Ruthenium-Catalyzed Oxidative Annulation and Hydroarylation of Chromene-3-carboxamides with Alkynes via Double C–H Functionalization

Ruthenium-catalyzed oxidative annulation of 2H-chromene-3-carboxamides with alkynes has been achieved by using the directing group nature of amide in the presence of Cu­(OAc)2·H2O as an oxidant and AgNTf2 as an additive. This reaction offers a broad substrate scope, and both symmetrical and unsymmetrical alkynes can be harnessed. High regioselectivity was achieved in the case of unsymmetrical alkynes. In addition, we have also accomplished double C–H activation by employing an excess of alkyne, where both annulation and hydroarylation took place regio- and stereoselectively in one pot, with the catalyst playing a dual role. While the first C–H functionalization could involve Ru–N covalent bond, the second C–H functionalization most likely involves Ru–O coordinate bond. The structures of key products are confirmed by X-ray crystallography.