CALIX[4]ARENE SULFONATES - PALLADIUM-CATALYZED INTERMOLECULAR MIGRATION OF SULFONYL GROUPS AND ISOLATION OF A CALIX[4]ARENE IN A CHIRAL 1,2-ALTERNATE CONFORMATION

An intermolecular migration of sulfonyl groups in 1,3-bistriflate and 1,3-bismesylate derivatives of p-tert-butylcalix[4]arene (1) takes place in the presence of both a palladium catalyst and chloride anion. The process leads to the clean formation of 1:1 mixtures of mono- and trisubstituted derivatives that could not be prepared directly from 1 by sulfonylation reactions. A trismesylate 7b is obtained as a minor derivative under the conditions required for the mesylation of 1. Compound 7b exists in a 1,2-alternate conformation, which is chiral due to the pattern of substituents.