Controlled carbon–sulphur or carbon–silicon bond cleavage in the reactions of alkyl-lithium reagents with a 1-silyl-1-thioallene

Abstract

3-Methyl-1-phenylthio-1-trimethylsilylbuta-1,2-diene (3) reacts with different alkyl-lithium reagents by C–Si or C–S bond cleavage, rather than by Michael addition or metallation; one product, the α-silyl-α-lithioallene (6), is alkylated mainly γ with carbonyl compounds, but is silylated α with Et₃SiCl to from the 1,1-bis-silylallene Me₂CCC(SiEt₃)SiMe₃.