When the triphenylphosphine ligands are replaced by chiral phosphines, the complex becomes chiral and converts prochiral alkenes into chiral alkanes with excellent enantioselectivity. For example, itaconic acid undergoes hydrogenation to give (S)-methylsuccinic acid with 95% ee in the presence of chiral CAPP-Rh(I) complex (Scheme 4).

Scheme 4

Likewise, 1-naphthyl methyl ketone enol acetate can be hydrogenated using Rh-diphospholane with 94% ee (Scheme 5).

Scheme 5

A similar result is obtained with the hydrogenation of N-acylaminoacrylic acids utilizing Rh-BINAP complex (Scheme 6).

Scheme 6

Likewise, the hydrogenation of ketopantolactone using Rh-(2S,4S)-BPPM can be accomplished with good enantioselectivity (Scheme 7).

Scheme 7