Application of P-stereogenic aminophosphine phosphinite ligands in asymmetric hydroformylation

Article abstract of DOI:10.1002/(SICI)1521-3765(20000417)6:8<1496::AID-CHEM1496>3.0.CO;2-8

New chiral aminophosphine phosphinite ligands with a stereogenic center at the aminophosphine phosphorus atom were prepared based on (R,S)-ephedrine as the chiral auxiliary and backbone. Substituents at the chiral aminophosphine as well as at the phosphinite phosphorus atom were varied. These new ligands were applied to the rhodium-catalyzed asymmetric hydroformylation of vinyl arenes. The enantiomeric excess reached up to 77%. ¹H and ³¹P NMR studies of the Rh complexes under syngas pressure reveal that [HRh(CO)₂(P/P)] complexes with the NP* moiety in an axial position are responsible for enantioselectivity.