Synthesis of Isocoumarins from Cyclic 2‑Diazo-1,3-diketones and Benzoic Acids via Rh(III)-Catalyzed C–H Activation and Esterification

A mild and efficient Rh­(III)-catalyzed C–H activation/esterification reaction for the synthesis of isocoumarins has been developed. This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials and involves domino intermolecular C–H activation in combination with intramolecular esterification to give the corresponding isocoumarins in moderate to excellent yields. This process provides a facile approach for the construction of isocoumarins containing various functional groups that does not require any additives.