Rhodium(II) perfluorobutyrate catalyzed silane alcoholysis. A highly selective route to silyl ethers

Rhodium (II), perfluorobutyrate, Rh 2 (pfb) 4 , is an effective catalyst for the alcoholysis of trialkylsilanes at room temperature. Primary alcohols react with triethylsilane approximately 5 times faster than do secondary alcohols, and tertiary alcohols are virtually inert. Enhanced selectivity is achieved with tert-butyldimethylsilane. Hydrosilylation of olefinic alcohols is relatively unimportant even with terminal alkenes, but Rh 2 (pfb) 4 does promote hydrogenation of 3-phenyl-2-propen-1-ol. Selected diols have been silylated with complete regioselectivity in Rh 2 (pfb) 4 -catalyzed reactions with either triethylsilane or tert-butyldimethylsilane. Methanolysis of (S)-(−)-1-naphthylphenylmethylsilane occurs with nearly complete inversion of configuration at silicon, and spectral analysis of the catalytic reactions suggests a mechanism for silane alcoholysis in which the rhodium (II) catalyst coordinates with the silicon hydride to activate silicon for backside nucleophilic attack by the alcohol