Selective Lower Rim Reactions of 5,17-Upper Rim-Disubstituted Calix[4]arenes

摘要

p-tert-Butylcalix[4]arene, easily accessible via base-induced condensation of p-tert-butylphenol and formaldehyde, provides a convenient starting material for the preparation of calixarenes carrying a wide variety of groups on the upper and lower rims. The selective introduction of these groups, however, continues to be a challenge to the synthetic chemist, and several approaches to this problem have appeared in the literature. The work described in this paper employs one that involves the preparation of calix[4]arenes disubstituted on the upper rim followed by selective substitution on the lower rim to yield calix[4]arenes that can be captured in one of three conformations.