The Diels-Alder reaction of 1,4-quinones in hexafluoroisopropanol

The Diels-Alder reaction of quinones is both of historical and current importance, and numerous asymmetric and catalytic versions have been described. Herein we describe the dramatic rate enhancement observed in the Diels-Alder reactions of a large variety of quinones with moderately activated dienes when hexafluoroisopropanol is used as a solvent, even allowing reactions that are not observed in dichloromethane. When chiral sulfinylquinones are used, hexafluoroisopropanol has a marked effect on stereoselectivity. Since the Diels-Alder reactions of sulfinylquinones are known to be an entry into several classes of natural products, and many other quinone cycloadditions have found wide-spread use in synthesis, the findings described will further facilitate their application