethylsilyl)-1,2,4-triselenolane (3). The structures of 2 and 3 have been studied by multinuclear NMR spectroscopy and by X-ray crystallography. The C—Se—Se—C moiety of 2 adopts an unusual antiperiplanar conformation. Cleavage of the Se — Se bond by iodine providing iodo[tris(trimethylsilyl)-methyl]selane (5) is complete with 2, but reversible with 1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231215
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  • 6
    Electronic Resource
    Electronic Resource
    Synthese und Struktur von Lithiumkomplexen mit pentahapto-gebundenen, substituierten Cyclopentadienylliganden (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1449-1456 
    Details
    ISSN: 0009-2940
    Keywords: [Tris(trimethylsilyl)cyclopentadienyl]lithium complexes ; [Bis(trimethylsilyl)cyclopentadienyl]lithium complexes ; (Di-tert-butylcyclopentadienyl)lithium complexes ; Pentagonal-pyramidal cyclopentadienyllithium complexes ; (Tetrahydrofuran)[tris(trimethylsilyl)cyclopentadienyl]lithium, X-ray crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Lithium Complexes with Pentahapto-Bonded, Substituted Cyclopentadienyl LigandsThe reaction of [tris(trimethylsilyl)cyclopentadienyl]lithium, [bis(trimethylsilyl)cyclopentadienyl]lithium, and (di-tert-butylcyclopentadienyl)lithium with Lewis bases (ethers, amines, thioethers) leads to the crystalline, air-and moisture-sensitive adducts 1a-k, 2a-c, and 3a-c, which are monomeric in the solid state, in solution, and in the gas phase. The cyclopentadienyl ligand is pentahapto-bonded to the lithium atom. In the case of [tris(trimethylsilyl)cyclopentadienyl]lithium the use of monodentate ethers results in the isolation of complexes (1a-d, 1h, 1i) with an unusual coordination of the lithium ion. Thus, the crystal structure analysis of (tetrahydrofuran)[tris(trimethylsilyl)cyclopentadienyl]-lithium, [(Me3Si)3C5H2]Li · THF (1b), shows a nearly linear arrangement between the oxygen atom of the THF molecule, the lithium atom, and the ring centroid of the cyclopentadienyl ligand (Li—O = 187 pm; Li—Cp centroid = 180 pm).
    Notes: Die Umsetzung von [Tris(trimethylsilyl)cyclopentadienyl]lithium, [Bis(trimethylsilyl)cyclopentadienyl]lithium und (Di-tert-butylcyclopentadienyl)lithium mit Lewis-Basen (Ether, Amine, Thioether) führt zu kristallinen, sehr luft- und feuchtigkeitsempfindlichen Addukten 1a-k, 2a-c und 3a-c, die im Festkörper, in Lösung und in der Gasphase monomer vorliegen. Der Cyclopentadienylligand ist jeweils pentahapto an das Lithiumatom gebunden. Im Fall von [Tris(trimethylsilyl)cyclopentadienyl]lithium gelingt bei Verwendung von einzähnigen Ethern die Isolierung von Komplexen (1a-d, 1h, 1i) mit ungewöhnlicher Koordination des Lithum-Ions. So zeigt die Röntgenstrukturanalyse von (Tetrahydrofuran)[tris(trimethylsilyl)cyclopentadienyl]lithium, [(Me3Si)3C5H2]Li·THF (1b), eine nahezu lineare Anordnung zwischen dem Sauerstoffatom aus dem THF-Molekül, dem Lithiumatom und dem Ringzentrum des Cyclopentadienylliganden (Li—O = 187 pm; Li—Cp-Zentrum = 180 pm).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891220812
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  • 7
    Electronic Resource
    Electronic Resource
    Silicon Compounds with Strong Intramolecular Steric Interactions. LVIIPart LVI: Ref.[1].. Oxidation and Cycloaddition Reactions of an Unsymmetrically Substituted DisileneDedicated to Professor Manfred Regitz on the occasion of his 60th birthday. (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 935-939 
    Details
    ISSN: 0009-2940
    Keywords: Disilenes ; Organosilicon compounds ; 1,2,3-Oxadisiliranes ; Dioxadisiletanes ; Cycloaddition reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the unsymmetrically substituted disilene R2Si=SiR′2 (4; R = 2,4,6-Me3C6H2, R′ = 2,4,6-iPr3C6H2) with m-chloroperbenzoic acid (mCPBA) or oxygen furnished the correspondingly substituted 1,2,3-oxadisilirane 5 or 1,3,2,4-dioxadisiletane 6, respectively. The [2 + 2] and [2 + 4] Cycloaddition reactions of 4 with benzophenone and 3,5-di-tert-butyl-1,2-benzoquinone, respectively, proceeded with a high degree of regioselectivity to yield the 1,2,3-oxadisiletane 9 and the 2,3-dihydro-1,4,2,3-benzodioxadisiline 7. The latter product was isolated together with a small amount of an isomeric compound 8 in which the substituents at the silicon atoms are reversed. The molecular structures of the products 5, 6, and 7 were determined by X-ray crystallography.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280914
