Solid state and solution conformations of 1 -(β-D-2′,3′-secoribofuranosyl)-5,6-dichlorobenzimidazole, an acyclonucleoside analogue

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Abstract
The title compound crystallizes in the monoclinic space group P21 with 2 independent molecules in the asymmetric unit (Z = 4). The unit cell dimensions are a = 11.861(2), b= 7.897(1), c = 14.527(3) .ANG., .beta. = 91.28(1).degree.. X-ray intensity data were measured on a diffractometer, and the crystal structure was determined by direct methods. Least-squares refinement converged at R = 0.036 for 2980 reflections. The glycosidic torsion angle [C(2).sbd.N(1).sbd.C(1'').sbd.O(1'')] is 53.9.degree. in molecule A and 129.8.degree. in molecule B. In both molecules, the orientation of C(1'').sbd.O(1'') to C(2'').sbd.O(2'') is trans. The conformations about C(3'').sbd.C(4'') and C(4'').sbd.C(5'') are different in each of the 2 molecules. These features are compared with those of acyclonucleoside analog with antiviral activity. The conformation in aqueous medium was examined with the aid of high-resolution 1H NMR spectroscopy, and the results are compared with those obtained from the X-ray analysis.