Synthesis and structure of lower rim-substituted alkynyl derivatives of thiacalix[4]arene

Abstract

Lower-rim substituted bis- and tetrakis(alkynyloxy)thiacalix[4]arenes in cone and 1,3-alternate configurations were synthesized by the Mitsunobu reaction, and their structure was determined using homoand heteronuclear one- and two-dimensional NMR techniques. Bis(prop-2-yn-1-yloxy)thiacalix[4]arene was found to exist in conformational equilibrium whose position depends on the temperature and reaction conditions.