ABSTRACT
The desire to produce enantiomerically pure pharmaceuticals and other fine chemicals has advanced the field of asymmetric catalytic technologies. Since the independent discoveries of Knowles and Horner [1,2]; the number of innovative asymmetric catalysis for hydrogenation and other reactions has mushroomed. Initially, nature was the sole provider of enantiomeric and diastereoisomeric compounds; these form what is known as the ‘‘chiral pool.’’ This pool is comprised of relatively inexpensive, readily available, optically active natural products, such as carbohydrates, hydroxy acids, and amino acids, that can be used as starting materials for asymmetric synthesis [3,4]. Before 1968, early attempts to mimic nature’s biocatalysis through noble metal asymmetric catalysis primarily focused on a heterogeneous catalyst that used chiral supports [5] such as quartz, natural fibers, and polypeptides. An alternative strategy was hydrogenation of substrates modified by a chiral auxiliary [6].
