Radical Cyclization of (Bromomethyl)dimethylsilyl Propargyl Ethers; III. Stereoselective Hydrogen Abstraction of Trisubstituted Vinyl Radicals. Application to a Terpenoid Building Block Synthesis¹

Abstract

Trisubstituted olefins have been obtained via stereoselective hydrogen abstraction by vinyl radicals, prepared by the radical cyclization of (bromomethyl)dimethylsilyl propargyl ethers. Application to the stereoselective synthesis of the terpenoid building block (Z)-2-methyl-7-(2-tetrahydropyranyloxy)-3-(trimethylsilylmethyl)-3-hepten-2-ol, prepared by the radical cyclization of 2-[(bromomethyl)dimethylsiloxy)-2-methyl-7-(2-tetrahydropyranyloxy)-3-heptyne, is given to illustrate the methodology.