Synthesis of azacrown ethers modified with side-chains containing germanium

The reaction between ethanolamine (4) and tri- or tetraethylene tosylate (5) and (13) gave 9- and 12-membered monoazacrowns with a CH2CH2OH residue on nitrogen, A-OH and B-OH, together with 18- and 24-membered diazacrown ethers with the same substituent on nitrogen, E-OH and F-OH. If 2-(2-aminoethoxy)ethanol (12) was used in the reaction described above, instead of 4, the final products, G-OH and H-OH, and K-OH and L-OH, have a longer side chain, CH2CH2OCH2CH2OH, on nitrogen (Route 1). A series of reactions involving bromoethanol (6) and diethanolamine (9) formed, with 5 or 13, 18- and 24-membered monoazacrowns with the shorter substituent as described above, a 15-membered monoazacrown ether C-OH and an 18-membered D-OH. If 2-(2-chloroethoxy)ethanol (14) is used instead of 6, I-OH and J-OH are obtained (Route 2′). All these hydroxy azacrown ethers were made to react with 3-trimethylgermylpropionic acid (18) to give the corresponding germanium-containing A–L. A preliminary investigation was carried out on the cation transport capability of these germanium-containing azacrown ethers to observe whether germanium might enhance their cation transporting capability.