2 `-Deoxy-7-propynyl-7-deaza-adenosine: a DNA duplex-stabilizing nucleoside

Abstract

In the title compound, 2'-deoxy-7-propynyl-7-deaza-adenosine, C14H16N4O3, the torsion angle of the N-glycosylic bond is anti [chi = -130.7 (2)degrees]. The sugar pucker of the 2'-deoxy-ribo-furanosyl moiety is C2'-endo-C3'-exo, T-2(3) (S-type), with P = 185.9 (2)degrees and tau(m) = 39.1 (1)degrees, and the orientation of the exocyclic C4'-C5' bond is -ap (trans). The 7-substituted propynyl group is nearly coplanar with the heterocyclic base moiety. Mol-ecules of the nucleoside form a layered network in which the heterocyclic bases are stacked head-to-tail with a closest distance of 3.197 (1) angstrom. The crystal structure of the nucleoside is stabilized by three inter-molecular hydrogen bonds of types N-H center dot center dot center dot O, O-H center dot center dot center dot N and O-H center dot center dot center dot O.