The concise synthesis of axially chiral biaryl diphosphine ligands I (5a, R = Ph, Z = electron pair) by the rhodium-catalyzed intramol. [2 + 2 + 2] cycloaddn. of hexayne diphosphine oxides has been achieved. Rhodium-(S)-tol-BINAP-catalyzed [2+2+2] intramol. cycloaddn. of diphosphinyl-substituted hexayne triethers Ar2P(O)C竕｡CCH2OCH2C竕｡CCH2OCH2C竕｡CC竕｡CCH2OCH2C竕｡CCH2OCH2C竕｡CP(O)Ar2 (3a-c; Ar = Ph, 4-MeC6H4, 3,5-Me2C6H3) gave phosphine oxides (R)-I (4a-c, Z = O) with 92-85% ee and 48-15% yields. After recrystn. the oxide 4a was recovered with >99% ee, and reduced to bis(diphenylphosphino) ligand I (5a, R = Ph, Z = lone pair). Asym. hydrogenation of 2-acetamidoacrylate, di-Me itaconate and N,N,2-triphenylacrylamide CH2:CPhCONPh2 catalyzed by 5a, gave the corresponding products with 98%, 78% and 48% ee, compared to 25-18% ee in reaction catalyzed by Rh-BINAP complex. [on SciFinder(R)]
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