Catalytic Atroposelective Coumarin Alkenylation.

A novel atroposelective alkenylation of coumarins, accomplished through palladium-catalyzed dehydrogenative coupling facilitated by a transient directing group strategy, has been presented. The optimized protocol exhibits a broad scope, as demonstrated by a diverse series of examples, highlighting its versatility and efficiency in the synthesis of atropisomeric coumarin analogues. Successful scale-up synthesis further illustrates the practical application of this method. The robustness and synthetic utility were validated through classical transformations, underscoring its effectiveness. This work introduces an unprecedented approach for the construction of axially chiral aryl lactones, especially coumarins, showcasing the effectiveness of transient directing groups in palladium-catalyzed chemistry.