R. Calas

Stereospecific Synthesis and Acylation of cis 1-Halo 2-Trimethylsilyl Ethylenes

Abstract Several routes to 1-halo 2-trimethylsilyl ethylenes have been previously proposed 1-6: from ethyn7yltrimethylilane (addition of HBr1,2), ethyltrichlorosilane (addition H by C1, followed by dehydrohalogenation and further methylation of th Si-C1 bonds)3 or by other ways 4,5, especially by reaction of (2-trimethylsilyl) vinyl lithium with dibromoethane6.

Sulfonation d'alcynes siliciés et synthèse d'acides sulfoniques α-acetylèniques

Abstract The sulfonation of α-silylalkynes R′-CCSiR3 under standard conditions yields different unsaturated sulfonic compounds, depending on the starting materials: SO3 triple bond adducts or silyl α-acetylenesulfonates R′CCSO3SiR3. Hydrolysis of these latter compounds gives, when R′ is a trialkylsilyl or tert-butyl group, the corresponding α-acetylenesulfonic acids, which as far as we know, have not yet been reported. A mechanism of these sulfonation reactions is proposed.

Nouvelles méthodes de création de la liaison siliciumcarbone à partir de chlorosilanes XI. Essais de silylation de nitriles α-éthyléniques

Abstract In the presence of magnesium and with a basic solvent such as hexamethylphosphoric triamide, trimethylchlorosilane reacts with cinnamonitrile and leads to the 1,2-addition compound with respect to the nitrile group. 1,2-Bis(dimethylchlorosilyl)ethane gives a similar disilylation. By reaction with methylmagnesium iodide and after hydrolysis, 3-phenyl-2,3-bis(trimethylsilyl)propionitrile (I) gives 1-phenyl-1-(trimethylsilyl)-3-butanone which may be obtained by silylation of benzylideneacetone according to the same process. In presence of aluminium chloride, (I) is converted quantitatively in 3-phenyl-3-(trimethylsilyl)propionitrile. In similar conditions, crotonotrile leads to a reductive duplication without SiC bonding synthesis. A mechanism is proposed for these reactions.

Synthese directe du trimethylsilylmethanol par c-silylation du formaldehyde☆

Abstract Direct C-silylation of formaldehyde by the Me 3 SiCl/Li/THF reagent affords Me 3 SiCH 2 OSiMe 3 upon hydrolysis leads to Me 3 SiCH 2 OH, which previously wastedious to prepare. Such a reaction is the first example of direct C-silylation of a functional compound having one carbon atom.

A simple, new preparation of α,α-dimethylallyltrimethylsilane: a useful prenylation reagent

Starting from 3-methylbut-1-yn-3-ol, a short synthesis of αα-dimethylallyltrimethylsilane (a selective prenylation reagent) has been achieved in 47% overall yield; several other unsaturated organosilicon intermediates of wide potential utility in organic synthesis are also prepared.

Nouvelle méthode de préparation d'hydrogénosilanes à partir de chlorosilanes

Abstract We have synthetized hydrogenosilanes by an original process: action of chlorosilanes on magnesium with gaseous hydrogen chloride, ammonium chloride or tertiary amines hydrochlorides in hexamethylphosphoric triamide (HMPT) medium. By this way we have obtained mono- or polyhydrogenosilanes with good yields (French Patent application June 16th, 1969).

Nouvelles syntheses de Me2SiCl2 et Me3SiCl

Abstract Partial reduction of MeSiCl 3 and Me 2 SiCl 2 using CaH 2 or (TiH 2 ) n at high temperature (300°C) leads to MeSiHCl 2 and Me 2 SiHCl, respectively, in good yields but in low proportion. In the presence of AlCl 3 as catalyst the reaction affords Me 2 SiCl 2 and Me 3 SiCl, in yields higher than those previously observed in the absence of a reducing agent. These redistribution reactions involve MeSiHCl 2 and Me 2 SiHCl as intermediates. Consequently Me 2 SiHCl with or without Me 2 SiCl 2 and Alcl 3 deposited on carbon black as catalyst can undergo disproportionation to give Me 3 SiCl.

One-step synthesis of dodecamethylcyclohexasilane

Dodecamethylcyclohexasilane (Me2Si)6 has been conveniently prepared from Me2SiCl2 and Li, in tetrahydrofuran at 0°C.