CAJ | 학술논문

用密度泛函B3LYP方法研究了过渡金属钐类卡宾与乙烯的环丙烷化反应的机理.对三种不同的钐的SS试剂CH3SmCH2X(其中X=Cl、Br和I)分别和CH2CH2反应的各反应物、中间体、过渡态和产物构型的全部结构几何参数进行了优化,用内禀反应坐标(IRC)计算和频率分析方法,对过渡态进行了验证.结果表明:CH3SmCH2X(其中X=Cl、Br和I)与CH2CH2环丙烷化反应按亚甲基转移通道(通道A)和卡宾金属化通道(通道B)都可以进行,与锂类卡宾的反应机理相同,只是按亚甲基转移通道(通道A)进行反应较容易一些,而且此反应在较低的温度下就可以发生.
용밀도범함B3LYP방법연구료과도금속삼류잡빈여을희적배병완화반응적궤리.대삼충불동적삼적SS시제CH3SmCH2X(기중X=Cl、Br화I)분별화CH2CH2반응적각반응물、중간체、과도태화산물구형적전부결구궤하삼수진행료우화,용내품반응좌표(IRC)계산화빈솔분석방법,대과도태진행료험증.결과표명:CH3SmCH2X(기중X=Cl、Br화I)여CH2CH2배병완화반응안아갑기전이통도(통도A)화잡빈금속화통도(통도B)도가이진행,여리류잡빈적반응궤리상동,지시안아갑기전이통도(통도A)진행반응교용역일사,이차차반응재교저적온도하취가이발생.
In order to have efficient and highly stereoselective cyclopropanating reagents, the cyclopropanation reaction of ethylene promoted with Samarium(Ⅱ) carbenoid [Simmons-Smith(SS)reagent] were studied by means of B3LYP hybrid density functional method. The geometries for reactants, transition states and products are completely optimized. All transition states were verified by the vibrational analysis and the intrinsic reaction coordinate (IRC) calculations. The results showed that, identical with the lithium carbenoid,CH3SmCH2X(X=Cl, Br and I) can fairly react with ethylene via both methylene transfer pathway (pathway A) and carbometalation pathway (pathway B). And the cyclopropanation reaction via methylene transfer pathway proceeds with a lower barrier and at lower temperatures.