A (±)-Cyclocytidine Analogue with a Low-anti Conformation around the Glycosyl Bond

The crystal structure of the cytidine analogue, (±)-6,6′-anhydro-2′-deoxy-6,6′β-dihydroxycarbacytidine hydrate, (alternative name: 3-amino-7-hydroxy-6-hydroxymethyl-6,7,8,8a-tetrahydro- 1H,5aH-cyclopenta­[1′,2′:1,2]oxazolo[3,2-c]pyrimidin-1-one hydrate) C₁₀H₁₃N₃O₄·H₂O, in which the glycosyl torsion angle was fixed by cyclization between the C6′ atom of the cyclopentane ring and the C6 atom of the cytosine base with one O atom, was determined by X-ray analysis. The crystal belongs to the monoclinic space group P2₁/c and the unit cell contains four cytidine analogue and four water molecules. The terminal O5′ atom of the cytidine analogue molecule is hydrogen bonded to a water molecule. The glycosyl torsion angle is low-anti (χ = 176.3°) and the puckering of the cyclopentane ring is C3′-envelope.

-1