7-Deaza-2'-deoxy-7-propynylguanosine.

The title compound, C14H16N4O4, adopts the anti conformation at the glycosylic bond [chi -117.1 (5) degrees]. The sugar pucker of the 2'-deoxyribofuranosyl moiety is C2'-endo-C3'-exo, 2T3 (S-type). The orientation of the exocyclic C4'-C5' bond is +sc (gauche). The propynyl group is linear and coplanar with the nucleobase moiety. The structure of the compound is stabilized by several hydrogen bonds (N-H...O and O-H...O), leading to the formation of a multi-layered network. The nucleobases, as well as the propynyl groups, are stacked. This stacking might cause the extraordinary stability of DNA duplexes containing this compound.