Conformational studies of N-carbomethoxy-2-alkoxyindolenines by dynamic NMR, crystallography, and molecular mechanics
作者:Oscar R. Suárez-Castillo、Yaneth M.A. Contreras-Martínez、Lidia Beiza-Granados、Myriam Meléndez-Rodríguez、J. Roberto Villagómez-Ibarra、J. Martín Torres-Valencia、Martha S. Morales-Ríos、Pedro Joseph-Nathan
DOI:10.1016/j.tet.2005.07.023
日期:2005.9
and the transformation to their tautomeric indoles is reported. Variable-temperature 1H NMR studies of these 2-alkoxyindolenines evidenced dynamic processes involving two low-energy E and Z equilibrating conformers around the N–C(O) carbamate bond, for which the barriers (ΔG≠) between the two conformations are in the order of 12.5–13.9 kcal/mol, as deduced from computational NMR line shape simulations
报道了N-羰甲氧基-2-烷氧基吲哚烯的合成和向其互变异构吲哚的转化。这些2-烷氧基吲哚胺的可变温度1 H NMR研究表明,动态过程涉及围绕N–C(O)氨基甲酸酯键的两个低能E和Z平衡构象异构体,这两个构象之间的壁垒(ΔG ≠)为从NMR线形模拟计算得出,其数量级为12.5-13.9 kcal / mol。旋转势垒随着烷氧基基团的体积的增加而降低,其中E构象异构体总是更稳定。分子力学计算证明是首选准分子与X射线衍射研究一致,随着空间效应的增加,五元环中烷氧基的N轴位置。