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 contain one or more pyridyl units are reported. The results of alkali metal picrate extraction experiments performed by using 11 and 12 are compared with those 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 considerably lower avidity than its corresponding model system, 3, toward extraction of alkali metal picrates from aqueous solution into CHCl3. In addition, a highly 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 rights reserved.