title: Regioisomeric 4-nitroindazole N1- and N2-(beta-D-ribonucleosides).
abstract: The structures of the isomeric nucleosides 4-nitro-1-(beta-D-ribofuranosyl)-1H-indazole, C(12)H(13)N(3)O(6), (I), and 4-nitro-2-(beta-D-ribofuranosyl)-2H-indazole, C(12)H(13)N(3)O(6), (II), have been determined. For compound (I), the conformation of the glycosylic bond is anti [chi = -93.6 (6) degrees ] and the sugar puckering is C2'-exo-C3'-endo. Compound (II) shows two conformations in the crystalline state which differ mainly in the sugar pucker; type 1 adopts the C2'-endo-C3'-exo sugar puckering associated with a syn base orientation [chi = 43.7 (6) degrees ] and type 2 shows C2'-exo-C3'-endo sugar puckering accompanied by a somewhat different syn base orientation [chi = 13.8 (6) degrees ].
authors.affiliation: Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie, Universität Osnabrück, Barbarastrasse 7, 49069 Osnabrück, Germany. frank.seela@uni-osnabrueck.de
authors.forename: Frank
authors.initials: F
authors.lastname: Seela
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Peng
authors.forename: Henning
authors.initials: H
authors.lastname: Eickmeier
authors.forename: Hans
authors.initials: H
authors.lastname: Reuter
mesh_terms: D007536:Isomerism; D012263:Ribonucleosides / Q000737:chemistry*
chemical_list: D012263:Ribonucleosides