Chiral Bifunctional Sulfide-Catalyzed Enantioselective Synthesis of α-Substituted γ-Lactones Bearing a γ-Quaternary Stereocenter

Catalytic highly enantioselective syntheses of α-spiro-γ-lactones and α-substituted γ-lactones bearing a γ-quaternary stereocenter have been achieved via chiral bifunctional sulfide-catalyzed asymmetric bromolactonizations. The synthetic utility of the optically active γ-lactone products was demonstrated in the transformations to functionalized γ-lactones and epoxides possessing a quaternary stereocenter.