Synthesis of New Ligand 1,2-Bis { di[(R,R) -1,3,2-oxzaphosphlidine] phosphino} ethane with C₂ -symmetric Axis and Application in Rh-catalyzed Asymmetric Hydrogenation

New ligand 1,2-bis {di[(R,R)-1,3,2-oxzaphosphlidine] phosphino} ethane [(R, R)-BDOPPEs 1, 2, 3 and 4] with C₂-symmetric axis and bearing nitrogen and oxygen were synthesized from readily available optically active amino alcohols. Rh complexes with these ligands were highly enantioselective catalysts for asymmetric hydrogenation of N-benzoyldehydroamino acid derivatives and α-functionalized ketones in 99% e. e. and 98% e. e., respectively. This new class of (R,R)-BDOPPEs 1, 2, 3 and 4 gave much more effectivity and enantionselectivity than their corresponding non-C²-asymmetric aminophosphine phosphinite.