Stereoselective synthesis of allyl ethers using α,β-unsaturated acylsilanes

Abstract

The reaction behavior of silylvinylmethanols with acid catalysts was investigated. The starting silylvinylmethanols 2 were prepared by the reaction of the corresponding α,β-unsaturated acylsilanes 1 with organocerium reagents. The reaction of 2 with TsOH in methanol proceeded to give the corresponding silyl-substituted allyl ether derivatives 3 in high yields with good stereoselectivity. The silylvinylmethanols 2 having a n-alkyl or phenyl group on the carbinyl carbon reacted to afford the E-allyl derivatives selectively. On the other hand, the reaction of silylvinylmethanols possessing a tert-butyl group gave the Z-isomers exclusively. The following protodesilylation of the resulting allyl derivatives 3 proceeded with retention of configuration to provide the geometrically constrained allyl ethers 4.