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Synthesis of silyl substituted organoboranes by hydroboration of vinylsilanes

Ruwisch, Lutz M. and Dürichen, P. and Riedel, R. :
Synthesis of silyl substituted organoboranes by hydroboration of vinylsilanes.
In: Polyhedron, 19 (3) pp. 323-330.
[Article] , (2000)

Abstract

Hydroboration reactions of dichloroborane-, monochloroborane- and borane-dimethylsulfide with dichloromethylvinylsilane and trichlorovinylsilane were investigated. The proposed structures of the produced organochlorosilylboranes 1–4 were verified by NMR spectroscopic measurements and in the case of [α-(dichloromethylsilyl)ethyl]dichloroborane-dimethylsulfide (4) the molecular structure was determined by single-crystal X-ray diffraction (L.M. Ruwisch, R. Riedel, U. Klingebiel, M. Noltemeyer, Z. Naturforsch., Teil B 54 (1999) 624). Following the Markovnikov rule, the first addition appears strictly regioselective in the α-position to silicon, producing one chiral methine group between silicon and dichloroborane in compound 4. The second addition of borane- or monochloroborane-dimethylsulfide at the vinyl groups of dichloromethylvinylsilane and trichlorovinylsilane also takes place in the α-position to silicon, forming a second chiral methine group. In the case of borane-dimethylsulfide the third addition occurs in the β-position (anti-Markovnikov) owing to steric hindrance to boron in tris[(dichloromethylsilyl)ethyl]borane (1). A stepwise substitution of chlorine bonded at boron in compounds 2 and 3 using hexamethyldisilazane produces bis[α-(dichloromethylsilyl)ethyl]boryl-trimethylsilylamine (5) and bis[α-(trichlorosilyl)ethyl]boryl-trimethylsilylamine (6), respectively, under release of chlorotrimethylsilane. The remaining trimethylsilylamine group in 6 can be replaced by further reaction with 3 forming tetrakis[α-(trichlorosilyl)ethyl]diborylamine (7). This reaction resembles a selective amino condensation at boron. In a similar condensation reaction of 4 with equivalent amounts of hexamethyldisilazane, tris[α-(dichloromethylsilyl)ethyl]borazine (8) can be obtained.

Item Type: Article
Erschienen: 2000
Creators: Ruwisch, Lutz M. and Dürichen, P. and Riedel, R.
Title: Synthesis of silyl substituted organoboranes by hydroboration of vinylsilanes
Language: English
Abstract:

Hydroboration reactions of dichloroborane-, monochloroborane- and borane-dimethylsulfide with dichloromethylvinylsilane and trichlorovinylsilane were investigated. The proposed structures of the produced organochlorosilylboranes 1–4 were verified by NMR spectroscopic measurements and in the case of [α-(dichloromethylsilyl)ethyl]dichloroborane-dimethylsulfide (4) the molecular structure was determined by single-crystal X-ray diffraction (L.M. Ruwisch, R. Riedel, U. Klingebiel, M. Noltemeyer, Z. Naturforsch., Teil B 54 (1999) 624). Following the Markovnikov rule, the first addition appears strictly regioselective in the α-position to silicon, producing one chiral methine group between silicon and dichloroborane in compound 4. The second addition of borane- or monochloroborane-dimethylsulfide at the vinyl groups of dichloromethylvinylsilane and trichlorovinylsilane also takes place in the α-position to silicon, forming a second chiral methine group. In the case of borane-dimethylsulfide the third addition occurs in the β-position (anti-Markovnikov) owing to steric hindrance to boron in tris[(dichloromethylsilyl)ethyl]borane (1). A stepwise substitution of chlorine bonded at boron in compounds 2 and 3 using hexamethyldisilazane produces bis[α-(dichloromethylsilyl)ethyl]boryl-trimethylsilylamine (5) and bis[α-(trichlorosilyl)ethyl]boryl-trimethylsilylamine (6), respectively, under release of chlorotrimethylsilane. The remaining trimethylsilylamine group in 6 can be replaced by further reaction with 3 forming tetrakis[α-(trichlorosilyl)ethyl]diborylamine (7). This reaction resembles a selective amino condensation at boron. In a similar condensation reaction of 4 with equivalent amounts of hexamethyldisilazane, tris[α-(dichloromethylsilyl)ethyl]borazine (8) can be obtained.

Journal or Publication Title: Polyhedron
Volume: 19
Number: 3
Publisher: Elsevier
Uncontrolled Keywords: Hydroboration, Polysilazanes, Precursors, Vinylsilanes, Chloroboranes
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 19 Nov 2008 15:55
Funders: We gratefully acknowledge financial support of the DFG (Deutsche Forschungsgemeinschaft/Bonn) and the Fonds der Chemischen Industrie (Frankfurt Germany).
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