New Selective Approach To p-Chlorocalix[4]arenes Synthesis

Background: Calixarenes are well-known building blocks in supramolecular chemistry. Introduction of the halogen atom at the upper rim of the molecule allows to obtain very promising synthons for synthesis of more complex calixarene structures. Each halogen is specific for the certain types of reactions. It is known that chlorine derivatives are preferable for the Kumada, Hiyama, Stille, Negishi, Suzuki cross-coupling reaction and Buchwald-Hartwig amination. para-Сhlorinated derivatives of calix[4]arene were described in the literature even less than other halogenated ones because of their synthesis complication (low yield construction from chlorophenols). Methods: To increase the yield of p-chlorinated calix[4]arene and to reduce the number of synthetic steps ipso-chlorination reactions were tried. Reactions were carried out in dry tetrachloromethane with sulfuryl chloride in the presence of Lewis acids (AlCl3, FeCl3, PCl5). Results: It was shown that PCl5 presence led to the best yield (57%). It was almost two times higher than in the case of aluminum chloride use. Unfortunately, the reaction with FeCl3 did not give the individual product. Conclusion: A new method for synthesis of dichlorinated at the upper rim calix[4]arenes via ipsochlorination with sulfuryl chloride in the presence of phosphorous pentachloride was developed. The influence of other Lewis acids was studied. The number and position of chlorine atoms in the structure of obtained compounds were confirmed.