不对称硼催化反应的理论研究(Ⅰ)——噁唑硼烷催化苯基乙酮还原反应的对映体选择性机理  

Theoretical Studies on Asymmetric Boron-catalyzed Reaction(Ⅰ) The Enantioselectivity in Oxazaborolidine-catalyzed Reductions of Phenyl Ethyl Ketone

作　　者：孙成科[1] 杨思娅[2] 马思渝[1] 李宗和[1] 

机构地区：[1]北京师范大学化学系,北京100875 [2]曲靖师范学院,曲靖655000

出　　处：《高等学校化学学报》2002年第1期109-112,共4页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金 (批准号 :2 97730 0 7);云南省教委科学研究基金 (批准号 :0 0 12 2 4)资助

摘　　要：用 AM1方法研究了唑硼烷催化苯基乙酮还原反应的对映体选择性机理 ,结果表明 ,在此硼催化剂的作用下 ,苯基乙酮还原的对映体产物主要是 R构型 ,其主要原因是两种对映体的催化过渡态的活化能相差较大所致 .用过渡态活化理论计算所得光学产率 e.e.=95 % 。The reaction mechanism of the enantioselectivity in oxazaborolidine catalyzed reductions of phenyl ethyl ketone has been studied by using AM1 method and transition state theory. The results show that the boron catalyzed reactions consist of two similar parallel reactions in which the reactants( R ) of the title compound and boron catalyst generate the enantiomers(P R and P S ) via intermediate compounds IC( R ) and IC( S ) and transition states TS R and TS S , respectively. The enantioselectivity is determined by the ratio of the rate constants of two reactions. The value is 40 (that is R∶S =97.5∶2.5 or e.e. (R) =95%), which is in good consistence with experiment [exp. e.e. (R) =97(95)%]. The determining factors of the rate ratio come from the joint contribution of the activation enthalpy and activation entropy.

关 键 词：苯基乙酮 对映体 选择性 AM1 还原反应 不对称催化反应 恶唑硼烷 催化剂 

分 类 号：O625.42[理学—有机化学] O621.34[理学—化学]