Intramolecular Cyclizationstrategy--design, Synthesis, Characterization Of Calix[4]crown Arene

Calixarenes are one of the most popular molecular in supermolecular chemistry.calix[4]arenes are good construction platform not noly for their facile synthesis,flexible conformation but also for their predesigned molecular substitution.Since twenty years age ,the most widely investigated class of cation ligands based on calixarenes—The Calix[4]arene-crown ethers or calix[4]crowns was firstly synthesised occasionally.The marriage between calixarene and crown ether was for the purpose of utilizing possible synergic effect of the two receptor elements to realize ameliorated binding ability as well as selectivity towards specific guests. Early experiments on calix[4]crowns which designed to propose different potent other than calixarenes and crown ethers showed that the introduction of the crown ether loop at the lower rim of calix[4]arenes not only increased the cation binding ability of the parent calix[4]arene, but allowed control of the selectivity through the moderation of the crown ether size.In such a case it was highlighted by scientists since it is born. there has been no report on calixcrowns with the size of the crown ether moieties purely comprising oligoethylene glycol units larger than six.herein we report the facile synthesis of a calix[4]crown-9 cone conformer using an strategy of connecting two oligoethylene glycol units to calix[4]arene,then selective monotosylation of symmetrical diols mediated by silver oxide, subsequent intramolecular cyclization was smoothly achieved in the presence of NaH in THFIn this paper, intramolecular cyclization strategy for synthesis of a series of cone conformation macrocyclic of calix [4] -7 crown and Calix [4] crown -9 derivatives was introduced, high yielding and of a certain degree generality was found in this method. Intermediate product and the structure was confirmed by NMR (1H NMR and 13H NMR), mass spectrometry (ESI-MS) and elemental analysis. This kind of macrocyclic calix [4] crown ethers can be used as metal ion carrier or as rotaxanes, catenanes,which are the construction modules for molecular machines and has a practical potential.