Asymmetric catalytic reduction
Asymmetric catalytic reduction is the use of various chiral catalysts to reduce a prochiral organic compound to obtain a chiral product. This is one of the several techniques used in chiral synthesis.
Typically, a transition metal is used with a bulky chiral ligand to such that the substrate molecule can only approach in a particular orientation. This causes an external reductant to reduce the substrate in a predictable fashion. Well-known examples include Knowles' ruthenium-based catalyst, similar to Wilkinson's catalyst, which reduces alkenes, and Noyori asymmetric hydrogenation catalysts using chiral BINAP ligands and dihydrogen to reduce ketones and alkenes.