Phosphine-Catalyzed [3 + 2] Annulation of 2-Hydroxy-1,4-naphthaquinones and Allenoate: An Allene-Alkene [3 + 2] Annulation Mechanism Involving Consecutive γ-Addition-Aldol Reaction.

A diastereoselective construction of biologically important tetrahydrocyclopenta[ b]naphthalene derivatives has been achieved via a phosphine-catalyzed [3 + 2] annulation of 2-hydroxy-1,4-naphthaquinone derivatives and allenoate. Various tetrahydrocyclopenta[ b]naphthalene derivatives containing contiguous quaternary carbon centers are obtained in good yields with excellent diastereoselectivities. The asymmetric version gave the chiral product in up to 57% ee under catalysis of Kwon chiral phosphine. The reaction undergoes a reaction mechanism involving consecutive γ-addition-aldol reaction.