Synthesis of Unsubstituted Thia Crown Ethers <i>via</i> Intramolecular Cyclization

Abstract

Abstract A remarkable temperature dependence of the template effect of alkali metal cations was found in the cyclization of thio analogs of penta- or hexaethylene glycols to thia 15-crown-5 or 18-crown-6. The optimum range of the reaction temperature was found to be 80–100 °C.