Syntheses of lower-rim-1,3-crowned calix[6]arenes and their complexation abilities toward cations

An approach to lower-rim-1,3-crowned calix[6]arene and its derivatives in o ne-pot process has been accomplished. In the presence of very excess Na2CO3 (27-150 equivalent per mole p-tert-butylcalix[6]arene 1) in acetonitrile, the lower-rim-1,3-bridged calix[6]crown-3 (4), the bistosylethoxy-ethyl der ivative of 4 (5), as well as the intermediate of 4, monotosylethoxyethyl p- tert-butylcalix[6]arene 3, were obtained in rational yields, the distributi on of the three compounds varied with the amount of the base used and other selected experimental conditions. 4 exhibits high selectivity towards Li+. 3 may be the first example of ionophore with high Et2NH2+ selectivity.