2′-De­oxy-2-fluoro­tubercidin

In the title compound [systematic name: 7-(2-de­oxy-β-D-erythro-pentofuranos­yl)-2-fluoro-7H-pyrrolo[2,3-d]pyrimidin-2-amine], C₁₁H₁₃FN₄O₃, the conformation of the N-glycosylic bond is between anti and high-anti [χ = −110.2 (3)°]. The 2′-deoxy­ribofuranosyl unit adopts the N-type sugar pucker (₄T³), with P = 40.3° and τ_m = 39.2°. The orientation of the exocyclic C4′—C5′ bond is −ap (trans), with a torsion angle γ = −168.39 (18)°. The nucleobases are arranged head-to-head. The crystal structure is stabilized by four inter­molecular hydrogen bonds of types N—H...N, N—H...O and O—H...O.

The 7-bromo derivative of 2-amino-2'-deoxy­tubercidin fluorinated at the sugar moiety

The title compound, 2,4-diamino-5-bromo-7-(2-deoxy-2-fluoro-[beta]-D-ara­bino­furanosyl)-7H-pyrrolo[2,3-d]pyrimidine, C₁₁H₁₃BrFN₅O₃, shows two conformations of the exocyclic C4'-C5' bond, with the torsion angle [gamma] (O5'-C5'-C4'-C3') being 170.1 (3)° for conformer 1 (occupancy 0.69) and 60.7 (7)° for conformer 2 (occupancy 0.31). The N-glycosylic bond exhibits an anti conformation, with [chi] = -114.8 (4)°. The sugar pucker is N-type (C3'-endo; ³T₄), with P = 23.3 (4)° and [tau]_m = 36.5 (2)°. The compound forms a three-dimensional network that is stabilized by several inter­molecular hydrogen bonds (N-H...O, O-H...N and N-H...Br).