【摘要】 利用半经验PM3方法,研究了C82与甲亚胺叶立德1,3-偶极环加成反应的机理与区域选择性,计算结果表明:C82的1,3-偶极环加成反应遵循分步机理,是一个放热反应;反应活化能随着所加成键的键长增大而增加,无论是从热力学还是从动力学方面考虑,最优先加成的位置是键长最短、张力最大的键.更多还原

【Abstract】 1,3-Dipolar cycloadditions of C82 (C2v) with N-methylazomethine have been studied at the PM3 level, and their mechanism and regiochemistry were investigated. Calculational analyses of these reactions show that 1,3-dipolar cycloadditions of C82 with N-methylazomethine follow a stepwise mechanism and these reactions are exothermic. The activation barrier of the reactions is increased as the bond length of the reaction site is enlarged. Not only from energetics but also from thermodynamic point of view, the most fa- vored reaction site is the bond with the shortest length and the largest strain.更多还原