1,N 6-Etheno-2 `-deoxytubercidin hemihydrate

Abstract

The title compound [systematic name: 7-(2-deoxy-beta-d-erythro-pentofuranosyl)-7H-imidazo[1,2-c]pyrrolo[2 ,3-d]pyrimidine hemihydrate], 2C(13)H(14)N(4)O(3)center dot H2O or (I)center dot 0.5H(2)O, shows two similar conformations in the asymmetric unit. These two conformers are connected through one water molecule by hydrogen bonds. The N-glycosylic bonds of both conformers show an almost identical anti conformation with chi = -107.7 (2)degrees for conformer (I-1) and -107.0 (2)degrees for conformer (I-2). The sugar moiety adopts an unusual N-type (C3'-endo) sugar pucker for 2'-deoxyribonucleosides, with P = 36.8 (2)degrees and tau(m) = 40.6 (1)degrees for conformer (I-1), and P = 34.5 (2)degrees and tau(m) = 41.4 (1)degrees for conformer (I-2). Both conformers and the solvent molecule participate in the formation of a three-dimensional pattern with a `chain'-like arrangement of the conformers. The structure is stabilized by intermolecular O-H...O and O-H...N hydrogen bonds, together with weak C-H...O contacts.