Convergent synthesis of polyhalogenated quinoline C-nucleosides as potential antiviral agents

J Org Chem. 2003 May 30;68(11):4170-8. doi: 10.1021/jo020643s.

Abstract

2,5,6-Trichloro-1-(beta-d-ribofuranosyl)benzimidazole (TCRB) and 2-bromo-5,6-dichloro-1-(beta-d-ribofuranosyl)benzimidazole (BDCRB) are benzimidazole nucleosides that exhibit strong and selective anti-HCMV activity. We proposed to synthesize 2-halo-6,7-dichloro-4-(beta-d-ribofuranosyl)quinolines as 6 + 6 bicyclic analogues of TCRB. The synthesis used Wittig reactions in two key steps. The first Wittig reaction coupled a fully functionalized benzene with a ribofuranose derivative to provide (Z)-6-O-(tert-butyldimethylsilyl)-1-(4,5-dichloro-2-nitrophenyl)-1,2-dideoxy-3,4-O-isopropylidene-d-allo-1-enitol (5) as the basic skeleton for the target compounds. The following electrophile-mediated intramolecular cyclization of the cis-alkene (5) was found to afford (1S,2S)-2,5-anhydro-1-bromo-6-O-(tert-butyldimethylsilyl)-1-deoxy-1-(4,5-dichloro-2-nitrophenyl)-3,4-O-isopropylidene-d-allitol (8) as the major product. This alpha-stereoselectivity was contrary to the literature precedence. A double-bond isomerization was established to be the cause of the unexpected stereochemistry. The bromo group of 8 was displaced by a hydroxyl group. Oxidation of the hydroxy group and the reduction of a phenylnitro group provided (2S)-1-(2-amino-4,5-dichlorophenyl)-2,5-anhydro-6-O-(tert-butyldimethylsilyl)-3,4-O-isopropylidene-d-allose (11), which was subjected to the second Wittig reaction with a phosphacumulene to construct 4-[5-O-(tert-butyldimethylsilyl)-2,3-O-isopropylidene-alpha-d-ribofuranosyl]-6,7-dichloroquinolin-2-one (13). Halogenation followed by deprotection of 13 and led to the synthesis of 4-(alpha-d-ribofuranosyl)-2,6,7-trichloroquinoline (17) as the major product. The 2-aminophenone alpha-nucleoside (11) was successfully anomerized to the beta-anomer (19), which led to the synthesis of the targeted 2-chloro- and 2-bromo-6,7-dichloro-4-(beta-d-ribofuranosyl)quinolines (18and 21, respectively).

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antiviral Agents / chemical synthesis*
  • Antiviral Agents / pharmacology
  • Catalysis
  • Combinatorial Chemistry Techniques*
  • Cytomegalovirus / drug effects*
  • Fibroblasts / drug effects
  • Herpesvirus 1, Human / drug effects*
  • Humans
  • Hydrocarbons, Halogenated / chemical synthesis*
  • Hydrocarbons, Halogenated / chemistry
  • Hydrocarbons, Halogenated / pharmacology
  • Indicators and Reagents
  • Inhibitory Concentration 50
  • KB Cells / drug effects
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Nucleosides / chemical synthesis*
  • Nucleosides / chemistry
  • Nucleosides / pharmacology
  • Quinolines / chemical synthesis*
  • Quinolines / chemistry
  • Quinolines / pharmacology
  • Stereoisomerism

Substances

  • Antiviral Agents
  • Hydrocarbons, Halogenated
  • Indicators and Reagents
  • Nucleosides
  • Quinolines