Macroheterocycles. 34. Synthesis and enantiomeric selectivity of chiral azacrown
Chiral azacrown ethers were obtained by the condensation of (4S,5S)-4,5-ditosyl-oxymethyl-2,2-dimethyl-1,3-dioxolane with 6-benzyl-3,9-dioxa-6-azaundecane-1,11-diol. Their debenzylation and deacetalization were realized. The enantiomeric selectivity in the complex formation between the obtained crown ethers and the hydrochlorides of L- and D-valine methyl esters was determined by a potentiometric method. The chiral azacrown ethers exhibit higher enantioselectivity than their oxygen analogs.