condensation. Standard derivatization procedures always led to the formation of mixtures of various conformational isomers from which the derivative in the cone-conformation could be isolated only by preparative HPLC. For a tetraester derivative it was shown by two-dimensional 1H NMR spectroscopy, that due to the different substituents the cone-conformation is strongly distorted. The sodium complex of this tetraester
通过片段缩合已经制备了几种在对位具有三个或四个不同取代基的手性杯[4]
芳烃。标准的衍生化程序总是导致形成各种构象异构体的混合物,仅通过制备型HPLC可以从中分离出圆锥构象的衍
生物。对于四酯衍
生物,通过二维1 H NMR光谱显示,由于取代基的不同,其圆锥构象强烈扭曲。然而,该四酯的
钠络合物再次呈现规则的锥构型。