所述元-bridged杯芳烃具有一个僵化和高度扭曲的腔,其中,所述附加单键桥强加在整个系统上的极端内部应变。结果,与受内部应变释放支配的普通杯[4]芳烃衍生物相比,这些化合物的反应性得到了合理的修正。这可以通过桥联杯[4]芳烃与P 2 O 5的反应来证明。或Nafion-H,导致(除聚合物外)形成具有重排基本骨架的大环产物。在芴部分旁边的亚甲基桥在分子内从酚亚基的位置2移动到位置4,以使张力最小化。正如单晶X射线分析和残留偶极耦合方法的应用所揭示的那样,重排发生在不改变原始构象的情况下。
Unusual reactivity of upper-rim bridged calix[4]arenes – Friedel–Crafts alkylation via cleavage of the macrocyclic skeleton
作者:Petr Slavík、Pavel Lhoták
DOI:10.1016/j.tetlet.2018.03.072
日期:2018.5
common calix[4]arenes. As a consequence of highly enhanced inner strain, the bridged compounds can be cleaved under acidic conditions to form open oligomeric species (benzylic type carbocation) that can be used for the Friedel–Crafts alkylation of aromatic compounds. This behavior, never observed in common calix[4]arenes, demonstrates a reasonably amended reactivity invoked by the additional bridge.
Unexpected cleavage of upper rim-bridged calix[4]arenes leading to linear oligophenolic derivatives
作者:P. Slavík、H. Dvořáková、M. Krupička、P. Lhoták
DOI:10.1039/c7ob03101g
日期:——
meta-mercuration followed by Pd-catalysed intramolecular bridging gave birth to a novel type of calixarene bearing a single bond bridge between the meta positions of the neighboring aromatic subunits. These bridged derivatives possess extremely distorted cavities that imply possible amended properties over common calix[4]arenes. This new type of calixarene reactivity can be documented by acid-/electrophile-mediated
The regioselective mercuration of tetraalkylated calix[4]arenes with Hg(OCOCF3)2 leads to the formation of meta-substituted products which enabled Pd-catalysed intramolecular bridging within the calixarene skeleton. Bridged derivatives represent a completely novel substitution pattern in calixarene chemistry with extremely distorted cavities and possible applications in supramolecular chemistry.
compared with common calix[4]arene derivatives, which is governed by the release of internal strain. This can be documented by the reaction of the bridged calix[4]arene with P2O5 or Nafion-H, leading (apart from polymers) to a macrocyclic product with a rearranged basic skeleton. The methylene bridge next to the fluorene moiety is intramolecularly shifted from position 2 to position 4 of the phenolic subunit
所述元-bridged杯芳烃具有一个僵化和高度扭曲的腔,其中,所述附加单键桥强加在整个系统上的极端内部应变。结果,与受内部应变释放支配的普通杯[4]芳烃衍生物相比,这些化合物的反应性得到了合理的修正。这可以通过桥联杯[4]芳烃与P 2 O 5的反应来证明。或Nafion-H,导致(除聚合物外)形成具有重排基本骨架的大环产物。在芴部分旁边的亚甲基桥在分子内从酚亚基的位置2移动到位置4,以使张力最小化。正如单晶X射线分析和残留偶极耦合方法的应用所揭示的那样,重排发生在不改变原始构象的情况下。