On the Conformation of 8-Membered Ring Heterocycles – Dynamic and Static Conformational Analysis of Acylated Hexahydrobenzazocines
作者:Alfred Hassner、Boaz Amit、Vered Marks、Hugo E. Gottlieb
DOI:10.1002/ejoc.200500591
日期:2006.3
is forced out of conjugation with the nitrogen in the transition state. A detailed analysis of vicinal proton-proton coupling constants, supported by molecular mechanics calculations, indicates that these compounds exist at room temperature as a mixture of fast-interconverting conformers of the octacycle. This is proved by the observation of two species in the 13C NMR spectrum of the parent compound
几种酰化六氢苯并佐辛的高场 NMR 分析表明,令人惊讶的是,环亚甲基在室温下通常是非对映异构的,因为八元环对映异构化过程的障碍比预期的要高得多。结果表明,环反转与酰胺部分的旋转相关(但不协调),因为羰基被迫与过渡态的氮共轭。分子力学计算支持的邻位质子-质子偶联常数的详细分析表明,这些化合物在室温下作为八环快速互变构象异构体的混合物存在。在低于– 90 °C 的温度下,在母体化合物的13C NMR 光谱中观察到两种物质证明了这一点。