Asymmetric Diels−Alder Reactions of a New Enantiomerically Pure Sulfinylquinone:  A Straightforward Access to Functionalized Wieland−Miescher Ketone Analogues with (R) Absolute Configuration

An efficient and highly stereocontrolled preparation, on a large scale, of two new Wieland−Miescher-type diketones is described. The approach centers on a diastereoselective Diels−Alder reaction using a new enantiomerically pure sulfinylquinone. Mechanistic investigations of this cycloaddition on several dienes are described.