5-Amino-1-(2',3'-O-iso-propyl-idene-d-ribit-yl)-1H-imidazole-4-carboxamide: a crystal structure with Z' = 4.

The title compound, C(12)H(20)N(4)O(5), crystallizes in the monoclinic space group P2(1), with four crystallographically independent mol-ecules in the asymmetric unit. The four mol-ecules have a very similar conformation that is basically determined by the formation of two intra-molecular hydrogen bonds between the amino NH(2) donors and the carbonyl and ring O-atom acceptors, forming, respectively, R(6) and R(7) ring motifs.. In the crystal, inter-molecular hydrogen bonding leads to the formation of R(2)(2)(10) ring patterns, involving one amide CONH(2) donor and an imidazole N-atom acceptor. The cluster of the four independent mol-ecules has approximate non-crystallographic C(2) 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.