由(1R,2S)-麻黄碱制备的硼杂噁唑烷催化甲硼烷不对称还原苯乙酮

Asymmetric Reduction of Acetophenone with Borane Catalyzed by Chiral Oxazaborolidine Prepared from (1R, 2S)-Epherdrine

由(1R,2S)-麻黄碱制得了五个新的手性硼杂(口恶)唑烷1～5,它们催化甲硼烷不对称还原苯乙酮,获得了高产率的具有38.5～72.4％e.e.的R-1-苯基乙醇。讨论了催化剂的结构-活性关系及反应参数(催化剂用量、反应温度)对还原反应对映选择性的影响。

Some new oxazaborolidines 1- 5, Prepared from the reaction of (\R, 25) -epherdrine and BH3 ·SMe2 or RB(OH)2, Serve as chiral catalysts for the asymmetric reduction of acetophenone with borane to give the (R)-1-phenylethanol with 38.5-72.4% e.e. in high yield. The structure-reaction relationship of the catalysts and the effect of reaction parameters (the amount of catalyst and reaction temperature) on enantioselectivity of the reduction are discussed.