Proton-Ionizable Compounds. 19. The Synthesis of Chiral Dialkyl-SubstitutedTriazolo-18-Crown-6 Macrocycles

摘要

Four new chiral macrocyclic polyether ligands containing the proton-ionizabletriazole subcyclic unit have been prepared. The triazolo-crowns contain two isopropyl, two isobutyl, two(S)-sec butyl or two benzyl substituents on chiral macro ring carbon atoms. Proton-ionizable crown ethers have been the subject of many studies. The crown ethers containing proton-ion-izable groups are of interest because in the anion form they can neutralize positive cationic charge in metal complexation reactions. Often, cation-crown complex stability is increased when the crown is ionized. Transport of cations through liquid membrane systems by proton-ionizable ligands is pH dependent so that transport can be turned on and off by adjusting the pH(3-5). Other uses for the proton-ionizable crowns are given in a recent review. (js)