Enantioselective Indole N-H Functionalization Enabled by Addition of Carbene Catalyst to Indole Aldehyde at Remote Site

An enantioselective functionalization of the indole NH group is developed. The reaction stereoselectivity is controlled by an N-heterocyclic carbene catalyst that adds to an aldehyde moiety at the C7-carbon of indole. The NH group participating in the carbene-catalyzed reaction is part of the heteroaromatic rings of the indole substrate. Our reactions afford multicyclic products bearing pyrroloquinazoline or oxazinoindole scaffolds widely present in bioactive molecules. Our study will encourage further exploration of carbene-catalyzed reactions of aromatic molecules and asymmetric transformation of heteroatoms in various functional molecules.