Synthesis of novel organosilicon compounds possessing highly substituted imidazole core catalyzed by antimony trioxide.

A general synthetic route for the exclusive preparation of tetrasubstituted imidazoles, possessing benzylic methyl groups has been developed using Sb2O3 via solvent-free, one-pot reaction conditions. Detailed results from our investigation on the bromination of the benzylic methyl groups of imidazoles are described. The products generated during this study were utilized as substrates for the synthesis of organosilicon-containing imidazoles. Synthesis of tris(triorganosilyl)methylimidazole derivatives was carried out using organolithium reagents (RSiMe2)3CLi, (R= H, Me, Ph) prepared via metalation of (RSiMe2)3CH with lithiumdiisopropylamide or methyllithium in THF, in excellent yields. (RSiMe2)3CLi, (R= Me, Ph) were treated with formylated imidazole to afford imidazole containing 2,2-bis(organosilyl)ethenyl groups. 2-(4-(2,2-bis(trimethylsilyl)vinyl)phenyl)-1,4,5-triphenyl-1H-imidazole was obtained via Peterson reaction in high yield. However, compound 2-(4-(2,2-bis(dimethyl(phenyl)silyl)vinyl)phenyl)-1,4,5-triphenyl-1H-imidazole was obtained in low yield likely because of the steric hindrance of the (PhSiMe2)3C- group.