Enantioselective borane reduction of acetophenone catalysed by oxazaborolidines derived from chiral diethanolamines
作者:Laurent Dubois、Jean-Claude Fiaud、Henri B. Kagan
DOI:10.1016/0957-4166(95)00134-b
日期:1995.5
The synthesis of oxazaborolidines of types 1 and 2, derived from chiral diethanolamines and their behaviour, as catalysts for the asymmetric reduction of acetophenone by borane has been investigated. Bicyclic oxazaborolidines of type 2 afforded the expected alcohol in good yield but with modest ee's (ee<40%). Monocyclic oxazaborolidines of type 1 gave better results. For instance, catalyst 16 allowed
已经研究了由手性二乙醇胺衍生的1型和2型恶唑硼烷及其行为的合成,这些催化剂可作为硼烷不对称还原苯乙酮的催化剂。2型双环恶唑硼烷提供了预期的醇,收率良好,但ee适中(ee <40%)。类型1的单环恶唑硼烷给出了更好的结果。例如,催化剂16允许分离具有72%ee的(S)α-甲基苄醇,而结构上接近16的恶唑硼烷26产生了显着的对面选择性的逆转。在过渡态模型的基础上讨论了这些催化剂的对映选择性的起源。