2 `-Deoxyimmunosine: a thiazolo-[4,5-d]pyrimidine nucleoside adopting the syn conformation

Abstract

The title compound [ systematic name: 5-amino-3-(2-deoxy-beta- D-erythro-pentofuranosyl) thiazolo[ 4,5-d] pyrimidine-2,7- (3H, 6H)-dione], C10H12N4O5S, exhibits a syn glycosylic bond conformation, with a torsion angle chi of 61.0 (3)degrees. The furanose moiety adopts the N-type sugar pucker (T-3(4)), with P = 33.0 (5)degrees and tau(m) = 15.1 (1)degrees. The conformation at the exocyclic C4'-C5' bond is ap (trans), with the torsion angle gamma = 176.71 (14)degrees. The extended structure is a three-dimensional hydrogen-bond network involving O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds.