Palladium(II)-Catalyzed Alkyne Annulation Reactions for the Synthesis of Cyclopenta[b]naphthalene-1,4-diones

Abstract A palladium-catalyzed C–H activation and alkyne annulation reaction of 2-hydroxy-3-(2-thienyl)naphthalene-1,4-diones has been developed for the construction of biologically important cyclopenta[b]naphthalene-1,4-dione derivatives. This reaction proceeds through hydroxy-group-directed heteroaryl C(sp2)–H activation, insertion of two molecules of an alkyne, and dehydrative cyclization pathways.