Novel C2-symmetric chiral 18-crown-6 derivatives with two aromatic sidearms as chiral NMR discriminating agents

Novel C2-symmetric chiral 18-crown-6 derivatives with two aromatic sidearms 2-4 were prepared, and their enantiomeric recognition abilities as chiral NMR discriminating agents towards primary ammonium salts were examined. Among these chiral crown ethers, the most effective enantiomeric discrimination of racemic ammonium salts in the 1H NMR spectra was attained by the derivative with two pyrenylmethyl sidearms.