Calix Crowns Derived from <i>para</i>-Bridged Calix[4]arenes

Two calix[4]arenes, bridged by aliphatic chains of five and eight carbon atoms spanning two opposite para positions, have been converted into their 1,3-crown ether derivatives by reaction with tetraethylene and pentaethylene glycol ditosylates. Of the two possible 1,3-crown derivatives, only the formation of those isomers is observed in which the phenolic units connected at the para positions are etherified. This has been established in one case by a single-crystal X-ray analysis. Preliminary results for the extraction of selected alkali and alkaline-earth metals are reported.