Missing-link macrocycles: hybrid heterocalixarene analogues formed from several different building blocks.
Missing-link macrocycles: hybrid heterocalixarene analogues formed from several different building blocks.
复制标题
缺失环节大环化合物：由几种不同的结构单元形成的混合杂杯芳烃类似物。
作者：
J. Sessler;Won;V. Lynch;V. Král
介绍了含吡咯、苯、甲氧基取代苯和吡啶亚基的杂化[4]芳烃类似物的合成和结构表征。大环1和大环2分别是杯[2]苯[2]吡咯和杯[1]苯[3]吡咯体系的例子，它们是由吡咯和适当的苯基双甲醇缩合而成的。以杯[2]苯[1]吡啶[1]吡咯和杯[1]吡啶[3]吡咯为例，采用羰基吡咯扩环法合成了杯[2]苯[1]吡啶[3]吡咯。单晶x射线分析表明，化合物1a、1b和2b在固体状态下采用1,3-交替构象，而化合物3和7的构象最好描述为“扁平部分锥体”。（系列a指纯苯衍生体系，而系列b指含有5-甲氧基苯基亚基的大环）。在固体状态下，甲氧基功能化的大环1b和2b以及含氯吡啶的大环7以二聚体形式存在。在1a和7的情况下，这些化合物在固体状态下与中性溶剂相互作用。通过温度相关质子核磁共振和NOESY光谱分析探讨了溶液中大环的构象。在188 K时，大环1a和2a采用扁平的1,3-交替构象，而大环3和7以扁平的部分锥形构象存在。在大环1a和2a的情况下进行了标准质子核磁共振滴定分析，结果表明，至少第二个系统能够在室温下在CD(2)Cl(2)溶液中结合氟和氯阴离子(在2a和F（-）和Cl（-）的情况下，K（a)分别为571和17M(-1)）。
The synthesis and structural characterization of hybrid heterocalix[4]arene analogues containing pyrrole, benzene, methoxy-substituted benzene, and pyridine subunits is described. Macrocycles 1 and 2, examples of calix[2]benzene[2]pyrrole and calix[1]benzene[3]pyrrole systems, respectively, are synthesized by the condensation of pyrrole and an appropriate phenylbis(carbinol). Macrocycles 3 and 7, examples of calix[2]benzene[1]pyridine[1]pyrrole and calix[1]pyridine[3]pyrrole, respectively, are synthesized by the use of a carbene-based pyrrole-to-pyridine ring-expansion procedure. Single-crystal X-ray analysis reveals that compounds 1a, 1b, and 2b adopt 1,3-alternate conformations in the solid state, whereas compounds 3 and 7 display structures that are best described as "flattened partial cones" in terms of their conformation. (Series a refers to pure benzene-derived systems, whereas series b indicates macrocycles containing 5-methoxyphenyl subunits). In the solid state, the methoxy-functionalized macrocycles 1b and 2b, and the chloropyridine-containing macrocycle 7 exist as dimers. In the case of 1a and 7, these compounds interact with neutral solvent in the solid state. The conformations of the macrocycles in solution were explored by temperature-dependent proton NMR and NOESY spectral analysis. At 188 K, macrocycles 1a and 2a adopt flattened 1,3-alternate conformations, whereas macrocycles 3 and 7 exist in the form of flattened partial-cone conformations. Standard proton NMR titration analyses were carried out in the case of macrocycles 1a and 2a, and reveal that at least the second of these systems is capable of binding fluoride and chloride anions in CD(2)Cl(2) solution at room temperature (K(a)=571 and 17M(-1) in the case of 2a and F(-) and Cl(-), respectively).