Structure of a modified cytosine: an antiviral nucleoside analog, homo-Ara-C.

Abstract

Homo-Ara-C [5'-(hydroxymethyl)-5'-deoxy-1-beta-D-arabinofuranosyl-3H- cytosine], C10H16N3O5, Mr = 258.25, P2,2,2, a = 8.261 (2), b = 19.644 (4), c = 6.993 (6) A, V = 1134.8 A3, Z = 4, Dx = 1.511 g cm-3, lambda (Cu Ka) = 1.5418 A, mu = 10.5 cm-1, F(000) = 548, T = 288 K, final R = 0.053 for 1189 observed reflections. Conformational features of the nucleoside include a glycosidic bond conformation in the anti range, a ribose moiety in the 2E [C(2')-endo] form like 5'-N3-Ara-C, 5-NO2-Ara-U and Ara-C and a C(5')-C(6') bond that is gauche to C(4')-O(4') but trans to C(4')-C(3').