BORANES IN SYNTHESIS .2. ASYMMETRIC-SYNTHESIS OF BETA-AMINO ALCOHOLS - A FACILE CONVERSION OF ALPHA-AMINO ACETOPHENONES TO THE CORRESPONDING BETA-AMINO ALCOHOLS IN HIGH ENANTIOMERIC PURITY

The asymmetric reduction of 2-amino acetophenones with Ipc(2)BH or Ipc(2)BCl at -78 degrees C, yields the corresponding beta-amino alcohols in good to excellent yields. Although only modest (12-45% ee) enantiomeric excesses were obtained with Ipc(2)BH, 75-99% enantiomeric excesses were obtained when Ipc(2)BCl was used as the asymmetric reducing agent.