TETRAHEDRON LETTERS, cilt.40, sa.11, ss.2113-2116, 1999 (SCI-Expanded)
The role of alkaline metal cations in the synthesis and in determining the conformer distribution of tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene obtained by treatment of tetrathiacalix[4]arene 1 in acetone by ethyl bromoacetate in the presence of M2CO3 was systematically investigated. Among the four possible conformers, the cone, partial cone and 1,3-alternate conformers were obtained, purified and structurally characterised by X-ray analysis in the solid state. Although for Li+ no tetra substituted derivative was observed, for Na+ the cone conformer was exclusively formed while for both K+ and Cs+ a mixture of partial cone and 1,3-alternate conformers was obtained. (C) 1999 Elsevier Science Ltd. All rights reserved.