The application of enantioselective catalysts in the pharmaceutical and agrichemical industries has increased rapidly over the last two decades. The trauma associated with the use of racemic thalidomide led regulatory agencies to demand vigorous justification for approval of the use of a racemate in products for biological work. The work of W.S. Knowles et al. showed that the use of a homogeneous organometallic compound with a chiral ligand could give product of sufficient optical purity (> 95%) to be economically attractive. The development was based on the use of the homogeneous hydrogenation catalyst of Wilkinson [RhC 1(PO3)3], replacing triphenyl phosphine with optically active phosphorus, to reduce a prochiral olefin. The high optical purity product results in greatly reduced investment in synthesis and purification, which compensates for the expense of the catalyst, which further contributes a catalyst multiplier factor.