作者:W. Brian Jennings、Noel J. P. McCarthy、Padraig Kelly、John F. Malone
DOI:10.1039/b916021n
日期:——
NMR spectra of imines and nitrones derived from benzophenone and phenylalanine or tyrosine show clear evidence of an aromatic edge-to-face interaction in solution. At low temperatures the two ortho protons of the edge interacting phenyl ring become topically resolved with the ortho proton NMR signal involved in the CH-Ï interactions shifted well upfield (δ 5.4â5.8 at â88 °C) of the other ortho signal. Introduction of a para substituent into the phenylalanine ring has a modest effect on the upfield shift. The edge-to-face arrangement also manifests in the X-ray crystal structures of two of these compounds. Barriers to rotation around the syn phenyl-imino bond are also reported (10.5â11.1 kcal molâ1).
由二苯甲酮和苯丙氨酸或酪氨酸衍生出的亚胺和硝基的 NMR 光谱显示出溶液中芳香族边缘到面相互作用的明显证据。在低温条件下,边缘相互作用的苯环的两个正质子发生了局部分辨,参与 CH-Ï 相互作用的正质子 NMR 信号向另一个正质子信号的远上场移动(§88 °C时为´5.4â5.8)。在苯丙氨酸环中引入对位取代基对上场移动的影响不大。在其中两种化合物的 X 射线晶体结构中,也出现了从边缘到表面的排列。报告还指出了围绕合成苯基-亚氨基键旋转的障碍(10.5â11.1 kcal molâ1)。