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.