The synthesis of tetracarbonyl derivatives of thiacalix[4]arene in different conformations and their complexation properties towards alkali metal ions

The three conformations of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis[(benzoyl)methoxy]-2,8,14,20-tetrathiacalix[4]arene 1: cone, partial cone and 1,3-alternate, were prepared by the treatment of 5,11,17,23-tetra-tert-butyl-2,8,14,20-tetrathiacalix[4]arene-25,26,27,28-tetraol (TCA) with alpha-bromo acetophenone in the presence of appropriate alkali carbonate M2CO3 (M=Na, K, Cs) as base catalyst in acetonitrile. Structure of the conformers were established by H-1 NMR, H-1-H-1 COSY, ID NOE, 2D ROESY and X-ray experiments. The alkali cation binding selectivity of the obtained macrocycles was investigated by the ion-pair extraction method. (C) 2003 Elsevier Science Ltd. All rights reserved.