Iron-Catalyzed Radical [2 + 2 + 2] Annulation of Benzene-Linked 1,7-Enynes with Aldehydes: Fused Pyran Compounds

An iron-catalyzed radical [2 + 2 + 2] annulation of benzene-linked 1,7-enynes with aldehydes has been developed. With this method, a variety of fused [6.6.6] pyran molecules are built in an efficient and selective manner. The aldehydic radical-mediated strategy exhibits a particularly attractive dual role, which triggers and terminates the domino cyclization.