5-Amino-1-(2',3'-O-isopropylidene-D-ribityl)-1H-imidazole-4-carboxamide: a crystal structure with Z' = 4

The title compound, C12H20N4O5, crystallizes in the monoclinic space group P21, with four crystallographically independent molecules in the asymmetric unit. The four molecules have a very similar conformation that is basically determined by the formation of two intramolecular hydrogen bonds between the amino NH2 donors and the carbonyl and ring O-atom acceptors, forming, respectively, R(6) and R(7) ring motifs.. In the crystal, intermolecular hydrogen bonding leads to the formation of R2 2(10) ring patterns, involving one amide CONH2 donor and an imidazole N-atom acceptor. The cluster of the four independent molecules has approximate non-crystallographic C2 point symmetry. The structural analysis also shows that during the synthesis of the title compound, the reductive cleavage of the d-ribose ring of the inosine precursor proceeds stereoselectively, with retention of configuration.