First example of a crystalline urazole nucleoside: (1R,2R)-urazole-α-D-pyranosyl-2-deoxyriboside

Article abstract of DOI:10.1107/S0108270195015873

The first example of a crystalline urazole nucleoside has been synthesized from the reaction of D-deoxyribose with urazole and characterized by X-ray crystallography as a single α-pyranoside diastereomer [IUPAC name: 1-(2-deoxy-α-D-erythro-pentopyranosyl)-1(R),2(R),4-triazolidine-3,5-dione, C₇H₁₁N₃O₅]. The pyranosyl group and H atom on the two pyramidal hydrazidic N atoms have an R,R-trans configuration, and the H atom on the trigonal imidic N atom is coplanar with the ring. Intermolecular hydrogen bonding is extensive and involves pyranose-pyranose, pyranose-urazole and urazole-urazole interactions. Each molecule is linked via eight hydrogen bonds to six surrounding molecules in which the urazole hydrazidic N(H) atom and imidic N atom are donors and carbonyl O atoms are acceptors, and the pyranose hydroxylic O atoms are donors as well as acceptors. The pyranose ring O atom does not participate in conventional hydrogen bonding but may be involved in a weak intermolecular C - H...O interaction.