Both ligands were developed by groups that included Weiping Chen; Trifer at StylaCats Ltd and ChenPhos at Solvias. These are P-P ligands for which a secondary interaction of the dimethylamino group with the substrate (electrostatic or hydrogen bonding) is invoked to account for the selectivity and activity observed. ChenPhos is a C1 symmetric variant of Trifer, the dicyclohexylphosphine (giving greater d-σ* interaction) imparting improved activity without loss of enantioselectivity. Applications to date resulting in >80% ee are principally with Rh, with one example of Ir catalysis.
Methodology also applied to geraniol to give (S)-citronellol, and nerol to give (R)-citronellol.
Absolute configuration not stated but assumed to be the same as Rh.