A Conformational Study of [3.3](2,6)Pyridinophane by the Dynamic NMR Method and X-ray Structural Analysis
作者:Katsuya Sako、Hitoshi Tatemitsu、Satoru Onaka、Hiroyuki Takemura、Satoshi Osada、Gang Wen、Teruo Shinmyozu、Jerzy M. Rudziński
DOI:10.1002/jlac.199619961023
日期:1996.10
A variable-temperature 1H-NMR study and X-ray structural analysis show that the most stable conformational isomer of [3.3](2,6)pyridinophane 2 is the syn(boat-boat) conformer, and the relative stability order of the three stable conformers is syn(boat-boat) > syn(chair-boat) > syn(chair-chair). This is in sharp contrast to the relative stability order of the parent [3.3]metacyclophane 1: syn(chair-chair)
可变温度1 H-NMR研究和X射线结构分析表明,最稳定的[3.3](2,6)吡啶吡啶2构象异构体是syn(boat-boat)构象异构体,并且其相对稳定顺序为三个稳定的符合者是syn(船-船)> syn(椅子-船)> syn(椅子-椅子)。这与母体[3.3]元环烷1的相对稳定性顺序形成鲜明对比:syn(椅子-椅子)> syn(椅子-船)> syn(船-船)。syn(船艇)适形器2c的高稳定性 主要由于氮孤对(N-1,N-2)与桥中心碳原子上的轴向氢原子(2A-H,11A-H)之间的分子内氢键引起的弱吸引力相互作用,如它们的短环形距离(2.50Å)。