title: Application of P-stereogenic aminophosphine phosphinite ligands in asymmetric hydroformylation
abstract: 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(PP)] complexes with the NP* moiety in an axial position are responsible for enantioselectivity.
authors.affiliation: Ciba, Division Additives AD 4.21, WS 2093.3.15, Pratteln 1, Switzerland.
authors.initials: R
authors.lastname: Ewalds
authors.initials: EB
authors.lastname: Eggeling
authors.initials: AC
authors.lastname: Hewat
authors.initials: PC
authors.lastname: Kamer
authors.lastname: van Leeuwen PW
authors.initials: D
authors.lastname: Vogt