An Intramolecular Diels-Alder Strategy for the Asbestinins : Enantioselective Total Syntheses of 11-Acetoxy-4-deoxyasbestinin D and Asbestinin-12

The enantioselective total syntheses of 11-acetoxy-4-deoxyasbestinin D and asbestinin-12 have been completed. A glycolate aldol reaction provided a diene useful for ring-closing metathesis to form an oxonene, which was ultimately employed as a template to execute a highly stereoselective intramolecular Diels−Alder cycloaddition, forming the hydroisobenzofuran moiety. The absolute configuration of the asbestinin subclass was confirmed via these synthetic efforts.