Functionalization of Calix[4]resorcinolarenes with Trimethylsilyl Isocyanate

Abstract

Calix[4]resorcinolarenes and their dialkylaminomethylated derivatives react with trimethylsilyl isocyanate to form addition products containing four silylcarbamate groups. These compounds are unstable and, depending on the nature of alkyl groups at the lower rim of the macrocycle, undergo two types of transformations. Intramolecular silylation yields calixarenes containing four carbamate and four trimethylsilyloxy groups at the upper rim. In the case of dialkylaminomethylated calixarenes, the initially formed addition products can undergo intramolecular cyclization to form a cavitand with four six-membered fragments at the upper rim.