Application of P-Stereogenic Aminophosphine Phosphinite Ligands in Asymmetric Hydroformylation
摘要:
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%. H-1 and P-31 NMR studies of the Rh complexes under syngas pressure reveal that [HRh(CO)(2)((PP)-P-boolean AND)] complexes with the NP* moiety in an axial position are responsible for enantioselectivity.