New Macrocyclic Compound as Chiral Shift Reagent for Carboxylic Acids

We have prepared a novel chiral macrocyclic compound 3 from a C 2-symmetric aminonaphthol in a high yield. Enantiomeric acids have large nonequivalent chemical shifts (up to 0.80 ppm) in the presence of 3 in 1H NMR (500 MHz) spectra. Quantitative analyses of a series of mandelic acids with different enantiomeric purities show that host 3 is an excellent chemical shift reagent for chiral carboxylic acids.