The reaction of N'-thiobenzoyl -N, N-dimethylformamidine (I) with electron-dificient dienophiles was investigated.The reaction of I with N-substituted maleimides (II) afforded exo and endo 1 : 1 cycloadducts (III). The stereochemistry was determined by analysis of 1H-nuclear magnetic resonance (1H-NMR) spectral data based on the modified neglect of diatomic overlap (MNDO) optimized structures. An equilibrium was observed between the starting materials (I and II) and 1 : 1 cycloadducts (III). The reaction of I with II in the presence of acetic acid afforded thiazine derivatives(IV), through elimination of dimethylamine from the primary cycloadduct (III). The reactions of I with several electron-deficient dienophiles were also examined. The reaction behavior is discussed in terms of frontier molecular orbital (FMO) theory and kinetic factors.
研究了 N'-
硫代苯甲酰基-N, N-二甲基
甲脒(I)与电子异构体二烯烃的反应。根据改进的忽略二原子重叠(MNDO)优化结构,通过分析 1H 核磁共振(1H-NMR)光谱数据确定了立体
化学结构。在起始材料(I 和 II)和 1 : 1 环加成物(III)之间观察到了平衡。I 与 II 在
乙酸存在下反应,通过消除初级环加合物(III)中的
二甲胺,得到了
噻嗪衍
生物(IV)。此外,还研究了 I 与几种缺电子的亲电子体的反应。根据前沿分子轨道(FMO)理论和动力学因素对反应行为进行了讨论。