Iron‐Catalyzed Synthesis of Indenones through Cyclization of Carboxamides with Alkynes

The iron/diphosphine‐catalyzed annulation of a carboxamide possessing a bidentate directing group with an internal alkyne proceeds in the presence of phenylzinc halide as a base at 40 °C to produce a variety of indenone derivatives. The reaction proceeds through iron‐catalyzed C−H bond activation of the carboxamide, followed by insertion of the alkyne into the resulting iron intermediate, and cyclization accelerated by the presence of Lewis acidic Zn II . The reaction of naphthalene and anthraceneamide yields π‐conjugated indenone derivatives.