The reaction of D-glucose with aminoguanidine

The reaction of D-glucose with aminoguanidine was examined at pH 7.0 and 37 degrees C (phosphate buffer). Under these conditions, the reaction requires ca. 42 days for 50% of the sugar to react, as measured by the disappearance of D-glucose, and at 60 degrees C all the aminoguanidine had reacted within 72 h. The initial product, a beta-D-glucopyranosyl aminoguanidine (1) was obtained in the crystalline state as the trifluoroacetate salt. Data collected on this compound suggests that, in solution, it is largely a glycosylamine in the beta pyranose form. Acetylation gave a crystalline heptaacetate (2), which, in solution (as evidenced by NMR spectroscopy) exists in two different conformational forms. The crystal structure of the heptaacetate also includes two conformers. Both crystallographically independent molecules are in the normal beta pyranose form, with the acetylated guanyl residue occupying different spatial positions relative to the ring.