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  • 1
    Electronic Resource
    Electronic Resource
    2,5-Dihydro-1,2,5-azoniasilaboratole Derivatives - Useful Starting Materials in Heterocyclic Synthesis (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 147-153 
    Details
    ISSN: 0009-2940
    Keywords: 1,1-Organoboration ; 1-Alkynylsilanes ; 1,2,5-Azoniasilaboratoles, 2,5-dihydro-, organo-substituted ; Heterocyclic synthesis ; Multinuclear NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Alkynyl(diethylamino)dimethylsilanes [CC̊: R = Me (1a), nBu (1b), SiMe3 (1c)] react with triethylborane stereoselectively by 1,1-ethyloboration to give the alkenes with the boryl and silyl group in cis-positions at the C=C bond. Owing to the strongly intramolecular coordinative N-B bond, these products are 2,5-dihydro-1,2,5-azoniasilaboratoles (2a-c). Protic reagents such as azoles (indole, pyrazole, imidazole, triazole, indazole, benzotriazole) react with 2 to give diethylamine and the respective N-azolyl derivatives 3-8 which contain tetracoordinate boron in the case of 4-8. Compound 7, derived from indazole, was characterized by an X-ray analysis. With ethanol, the corresponding 2,5-dihydro-1,2,5-oxoniasilaboratoles 9 are obtained. Treatment of 2 with water affords 1,2,5-oxasilaborolanes 11, presumably via an intermediate 10 with the structure of a 2,5-dihydro-1,2,5-oxoniasilaboratole. All products were characterized by their 1H-, 11B-, 13C-, 15N-, and 29Si-NMR data.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290207
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  • 2
    Electronic Resource
    Electronic Resource
    Organo-Substituted 1,2-Dihydro-1,2,5-Disilaborepines (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1349-1352 
    Details
    ISSN: 0009-2940
    Keywords: Heterocycles ; 1,1-Organoboration ; Disilanes ; 1- Alkynylsilanes ; NMR spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Di-1-propynyl-tetramethyldisilan (1) reacts with triorganoboranes R3B [R = Et (2a), CH2Ph (2c), 2-thienyl (2d)], 9-ethyl-9-borabicyclo[3.3.1]nonane (3), and diethyl(N-pyrrolyl)borane (4) by twofold 1,1-organoboration to give selectively the respective organo-substituted 1,2-dihydro-1,2,5-disilaborepines 5a-d,6, and 7 in high yields. The compounds 5-7 were characterized by 1H-, 11B-, 13C-, and 29Si-NMR spectroscopy in solution. The molecular structures of the distance 1 and of the heterocycle 5c were determined by X-ray structure analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300928
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  • 3
    Electronic Resource
    Electronic Resource
    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
    Keywords: Tin cations ; triorgano ; Coordination ; s̰ and π ; 1,1-Organoboration ; 1-Alkynyltin compounds ; functionally substituted ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270209
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