1,4-Iron Migration for Expedient Allene Annulations through Iron-Catalyzed C−H/N−H/C−O/C−H Functionalizations

Abstract

Abstract C−H activation bears great potential for enabling sustainable molecular syntheses in a step‐ and atom‐economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C−H/N−H/C−O/C−H functionalization sequence. The powerful iron catalysis occurred under external‐oxidant‐free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4‐iron migration regime for facile C−H activations.