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