α-Xanthyl Cyclopentenones and Cyclohexenones: New, Highly Versatile Building Blocks

A versatile strategy to synthesize α,β-functionalized cyclopentanones and cyclohexanones is described. It takes advantage of new reagents, α-xanthyl enones, which can be prepared from the reaction of xanthate salts with epoxides under acidic conditions. β-Functionalization of these compounds can be performed by conjugate additions without affecting the xanthate moitety. This significantly expands the pool of xanthate substrates, allowing the synthesis of open chain and fused bicyclic building blocks useful in the synthesis of natural products.