2-Amino-8-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)imidazo[1,2-a][1 ,3,5]-triazin-4(8H)-one monohydrate, a 2 `-deoxyguanosine analogue with an altered Watson-Crick recognition site

Abstract

The title compound, C10H12FN5O4 center dot H2O, shows an anti glycosyl orientation [chi = -123.1 (2)degrees] The 2-deoxy-2-fluoroarabino-furanosyl moiety exhibits a major C2'-endo sugar puckering (S-type, C2'-endo-C1'-exo, T-2(1)), with P = 156.9 (2)degrees and pi(m) = 36.8 (1)degrees, while in solution a predominantly N conformation of the sugar moiety is observed. The conformation around the exocyclic C4'-C5' bond is -sc (trans, gauche), with gamma = -78.3 (2)degrees. Both nucleoside and solvent molecules participate in the formation of a three-dimensional hydrogen-bonding pattern via intermolecular N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds; the N atoms of the heterocyclic moiety and the F substituent do not take part in hydrogen bonding.