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  • 8
    Electronic Resource
    Electronic Resource
    Benzil Derivatives as Trapping Reagents for the Monomeric Alkylindium(i) Compound in-c(SiMe3)3 (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1269-1272 
    Details
    ISSN: 0009-2940
    Keywords: Indium ; Clusters ; Low-valent compounds ; Trapping reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetrahedral cluster compound tetrakis[[Tris(trimethylsilyl)methyl]indium(I)] 91) reacts in boiling n-hexane with benzil derivatives (p-X-C6H4)C(O)(p-X-C6H4) (X = H, OMe, Br), to yield the 1,4-cycloadditon products of the monomeric alkylindium(I), In-C(SiMe3)3, in which the In atoms are coordinated by a chelating enediolato ligand, to form a five-membered InO2C2 heterocycle. As shown by two crystal structure determinations (X = H, OMe), the products are dimeric in the solid state, with a four-membered In2O2 heterocycle in the molecular center and both C(SiMe3)3 groups, as well as both enediolato substitutents in a cis arrangement.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300915
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  • 9
    Electronic Resource
    Electronic Resource
    Stereoselectivity of the Transfer of Hydrogen Atoms to Cyclic Alkyl Radicals (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1069-1073 
    Details
    ISSN: 0009-2940
    Keywords: Free-radical additions ; Alkyl radicals ; Stereoselectivity ; Hydrogen transfer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of cyclohexane to alkylmaleic anhydrides 1a-f via cyclic radicals 2a-f gave a mixture of (Z)- and (E)-2,3-dialkylsuccinic anhydrides 3a-f. The stereoselectivity of the hydrogen transfer from cyclohexane to radicals 2a-d was measured in the temperature range of 200-260°C, and the relative activation parameters of the formation of (Z)- and (E)-3 were determined. The stereoselectivity of the hydrogen transfer from cyclohexylmercuric hydride at 25°C was measured as well. The results are rationalized assuming steric interactions in the transition state of H donor and β substituent and of α and β substituent, respectively. An X-ray structure analysis of the highly strained addition product (Z)-3d was performed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270616
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  • 10
    Electronic Resource
    Electronic Resource
    Siliciumverbindungen mit starken intramolekularen sterischen Wechselwirkungen, 47. Trisilacyclobutanimine (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 1043-1046 
    Details
    ISSN: 0009-2940
    Keywords: Trisilacyclobutanimines ; Cyclotrisilane, hexa-tert-butyl- ; Isocyanide insertion reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silicon Compounds with Strong Intramolecular Steric Interactions, 47[1]. - TrisilacyclobutaniminesTreatment of hexa-tert-butylcyclotrisilane (4) with aryl isocyanides leads to the trisilacyclobutanimines 5-8. Reaction of the 1,4-diisocyanobenzene derivative 7 with two molecules of 4 leads to the double insertion product 9, the X-ray structure analysis of which shows the Si3CN framework atoms to be almost exactly coplanar. The planes of the two four-membered rings are strictly parallel whereas the linking phenylene group forms a 71.67° angle with these planes. The most striking features of these and of related compounds are their dark colours with longest wavelength absorptions between 500 and 540 nm.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250510
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