N-O chemistry for antibiotics: discovery of N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds as selective antibacterial agents using nitroso Diels-Alder and ene chemistry

J Med Chem. 2011 Oct 13;54(19):6843-58. doi: 10.1021/jm200794r. Epub 2011 Sep 15.

Abstract

The discovery, syntheses, and structure-activity relationships (SAR) of a new family of heterocyclic antibacterial compounds based on N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds are described. A structurally diverse library of ∼100 heterocyclic molecules generated from Lewis acid-mediated nucleophilic ring-opening reactions with nitroso Diels-Alder cycloadducts and nitroso ene reactions with substituted alkenes was evaluated in whole cell antibacterial assays. Compounds containing the N-alkyl-N-(pyridin-2-yl)hydroxylamine structure demonstrated selective and potent antibacterial activity against the Gram-positive bacterium Micrococcus luteus ATCC 10240 (MIC(90) = 2.0 μM or 0.41 μg/mL) and moderate activity against other Gram-positive strains including antibiotic resistant strains of Staphylococcus aureus (MRSA) and Enterococcus faecalis (VRE). A new synthetic route to the active core was developed using palladium-catalyzed Buchwald-Hartwig amination reactions of N-alkyl-O-(4-methoxybenzyl)hydroxylamines with 2-halo-pyridines that facilitated SAR studies and revealed the simplest active structural fragment. This work shows the value of using a combination of diversity-oriented synthesis (DOS) and parallel synthesis for identifying new antibacterial scaffolds.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkenes / chemical synthesis
  • Alkenes / chemistry
  • Anti-Bacterial Agents / chemical synthesis*
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology
  • Colony Count, Microbial
  • Crystallography, X-Ray
  • Drug Resistance, Bacterial
  • Gram-Positive Bacteria / drug effects
  • Hydroxylamines / chemical synthesis*
  • Hydroxylamines / chemistry
  • Hydroxylamines / pharmacology
  • Microbial Sensitivity Tests
  • Molecular Structure
  • Nitroso Compounds / chemical synthesis*
  • Nitroso Compounds / chemistry
  • Pyridines / chemical synthesis*
  • Pyridines / chemistry
  • Pyridines / pharmacology
  • Stereoisomerism
  • Structure-Activity Relationship

Substances

  • Alkenes
  • Anti-Bacterial Agents
  • Hydroxylamines
  • Nitroso Compounds
  • Pyridines