Variable Ion Selectivity in [<i>n</i>.3.3](1,3,5)Crownophanes: The “Breathing” Process
作者:Jianwei Xu、Yee-Hing Lai、Weiling Wang
DOI:10.1021/ol034424k
日期:2003.8.1
Graphics A series of dithia[n.3.3](1.3.5)crownophanes were synthesized by cesium carbonate-assisted intramolecular cyclization reactions in 10-31% yields. Their complexation behavior exhibits an unusual ion-selectivity preference due to the presence of a "breathing" process of the dithia[3.3]metacyclophane moiety, which indirectly controls the ion selectivity through the adjustment of the cavity size of the crown unit. This breathing mechanism is also supported by observation made in X-ray crystallographic analysis.
Synthesis, X-ray crystallographic, and dynamic 1H NMR studies of crown-tetrathia[3.3.3.3]metacyclophanes—conformational control by cooperative intramolecular C–H⋯π interaction both in solid state and in solution
作者:Jian-Wei Xu、Wei-Ling Wang、Yee-Hing Lai
DOI:10.1016/j.tet.2005.07.071
日期:2005.9
Crown-tetrathia[3.3.3.3]metacyclophanes 3a–c were synthesized via intermolcular coupling reaction in 22–30% yields. X-ray crystal analysis of 3b revealed that it adopted a perpendicular conformation (3b-B or 3b-C) in which two aromatic rings were inclined to be perpendicular to the opposite aromatic rings, driving two internal methyl groups into the π-cloud of the corresponding benzene rings. Furthermore