Enantioselective reduction of aliphatic ketones using NaBH4 and TarB–NO2, a chiral boronic ester

High enantioselectivities are obtained using a tartaric acid-derived boronic ester (TarB–NO2) in combination with NaBH4 for the asymmetric reduction of aliphatic ketones. The resulting alcohols are obtained in enantiomeric excesses ranging from 56% to 94%.