The shape of d-glucosamine

Abstract

The bioactive amino monosaccharide D-glucosamine has been generated in the gas phase via laser ablation of D-glucosamine hydrochloride. Three cyclic α-⁴C₁ pyranose forms have been identified using Fourier transform microwave techniques. Stereoelectronic hyperconjugative forces – essentially linked with the anomeric or gauche effect – and cooperative OH⋯O, OH⋯N and NH⋯O chains, extended along the entire molecule, are found to be the main factors driving the conformational behavior. The orientation of the NH₂ group within each conformer has been determined by the values of the nuclear quadrupole coupling constants. The results have been compared with those recently obtained for the archetypical D-glucose.