Selective acyl and alkylation of monobenzoyl p-tert-butylcalix[4]arene

Several calixarene derivatives of 5,11,17,23-tetra-tert-butyl-25-(3,5-dinitrobenzoyloxy)-26,27,28- trihydroxycalix[4]arene 2 were synthesized by the reaction of 2 with several acyl and alkylating agents in the presence of base such as pyridine and K2CO3 in THF. Acylation of monobenzoylated p-tert-butylcalix[4]arene 2 yielded their corresponding 1,3-diacylated calix[4]arenes 3a-3g. On the other hand, alkylation of 2 produced a variety calix[4]arene derivatives such as 1,2- and 1,3-disubstituted calix[4]arenes 4a-4c, 4e-4f, or 1,2,4-trisubstituted calix[4]arene 4d. 1,2-Disubstituted calix[4]arenes are chiral. All derivatives exist as a cone conformation based on NMR studies.