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

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.

Novel Cyclopentenoid Cyanohydrin Rhamnoglucosides from Flacourtiaceae1

“…These changes indicate that the rhamnosyl residue is bound to this site. Closely similar glycosidation-induced shifts have been observed in other cyanohydrin glycosides (12)(13)(14)(15)(16); conversion of flavonoid 3-Dglucopyranosides into 6'-O-cz-L-rhamnopyranosyl derivatives (f3-rutinosides) causes downfield shift of C-6' by about 5,8 ppm and upfield shift of C-5' by about 1.4 ppm (17) (cf. Table II).…”

Synthesis and Characterisation of α‐Glycosyloxyamides Derived from Cyanogenic Glycosides

“…The in‐vitro conversion of cyanogenic glycosides into their corresponding amides using concentrated ammonia to hydrolyse the nitrile moiety has been previously reported (Turczan et al ., 1978; Takeda et al ., 1997; Jaroszewski et al ., 2004). However, with this method, the corresponding acids are formed as a major by‐product besides the low amount of the primary amides (Turczan et al.…”

“…However, with this method, the corresponding acids are formed as a major by‐product besides the low amount of the primary amides (Turczan et al. , 1978). Moreover, under these strong alkaline conditions, cyanogenic glycosides with asymmetric benzyl carbons undergo a partial stereoinversion of this carbon (Fig.…”

“…Moreover, under these strong alkaline conditions, cyanogenic glycosides with asymmetric benzyl carbons undergo a partial stereoinversion of this carbon (Fig. 2; Nahrstedt, 1975) forming epimeric mixtures of the respective primary amides and carboxylic acids during hydrolysis of the nitrile moiety (Turczan et al ., 1978). In contrast, the in‐vitro reaction of cyanogenic glycosides with hydrogen peroxide (Radziszewski reaction) allowed a complete conversion of prunasin into its corresponding α ‐glucosyloxyamide prunasinamide with conservation of its stereochemistry (Sendker and Nahrstedt, 2009).…”

“… The benzylic α ‐carbon of aromatic cyanogenic glycosides undergoes a stereoinversion when treated under alkaline conditions (Nahrstedt, 1975) as used for the nitrile hydrolysis described by Turczan et al . (1978), Takeda et al . (1997) and Jaroszewski et al .…”