First Enantioselective Total Synthesis of (+)-Cortisone

Article abstract of DOI:10.1021/jo00308a022

The intramolecular <4 + 2> cycloaddition of an olefinic o-quinodimethane, having an optically active oxathiane system as a stereodirecting group, leads enantioselectively to A-nor B-aromatic steroids.This reaction is the key in an enantioselective total synthesis of (+)-cortisone (1).