Asymmetric Reduction of Ketones

The enantioselective reduction of ketones to alcohols gives access to a pool of chiral building blocks that can be used for the synthesis of natural products. Adolfsson and co-workers reported a novel class of ligands, based on a pseudo-dipeptide,¹ for the mild and efficient reduction of ketones using 2-propanol as a hydrogen source. The ligand is used with [{RuCl₂(p-cymene)}₂] in presence of NaOH for the asymmetric reduction of a variety of acetophenone derivatives. Excellent yields and ee’s were reported (Scheme 1).