A Catalytic, Enantioselective Formal Synthesis of (+)-Dichroanone and (+)-Taiwaniaquinone H

A catalytic, enantioselective formal synthesis of (+)-dichroanone and (+)-taiwaniaquinone H is reported. The all-carbon quaternary stereocenter was constructed by asymmetric conjugate addition catalyzed by a palladium­(II) (S)-<i>tert</i>-butyl­pyridino­oxazoline complex. The unexpected formation of a [3.2.1] bicyclic intermediate required the identification of a new route. Analysis of the Hammett constants for <i>para</i>-substituted arenes enabled the rational design of a highly enantioselective conjugate addition substrate that led to the completion of the formal synthesis.