4-甲基-5-烯-庚腈氧化物分子内环加成反应的立体选择性  

THEORETICAL STUDY ON THE STEREOSELECTIVITY OF INTRAMOLECULAR 4-METHYL-5-ETHENYL-HEPTANITRILE OXIDE CYCLOADDITION

作　　者：孙成科[1,2] 马思渝[1] 李宗和[1] 

机构地区：[1]北京师范大学化学系 [2]曲靖师范高等专科学校,云南曲靖655000

出　　处：《北京师范大学学报（自然科学版）》2000年第3期368-373,共6页Journal of Beijing Normal University(Natural Science)

基　　金：国家自然科学基金资助项目!(2 97730 0 7)

摘　　要：用过渡状态理论和量子化学AM1方法 ,对 4 甲基 5 烯 庚腈氧化物环加成反应机理进行了研究 .结果表明 ,虽然存在得到 2种产物的平行反应 ,但由于 2个反应的速率常数比很大 ,基本上只得到单一的反式产物 .4 甲基 5 烯 庚腈氧化物立体专一选择性不仅由活化焓决定 ,还与活化熵有关 .The reaction mechanism of 4-methyl-5-ethenyl-heptanitril e oxide cycloaddition is studied with the molecular orbital AM1 method and transit ion state theory. The result shows that the cycloaddition consists of two simila r parallel reactions in which the conformers(R a and R b) of the title compoun d generate the stereoisomers (P a and P b) via transition states TS a and TS b respectively. The stereoselectivity is determined by the ratio of the rate c onstants of two reactions. The value is 917(Y a∶Y b=99.9∶0.1), that is in good consistence with experiment (Y a∶Y b=99∶1). The determini ng factors of the rate ratio come from the joint contribution of the activation enthalpy and activation entropy.

关 键 词：4-甲基-5-烯-庚腈氧化物 环加成反应 立体选择性 

分 类 号：O623.76[理学—有机化学]