摘要
N-烯基硝酮分子内环加成反应具有区域选择性,如图1.当n=2,R^1=R^2=R^3=H时,即N-4-戊烯基硝酮分子内环加成反应.实验表明,P_a的产率为23%,P_b为47%.我们曾用MINDO/3方法对此反应进行IRC计算,确证P_a、P_b是经由反应物两种不同构象(R_a、R_b)分别得到的产物,并讨论了二反应活化势垒的差别对区域选择性的影响.Tufariello等人认为,P_b的较高产率主要由于2个产物的过渡态的熵差别.为此,本文从理论上考察活化熵和活化焓对区域选择性的影响.
The reaction mechanism of the intramolecular cycloaddition of N-4-pentenyl nitrone was investigated theoretically by using AM1 MO method and transition state theory. There are two parallel reactions leading to two different regioisomers. The geometries of the reactants, TS and products were optimized. The ratio of the rate constant of the two reactions is 1. 2 (at 383. 75 K) and is in good consistence with experiments.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
1992年第6期837-839,共3页
Chemical Journal of Chinese Universities
基金
国家教育委员会博士点基金
关键词
戊烯基硝酮
分子内环加成
Regioselectivity, N-4-pentenyl nitrone, Intramolecular cycloaddition