Catalytic asymmetric borane reduction of prochiral ketones by the use of diazaborolidine catalysts prepared from chiral β-diamines

The catalytic asymmetric borane reduction of prochiral ketones was examined in the presence of chiral diazaborolidine catalysts prepared in situ from chiral P-diamines and borane. Chiral secondary alcohols were obtained with modest to high enantiomeric excesses (up to 92% ee) using (S)-2-[(4-trifluoromethyl)anilinomethyl]indoline 2f. (C) 2000 Elsevier Science Ltd. All rights reserved.