Chiral synthesis via organoboranes. 41. The utility of B ‐chlorodiisopinocampheylborane for a general synthesis of enantiomerically pure drugs

A general approach to the synthesis of enantiomerically pure α‐phenyl amino alcohols via the asymmetric reduction of α‐phenyl haloalkyl ketones or α‐phenyl aminoalkyl ketones with B ‐chlorodiisopinocampheylborane is described. Using this approach, an improved synthesis of a potential antipsychotic, α‐(4‐fluorophenyl)‐4‐(2‐pyrimidinyl)‐1‐piperazinebutanol in ⩾98% ee, and the broncholdilator 1‐(2‐methoxy‐2‐phenethyl)‐4‐(3‐hydroxy‐3‐phenylpropyl)piperazine (eprozinol) in ⩾99% ee is achieved. © 1995 Wiley‐Liss, Inc.