Unified Synthesis of Eudesmanolides, Combining Biomimetic Strategies with Homogeneous Catalysis and Free-Radical Chemistry

Abstract

[reaction: see text] A general procedure for the synthesis of both 12,6- and 12,8-eudesmanolides has been developed. The key step is the titanocene-catalyzed radical cyclization of accessible epoxygermacrolides. The novel reagent 2,4,6-trimethyl-1-trimethylsilylpyridinium chloride, both compatible with oxiranes and capable of regenerating Cp(2)TiCl(2) from Cp(2)Ti(Cl)H and Cp(2)Ti(Cl)OAc, played an important role in the catalytic cycle leading to exocyclic alkenes.