title: Regioselective synthesis of indazole N1- and N2-(beta-D-ribonucleosides).
abstract: The regioselective synthesis of 4-nitroindazole N1- and N2-(beta-D-ribonucleosides) (8, 9, 1b and 2b) is described. The N1-regioisomers are formed under thermodynamic control of the glycosylation reaction [fusion reaction or Silyl Hilbert-Johnson glycosylation for 48 h (66%)], while the kinetic control (Silyl Hilbert-Johnson glycosylation for 5 h) afforded only the N2-isomer (64%). The structures of the nucleosides 1b and 2b were assigned by single crystal X-ray analyses. The 4-amino-N1-(beta-D-ribofuranosyl)-1H-indazole (3b) was obtained from the nitro nucleoside 1b by catalytic hydrogenation. Compound 3b shows fluorescence while the 4-nitroindazole nucleosides 1b and 2b do not possess this property.
authors.affiliation: Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie, Universität Osnabrück, 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
mesh_terms: D006031:Glycosylation; D007191:Indazoles / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D012263:Ribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D007191:Indazoles; D012263:Ribonucleosides