Synthesis and Structure of the Potassium Salt with Monodeprotonated 1,2,3-Tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene

Abstract

Alkylation of p-t-butylcalix[6]arene with ethyl 4-bromobutanoate in the presence of K2CO3 results in a potassium salt of the monodeprotonated 1,2,3-tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene in high yield. X-Ray crystallographic analysis shows that this compound exists as a double partial cone conformation. The potassium ion is positioned near the centre of the cavity of the macrocycle and binds to four phenolic oxygens. Close contacts between the potassium ion and phenyl rings observed in this compound are indicative of the presence of the cation–π interaction. The molecules are connected via intermolecular K+···O interactions into infinite chains.