ChemInform Abstract: The Reaction of Trimethylsilyl Ethylene Oxide with α-Sulfonyl Anions and α,α-Sulfonyl Dianions. A Method for Stereocontrolled Synthesis of (E)- and (Z)-Allylic Alcohols.

Abstract

Abstract Trimethylsilyl ethylene oxide has been shown to react with α-sulfonyl carbanions generated from representative primary alkyl phenyl sulfones to give the corresponding O-trimethylsilyl allylic alcohols, with higher selectivity of (Z)-isomers. The reaction proceeds by attachment of the nucleophile to the α-position of the α,β-epoxyalkylsilane followed by a carbon-to-oxygen shift to the trimethylsilyl group and expulsion of the benzenosulfonyl anion. The reaction of trimethylsilyl ethylene oxide with α,α-sulfonyl dianions followed by partial protonation of the immediate adducts affords O-trimethylsilyl allylic alcohols, mainly (E)-isomers. The reaction of trimethylsilyl ethylene oxide with α-sulfonyl carbanions generated from secondary alkyl phenyl sulfones affords α-trimethylsilyl carbinols as the only or predominant product. In this case the attachment of the nuclephile takes place at the β-position of the α,β-epoxyalkysiane. The origin of the regio- and stereo-selectivity in reactions of sulfonyl carbanions with α,β-epoxyalkylsilanes is discussed.