Ring Expansions of β-Keto Lactones with Zinc Carbenoids: Syntheses of (+)-Patulolide A and (±)-Patulolide B

Abstract
A one-pot ring expansion/oxidation/elimination method has been developed in which β-keto lactones are converted efficiently to α,β-unsaturated-γ-keto lactones. The reaction can be successfully applied to a variety of ring sizes. Alkene stereochemistry is dependent upon ring size and reaction conditions. The method was applied to the synthesis of (+)-patulolide A.