Synthesis of fully O-alkylated calix4arenes in a cone conformation using a liquid-liquid phase transfer catalytic process

摘要

Calix[4]arenes are cyclic tetramers made up of phenol and formaldehyde. Etherification, like esterification, can generally be effected on all of the OH groups of a calixarene regardless of ring size if sufficiently reactive reagents are used. We now report the etherification of p-tert-butyl calix[4]arene and calix[4]arene with 6-chloro-1-hexanol in Wiliamson-type reactions using a facile phase transfer catalytic method. These syntheses involve two steps. First step consists in preparation of diametrically di-substituted calix[4]arenes (DMF, at 70℃ in the presence of K_2CO_3). Finally, we have tried the exhaustive alkylation in a PTC system. The alkylation was carried out in toluene solvent at 90-100℃ with excess of aqneous NaOH (50% w w), alkylating agent and PT catalyst: telramethyl ammonium hromide, tetraethyl ammonium bromide. decyltrimethyl ammonium bromide and TEBAC (Oct_3MeN~+Cl~-). All the ethers were purified and characterized by IR,UV-VIS methods and elementary analysis. It is interesting to note that all the compounds prepared adopt a con conformation, due to strong hydrogen-bonding among the OH groups.