Rhodium-Catalyzed Enantioselective Cyclizations of γ-Alkynylaldehydes with Acyl Phosphonates: Ligand- and Substituent-Controlled C-P or C-H Bond Cleavage

It has been established that a cationic rhodium(I)/(R)-H-8-BINAP or (R)-Segphos complex catalyzes two modes of enantioselective cyclizations of gamma-alkynylaldehydes with acyl phosphonates via C-P or C-H bond cleavage. The ligands of the Rh(I) complexes and the substitutents of both gamma-alkynylaldehydes and acyl phosphonates control these two different pathways.