6-Aza-2 `-deoxyuridine and N-3-anisoyl-6-aza-2 `-deoxyuridine

Abstract

In 2-( 2-deoxy-beta-D-erythro-pentofuranosyl)-1,2,4-triazine3,5(2H, 4H)-dione (6-aza-2'-deoxyuridine), C8H11N3O5, (I), the conformation of the glycosylic bond is between anti and high-anti [chi = -94.0 (3)degrees], whereas the derivative 2-(2-deoxy-beta- D-erythro-pentofuranosyl)-N-4-(2-methoxybenzoyl)-1,2,4-triazine- 3,5(2H, 4H)-dione (N-3-anisoyl-6-aza-2'-deoxyuridine), C16H17N3O7, (II), displays a high-anti conformation [chi = .86.4 (3)degrees]. The furanosyl moiety in (I) adopts the S-type sugar pucker (T-2(3)), with P = 188.1 (2)degrees and tau(m) = 40.3 (2)degrees, while the sugar pucker in (II) is N (T-3(4)), with P = 36.1 (3)degrees and tau(m) = 33.5 (2)degrees. The crystal structures of (I) and (II) are stabilized by intermolecular N - H center dot center dot center dot O and O-H center dot center dot center dot O interactions.