ABSTRACT
A review is presented of recent studies directed toward catalytic asymmetric hydrogenation of prochiral imines. The homogeneous systems are dominated by ones based on Rh complexes with chiral, phosphorus-containing ligands, although related Ru- and Ir-based systems are known; one, fundamentally different, early transition-metal catalyst (a chiral titanocene) has been reported. Enantiomeric excess (e.e.) values of >90% have been achieved with certain substrates. Emphasis is given to some Rh and Ru catalysts developed in this department at UBC. Factors discussed include: dependence of conversions, rates, and e.e. values on substrate and catalyst type, kinetic dependences, and mechanistic insights, especially possible roles of intermediate metal-hydride and -imine species.
