Stereospecific formation of optically active trialkylsilyllithiums and their configurational stability

Optically active trialkylsilyllithiums, (R)-(n-butyl)methylphenylsilyllithium (63% ee) and (S)-methyl(1-naphthyl)phenylsilyllithium (96% ee), were prepared by cleavage of the siliconsilicon bond of (R)-1-(n-butyl)-1-methyl-1-phenyl-2,2-diphenyl-2-methyldisilane with lithium metal, or the silicontin bond of (S)-methyl(1-naphthyl)phenylsilyltrimethylstannane with methyllithium, respectively. Optical purity of the silyllithiums was evaluated as corresponding silanes by HPLC on optically active stationary phase after hydrolysis. The formation of silyllithium was found to be highly stereospecific (>94, >99% retention, respectively). (S)-Methyl(1-naphthyl)phenylsilyllithium is configurationally stable for at least 1 h at −78°C in tetrahydrofuran.