Ru(II)-Catalysed Highly Regioselective C6 C-H/N-H Annulation of Indole-7-carboxamides with Alkynes for the Synthesis of Pyrrolo[3,2-h]isoquinolin-9-ones

We disclosed an efficient protocol for regioselective C6 C−H/N−H activation/annulation reaction of indole-7-carboxamides with alkynes to synthesize highly substituted pyrrolo[3,2-h]isoquinolin-9-one derivatives. Under optimized reaction conditions, electron-deficient and electron-rich internal alkynes reacted efficiently with various indole-7-carboxamides to deliver desired products in good to excellent yields. The synthetic utility of the product is demonstrated by its selective oxidation to the corresponding isatin derivative. Deuterium insertion and intermolecular competition experiments were also conducted to gain mechanistic insights.