title: Preparation of nucleosides derived from 2-nitroimidazole and D-arabinose, D-ribose, and D-galactose by the Vorbrüggen method and their conversion to potential precursors for tracers to image hypoxia.
abstract: 2-Nitroimidazole was silylated using hexaethyldisilazane and then reacted with 1-O-acetyl derivatives of D-arabinose, D-ribose, and D-galactose in acetonitrile at mild temperatures (-20 °C to rt), catalyzed by triethylsilyl triflate (Vorbrüggen conditions). The α-anomer was formed in the former case and the β-anomers in the latter two cases (highly) selectively. When D-arabinose and D-ribose were silylated with tert-butyldiphenylsilyl chloride in pyridine at the hydroxyl groups at C-5 and acetylated at the other ones in a one-pot reaction, mixtures of anomeric 1-O-acetyl derivatives were obtained. These were coupled by the Vorbrüggen method and then deblocked at C-5 and tosylated to give precursors for tracers to image hypoxia in four steps without using Hg(CN)(2) necessary for other methods. The Vorbrüggen conditions enable a shorter route to azomycin nucleoside analogues than the previous coupling procedures.
authors: Institute of Organic Chemistry, University of Vienna, Währingerstrasse 38, A-1090 Vienna, Austria.
authors: Anna
authors: A
authors: Schweifer
authors: Friedrich
authors: F
authors: Hammerschmidt
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000818:Animals; D001089:Arabinose / Q000737:chemistry; D005690:Galactose / Q000737:chemistry; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D057054:Molecular Imaging / Q000379:methods*; D009369:Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D009593:Nitroimidazoles / Q000138:chemical synthesis*; D009705:Nucleosides / Q000138:chemical synthesis*; D011849:Radioactive Tracers; D012266:Ribose / Q000737:chemistry; D012821:Silanes / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D009593:Nitroimidazoles; D009705:Nucleosides; D011849:Radioactive Tracers; D012821:Silanes; D012266:Ribose; D001089:Arabinose; D005690:Galactose; C032159:acetonitrile