Synthesis of P-chirogenic diphosphine oxides and their use in catalytic asymmetric Diels–Alder reaction

New P-chirogenic phosphine oxides, (R,R)-1,2-bis(alkylmethylphosphinyl)ethanes (alkyl=1-adamantyl, tert-butyl) and (S,S)-1,1-bis(tert-butylmethylphosphinyl)methane have been synthesized from PCl3 via four steps. Their iron(III) complexes are effective in catalytic asymmetric Diels–Alder reaction of N-acrylamide dienophiles to provide enantioselectivities up to 75%.