Pd-Catalyzed C–H Carbonylation of (Hetero)arenes with Formates and Intramolecular Dehydrogenative Coupling: A Shortcut to Indolo[3,2‑<i>c</i>]coumarins

An efficient protocol for the synthesis of (hetero)­aryl carboxylic esters has been achieved by Pd-catalyzed C–H carbonylation of (hetero)­arenes with aryl formates. A relatively wide range of functional groups can be tolerated in this transformation, and the corresponding esters are obtained in good yields. On this basis, an intramolecular oxidative C–H/C–H coupling has been developed to prepare indolo­[3,2-<i>c</i>]­coumarins.