Crystal and molecular structure of 6,2'-anhydro-1-beta-D-arabinofuranosylctyosine.

The crystal and molecular structure of the title compound has been determined by X-ray diffraction method. The compound crystallizes in monoclinic system with the space group P2₁ and Z=2; the unit cell dimensions are a=10.491, b=7.255, c=6.858 A and β=103.55°. The structure was refined to an R-index of 0.051. The glycosyl torsion angle X_CN is 111.4° (syn-anti) and the arabinose ring forms an exo-conformation, in which C(4′) is displaced by 0.61 A out of the plane of remaining four atoms. The orientation of the C(5′)O(5′) bond is the gauche-gauche as similar as that found frequently in many nucleosides.