A cationic rhodium(I)/(R)-Segphos (R) [(4A'-bi-1,3-benzo-dioxole)-5,5'-diylbis(diphenylphosphine)] complex catalyzes the highly enantioselective [4+2] annulation of 2-alkynyl-benzaldehydes with acyl phosphonates, leading to benzopyranones with a phosphonate-substituted quaternary carbon center in moderate to high yields with excellent ee's.