Synthesis and alkali metal picrate extraction capabilities of novel, cage-functionalized, pyridine containing crown ethers and cryptands

The syntheses of novel cage-functionalized crown ethers, 11-13, that contai n one or more pyridyl units are reported. The results of alkali metal picra te extraction experiments performed by using 11 and 12 are compared with th ose obtained by using the corresponding model (non-cage) crown ethers. Cage -functionalized crown ether 11 displays greater avidity toward Li+ picrate vis-a-vis the corresponding model system, 2, whereas 12 displays considerab ly lower avidity than its corresponding model system, 3, toward extraction of alkali metal picrates from aqueous solution into CHCl3. In addition, a h ighly preorganized, cage-annulated cryptand, 16, was prepared; this unusual host molecule was found to be both highly avid and highly selective toward extraction of Li+ and Na+ picrates. (C) 1999 Elsevier Science Ltd. All rig hts reserved.