Kinetic Resolution of α‐Allyl‐α‐cinnamyl Carboxylic Acids Bearing an All‐Carbon Quaternary Stereocenter via Bromolactonization Catalyzed by a Chiral Bifunctional Sulfide

Catalytic kinetic resolutions of racemic carboxylic acids are important methods for preparing chiral carboxylic acids in their optically active forms. While several effective methods for the catalytic kinetic resolution of chiral α‐tertiary carboxylic acids have been reported, the efficient kinetic resolution of α‐quaternary carboxylic acids remains a significant challenge. In this context, we aimed to develop methods for the kinetic resolution of α‐quaternary carboxylic acids. Our approach involves a BINOL‐derived chiral bifunctional sulfide‐catalyzed bromolactonization technique, which was developed by our research group. In this work, we report the kinetic resolution of α‐allyl‐α‐cinnamyl carboxylic acids bearing an α‐quaternary stereocenter via chemo‐ and stereoselective bromolactonizations. The use of a BINOL‐derived chiral bifunctional sulfide catalyst with a hydroxy group was key for the efficient kinetic resolution of racemic α‐allyl‐α‐cinnamyl carboxylic acids.