Synthesis of novel C2-symmetric chiral crown ethers and investigation of their enantiomeric recognition properties

Abstract

A series of new C 2-symmetric chiral aza crown ether macrocycles 1– 4 have been synthesized from ( S)-3-aryloxy-1,2-propanediol and ( S)-1,2-propanediol for the enantiomeric recognition of amino acid ester derivatives. These new macrocycles have been shown to be strong complexing agents for primary organic ammonium salts (with K up to 176.93 M −1 and Δ G° up to 12.81 kJ mol −1) by 1H NMR titration. These macrocyclic host exhibited enantioselective bonding toward the d-enantiomer of phenylalanine methyl ester hydrochloride with K D/ K L up to 6.87 in CDCl 3 with 0.25% CD 3OD.