In the process of developing an enantioselective [2+2] photocycloaddition of vinylpyridines, Steven and Wes discovered stereochemical cooperativity between a chiral Brønsted acid catalyst and a chiral Ir photocatalyst. It’s a gratifying demonstration that matched/mismatched effects are just as important in excited-state reactions as in classical ground-state reactions. Thanks also to Christine Le and Dean Toste for access to their large library of stereochemically diverse chiral Brønsted acids!
