Facile syntheses of α-bromo-α-silyl ketones and α-bromoacylsilanes from tert-butyldimethylsilyldibromomethane and carbonyl compounds

Abstract

An addition of benzaldehyde to an ethereal solution of tert-butyldimethylsilyldibromo-methyllithium, derived from t-BuMe 2SiCHBr 2 and lithium diisopropylamide, provided α-bromo-α-silyl ketone. The use of ketone instead of aldehyde afforded α-bromoacylsilane via a bromo silyl epoxide intermediate. Further treatment of the α-bromo-α-silyl ketone with butyllithium afforded lithium enolate which provided β-hydroxy-α-silyl ketone upon treatment with aldehyde in ether. The enolate gave α,β-unsaturated ketone or monosilyl ether of 2-acyl-1,3-diol in THF instead of ether. The use of isopropylmagnesium bromide in place of butyllithium also resulted in a formation of the corresponding magnesium enolate.