Junichi Kondo

Reactions of gem-dibromo compounds with trialkylmagnesate reagents to yield alkylated organomagnesium compounds.

The reaction of gem-dibromocyclopropanes 5 with nBu(3)MgLi affords butylated cyclopropylmagnesium species that can be trapped with various electrophiles. The reaction of dibromomethylsilanes 12 requires the addition of a catalytic amount of CuCN small middle dot2 LiCl for smooth migration of the alkyl groups. The resultant alpha-silylpentylmagnesium compounds 16 react with electrophiles, such as acyl chlorides or alpha,beta-unsaturated ketones to afford alpha- or gamma-silyl ketones, respectively. Treatment of dibromodisilylmethanes with Me(3)MgLi yields 1-bromo-1,1-disilylethanes 25 that can be converted into 1,1-disilylethenes 29 by dehydrobromination.

Alkylative Preparation ofα-Silylalkylmagnesium from R3SiCHBr2 Using a Magnesate Reagent

Magnesium-bromine exchange to provide the 1-bromo-1-silylmethylmagnesium species is mediated by treatment of dibromomethylsilane with an trialkylmagnesate reagent. The addition of a copper catalyst induces facile migration of an alkyl group to afford an α-silylalkylmagnesium compound, which furnishes α-silyl ketones in good yield upon treatment with acyl chloride.

Generation and regioselective reactions of α,α-bis(silyl)-substituted allylcopper reagents—synthesis of 1,1-disilylalkenes

Abstract Treatment of chlorobis(methyldiphenylsilyl)methyllithium with vinylic Grignard reagents and CuCN·2LiCl afforded α,α-bis(silyl)-substituted allylic copper species. The reactions of the reagents with electrophiles provided a variety of 1,1-disilylalkenes.

Facile synthesis of ketones from 1,1-disilylethenes via oxidation of gem-disilylalkanes

The oxidation of gem-disilylalkanes, which can be derived from 1,1-disilylethene, alkyllithiums and alkyl halides, affords the corresponding ketones.