Aza crown ethers.13C and1H NMR studies of ring conformations and stereochemically dependent shifts inN-substituted dibenzodiaza-18-crown-6 ethers and a nine-membered analog
作者:G. W. Buchanan、D. J. Landry
DOI:10.1002/mrc.1260290206
日期:1991.2
analogous dibenzodiaza‐18‐crown‐6 ethers and their 9‐membered ring counterparts. On the basis of geometries deduced from 1H1H NOESY results, the upfield 13C chemical shifts in the 18‐membered systems are attributed to cis coplanar interactions between the terminal carbons of these torsional networks. Overall mobilities of 9‐ and 18‐membered ring systems are examined via 13C spin–lattice relaxation times
在溶液中和固相中,在结构类似的二苯并二氮杂-18-冠-6 醚与其 9 元环对应物的邻位芳族碳之间观察到显着大 (> 10 ppm) 13C NMR 化学位移差异。根据从 1H1H NOESY 结果推导出的几何形状,18 元系统中的高场 13C 化学位移归因于这些扭转网络的末端碳之间的顺式共面相互作用。通过 13C 自旋-晶格弛豫时间检查 9 元和 18 元环系统的整体迁移率。