THE REACTION OF O-SILYLATED α-KETOLS WITH TRIMETHYLSILYL CYANIDE

Abstract

The reactions of a series of O-silylated α-ketols with trimethylsilyl cyanide have been investigated. Formation of the expected 0-trimethylsilyl cyanohydrins as major products has been shown to be accompanied by the hitherto unsuspected formation of a disiloxane by a proposed intramolecular S_N2 displacement mechanism. The latter reaction is, surprisingly, independent of the substitution pattern in the silylated ketol. Formation of the side-product, however, increases in all cases with increasing dilution. The α,β-epoxynitrile 9, a second side-product expected, along with the observed disiloxane, by our proposed mechanism was synthesized by an unambiguous route. A control experiment showed the epoxynitrile to be completely destroyed under the usual conditions of reaction with trimethylsilyl cyanide. ¹³C NMR data have been obtained for most of the compounds in this study.

Key Words:

• trimethylsilyl cyanide
• α-ketols (O-silylated)
• α,β-epoxynitrile
• disiloxane