Considerations on the Nuclear Magnetic Resonance Spectra of Some Anomeric Tetra-O-acetyl- d -glucopyranosides

We have measured the nuclear magnetic resonance spectra (NMR) of some anomers of aryl 2,3,4,6-tetra-O-acetyl-d-glucopyranosides and found that the signal of the anomeric proton in the α-anomers could be separated from the signals due to the other protons, and that the chemical shift in fact distinctly appeared in a lower mangetic field (δ=5.95 ppm, J=3.0 to 3.5 cps) than those in alkyl 2,3,4,6-tetra-O-acetyl-d-glucopyranosides. Lower field shifts have also been observed in β-anomers, but it was impossible to determine the chemical shift exactly possibly because of the overlapping with the signals due to the other protons attached to the pyranose ring.