A new method for the preparation of oxazaborolidine catalyst in situ using 1,2-aminoalcohol, sodium borohydride, and diiodomethane for the asymmetric reduction of prochiral ketones and N-substituted imines

Abstract

An oxazaborolidine catalyst is readily prepared in situ at room temperature in THF using 1,2-aminoalcohols and borane generated from sodium borohydride/CH 2I 2 reagent system. The oxazaborolidine/BH 3 reagent system prepared in this way is useful for the reduction of prochiral ketones and N-substituted imines to the corresponding alcohols and amines with moderate to good enantiomeric excesses. © Kettouche and Djerourou.