The York Research Database

Calix[4]arenes immobilized in the 1,2-alternate and 1,3-alternate conformations were directly mercurated using Hg(TFA)₂. The reaction regioselectivity was compared with the thermodynamic stability of the corresponding products obtained by theoretical calculations (wB97XD/def2tzvp method). Both experimental and theoretical data suggest that para substitution is slightly preferred over meta attack for the 1,2-alternate conformer, while in the case of the 1,3-alternate conformation the situation is reversed. The usefulness of the mercury intermediates was demonstrated by the synthesis of a rigid upper-rim-bridged calixarene in the 1,2-alternate conformation possessing a highly distorted cavity. A simple transformation of the organomercury compounds afforded the corresponding iodo derivatives, which are potentially applicable as building blocks for further synthesis. Moreover, many products are inherently chiral representing unique substitution patterns inaccessible by common “mercury-free” chemistry.