4-Amino-7-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-fluoro-7H-pyrrolo [2,3-d]pyrimidine: a bis-fluorinated analogue of 2 `-deoxytubercidin

Abstract

The title compound, C11H12F2N4O3, exhibits an anti glycosylic bond conformation, with a torsion angle chi =-117.8 ( 2) degrees. The sugar pucker is N-type (C4'-exo, between T-3(4) and E-4, with P = 45.3 degrees and tau(m) = 41.3 degrees). The conformation around the exocyclic C - C bond is -ap ( trans), with a torsion angle gamma = -177.46 ( 15) degrees. The nucleobases are stacked head-to-head. The crystal structure is characterized by a three-dimensional hydrogen-bond network involving N - H center dot center dot center dot O, O - H center dot center dot center dot O and O - H center dot center dot center dot N hydrogen bonds.