作者:Daisuke Shimoyama、Toshiaki Ikeda、Ryo Sekiya、Takeharu Haino
DOI:10.1021/acs.joc.7b02301
日期:2017.12.15
helical conformations, whereas the two resorcinarenes of 1c–e were in parallel orientations in which the clefts of the aliphatic chains entrapped one or two solvent molecules. The conformational study revealed that the helix interconversion between the (P)- and (M)-helical conformers depended on the length of the aliphatic chains. 1a had the largest energetic barrier to helix interconversion, while
以极高的收率获得了双resorcinarenenes 1a – d,最后以50%的收率获得了1e。X射线衍射分析表明1a和1b呈螺旋构象,而1c – e的两个间苯二芳烃呈平行方向,其中脂族链的裂口截留了一个或两个溶剂分子。构象研究表明(P)-和(M)-螺旋构象体之间的螺旋相互转化取决于脂族链的长度。1a在螺旋互变中具有最大的能量屏障,而在1b中,其更灵活的脂族链降低了其能量屏障。1a的P / M互变与两个间苯二芳烃的环间氢键的顺时针/逆时针互变耦合。较大的负熵贡献表明过渡态最有可能比基态更有序,这表明过渡态最有可能是对称的并且被水分子溶剂化。在M06-2 X / 6-31G(d,p)水平进行的计算表明,更稳定的(P)构型在两个间苯二碳氢芳烃之间具有顺时针的环间氢键。