Synthesis and antiprotozoal evaluation of benzothiazolopyrroloquinoxalinones, analogues of kuanoniamine A

Bioorg Med Chem. 2003 Aug 5;11(16):3407-12. doi: 10.1016/s0968-0896(03)00311-0.

Abstract

Boc-aminoethylindoloquinone 8, a key intermediate for the building of pentacyclic quinoneimines, analogues of kuanoniamine A, was synthesized by alkylation of 4,7-dimethoxyindole 3 with 1,2-dibromoethane followed by transformation into azide, reduction of the latter with trimethylphosphine in the presence of 2-(tert-butoxycarbonyloximino)-2-phenylacetonitrile and oxydative demethylation of the Boc-amine 6 with silver(II) oxide. Quinone 8 was then treated in situ with the thiazole o-quinodimethane 10 to afford a regioisomeric mixture of the tetracyclic quinones 11. Treatment of the mixture with trifluoroacetic acid and molecular sieves 4-A provided the corresponding quinoneimines 12. Separation of the regioisomers was performed by preparative thin-layer chromatography on silica gel. The structural assignment was made by 2D 1H-13C HMBC correlations performed on the less polar regioisomer 12b. In vitro anti-leishmanial assays showed that the tested compounds possess a good potency towards two Leishmania sp. as well as against a virulent strain of Toxoplasma gondii and without any cytotoxicity against THP-1 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaloids / chemical synthesis*
  • Alkaloids / chemistry
  • Alkaloids / pharmacology*
  • Alkaloids / toxicity
  • Animals
  • Antiprotozoal Agents / chemical synthesis*
  • Antiprotozoal Agents / chemistry
  • Antiprotozoal Agents / pharmacology*
  • Antiprotozoal Agents / toxicity
  • Cell Line
  • Heterocyclic Compounds, 4 or More Rings / chemical synthesis*
  • Heterocyclic Compounds, 4 or More Rings / chemistry*
  • Heterocyclic Compounds, 4 or More Rings / pharmacology*
  • Humans
  • Inhibitory Concentration 50
  • Leishmania / drug effects
  • Molecular Structure
  • Toxoplasma / drug effects

Substances

  • Alkaloids
  • Antiprotozoal Agents
  • Heterocyclic Compounds, 4 or More Rings
  • kuanoniamine A