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.

Transition metal-free catalysts, i.e. organocatalysts such as the CBS catalyst based on proline used to ketones are known as well.