2 `-Deoxy-5-propynylcytidine: a nucleoside forming two solid-state conformations

Abstract

The title compound, 4-amino-1-(2-deoxy-beta-D-erythropentofuranosyl)-5-(prop-1-ynyl)pyrimidi n-2(1H)-one, C12H15N3O4, shows two conformations in the crystalline state which differ mainly in the glycosylic bond torsion angle and the sugar pucker. Both molecules exhibit an anti glycosylic bond conformation, with torsion angles x = -135.0 (2) and -156.4 (2)degrees for molecules 1 and 2, respectively. The sugar moieties show a twisted C2'-endo sugar pucker (S-type), with P = 173.3 and 192.5 degrees for molecules 1 and 2, respectively. The crystal structure is characterized by a three-dimensional network that is stabilized by several intermolecular hydrogen bonds between the two conformers.