Double Annulation of ortho- and peri-C−H Bonds of Fused (Hetero)Arenes to Unusual Oxepino-Pyridines

Direct difunctionalization of chemically distinct ortho- and peri-C−H bonds of fused hetero(arenes) is illustrated through an unusual one-pot domino {[4+2] & [5+2]} double annulation with alkynes for the first time. This process is viable under Ru(II)-catalysis using a sulfoximine directing group and builds four bonds [(C−C)-(C−N) and (C−C)-(C−O)] in a single operation. Such synthetic manifestation offers access to uncommon [6,7]-fused oxepino-pyridine skeletons. DFT calculations provide mechanistic insight into this double annulation of naphthoic acid derivatives with alkynes and corroborate the participation of a ruthena-oxabicyclooctene intermediate, which is responsible for the rare 7-membered ring formation.