Intramolecular cyclization strategy: synthesis of 1,3- and 1,2-calix[4]crown-7 and calix[4]crown-9 cone conformers

1,3- and 1,2-calix[4]crown-7 and calix[4]crown-9 cone conformers were synthesized in acceptable yields by sequential introduction of two distal or proximal polyethylene glycolic chains with terminal hydroxyls at the lower rim, monotosylation, and intramolecular ring closure reaction. According to the two-phase extraction experiment, the title compounds showed mediocre affinity for alkali and alkaline earth metal picrates. The 1,2-calix[4]crown-9 extracted Sr2+ selectively among other alkaline earth metal cations.