CHEMISTRY OF SILOLES. THE REACTIONS OF SILOLES WITH ORGANOLITHIUM REAGENTS

Article abstract of DOI:10.1016/0022-328X(83)85043-8

The chemical behaviour of siloles toward various organolithium reagents in THF has been investigated.The reaction of 1-methyl-1-(trimethylsilyl)-, 1-phenyl-1-(trimethylsilyl)- and 1,1-bis(trimethylsilyl)dibenzosilole(I, II and III) with a large excess of an alkyllithium such as methyllithium or butyllithium afforded 1,1-dialkyldibenzosiloles in quantitative yields.Treatment of I with an excess of phenyllithium gave a mixture of 1-methyl-1-phenyl- and 1,1-diphenyldibenzosilole quantitatively, while with an excess of tert-butyllithium, I afforded 1,1-dimethyl and 1-tert-butyl-1-methyldibenzosilole in low yield.Similar treatment of I and II with 1 equiv. of methyl- or butyl-lithium yielded a mixture of the corresponding mono- and dialkyl-substituted dibenzosiloles. 1-Methyl-3,4-diphenyl-1,2,5-tris(trimethylsilyl)silole reacted with methyllithium in THF to give 1,1-dimethyl-3,4-diphenyl-2,2,5-tris(trimethylsilyl)silole.Similarly, both 2,4-diphenyl-1,1,3,5-tetrakis(trimethylsilyl)silole and 4,5-diphenyl-1,1,2,3-tetrakis(trimethylsilyl)silole with methyllithium afforded two isomers of 1-methyl-2,4-diphenyl-1,2,3,5-tetrakis(trimethylsilyl)-1-silacyclopent-3-ene in a ratio of 3:2 in high yields.