Influence of intramolecular hydrogen bonding on the conformational equilibrium of<i>cis</i>-3-<i>N</i>,<i>N</i>-dimethylaminocyclohexanol compared with<i>trans</i>-3-<i>N</i>,<i>N</i>-dimethylaminocyclohexanol and<i>cis</i>- and<i>trans</i>-3-<i>N</i>,<i>N</i>-dimethylamino-1-methoxycyclohexane
作者:P. R. de Oliveira、D. S. Ribeiro、R. Rittner
DOI:10.1002/poc.896
日期:2005.6
1H NMR data show that concentration increase shifts the conformational equilibrium of cis-3-N,N-dimethylaminocyclohexanol (1) (cis-3-DACH) from the 1aa conformer, stabilized by an intramolecular hydrogen bond (IAHB), to the 1ee conformer [43% (0.01 M) to 70% (0.40 m), in CCl4], which can form intermolecular hydrogen bonds (IEHB). The percentage of 1ee conformer also increases with the solvent basicity
1 H NMR数据表明,浓度增加将顺式-3- N,N-二甲基氨基环己醇(1)(顺式-3-DACH)的构象平衡从1aa构象异构体(通过分子内氢键(IAHB)稳定)转移到1ee上构象异构体[在CCl 4中为43%(0.01 M)至70%(0.40 m)],可以形成分子间氢键(IEHB)。1ee构象剂的百分比也随着溶剂碱度的增加而从C 6 D 12中的36%增加到DMSO中的89%。反式构象平衡异构体(反式-3-DACH)也取决于浓度,因为1ae在CCl 4中从77%(0.05 M)增加到84%(0.40 M),但不具有溶剂极性。IAHB在顺-3-DACH中的存在已通过对模型化合物顺式-3- N,N-二甲基氨基-1-甲氧基环己烷(2)(顺式-3-DAMCH)缺乏OH基和呈现一个单一的构象异构体2ee(〜95%)。相应的反式异构体(反式-3-DAMCH)的行为与反式相似-3-DACH,因为