Silver-Mediated Radical Cyclization of Alkynoates and α‑Keto Acids Leading to Coumarins via Cascade Double C–C Bond Formation

A novel and convenient silver-mediated radical cyclization method for the synthesis of coumarin derivatives via the direct difunctionalization of alkynoates with α-keto acids through double C–C bond formation under mild conditions has been developed. This new method is highly efficient and practical, and the starting materials are readily prepared. The present method should provide a useful strategy for the construction of coumarin motifs.