The synthesis of a series of macrocyclic polyethers (crown ethers) of interest as carriers for the countertransport of metal ions and protons across artificial membranes is described. Thallium mediated cyclization of oligoethyleneglycol diiodides with (+)-N, N,-N', N'- tetramethyltartaramide gave 15-crown-5 and 18-crown-6 diamides which were converted, via the diacids and anhydrides, to crown ether monoamides bearing long chain alkyl ...
[Beall, L. Scott; Mani, Neelakandha S.; White, Andrew J. P.; Williams, David J.; Barrett, Anthony G. M.; Hoffman, Brian M. Journal of Organic Chemistry, 1998 , vol. 63, # 17 p. 5806 - 5817]