220 MHz Nuclear Magnetic Resonance Studies of Amygdalin and Some Related Compounds

Abstract

Abstract A study of amygdalin, isoamygdalin, vicianin, amygdalinamide, amygdalinic acid, prunasin, sambunigrin, taxiphyllin, dhurrin, and holocalin has been carried out by nuclear magnetic resonance (NMR) spectrometry. Using 220 MHz spectra, the glycosides were studied in dimethylsulfoxide-d6 solution and in the presence of DO and D2O. Generally the assignments permit the following classification: The non-hydroxylic protons (including the anomeric protons) and the hydroxylic protons occur in the region from about 3.0 to 5.3 ppm; the aglycone methine hydrogen falls at about 6 ppm except for amygdalinamide and amygdalinic acid; the phenyl hydrogens are in the region of about 7 ppm. The chemical shifts and coupling constants for both OH6 and two H6 are independent of the aglycone stereochemistry, whereas the effect of the epimeric nature of the aglycone may be seen in terms of the carbohydrate portion resonances. The nature of the aglycone group may be classified as R or S, depending on the methine proton resonance. These studies should be very useful in the application of NMR to the recognition of aglycone stereochemistry and identification of amygdalin and other related cyanogenetic glycosides.