A facile synthesis of <i style="">N</i>-phenyl-6-hydroxy-3-bromo-4-arylazo quinolin-2-ones under phase transfer catalytic conditions and studies on their antimicrobial activities

Abstract

The synthesis and characterization of <i style="">N</i>-phenyl-6-hydroxy-3-bromo-4-arylazoquinolin-2-ones has been reported under phase transfer catalytic conditions in 70% yields. Interaction of <i style="">N</i>-phenyl-2,5-dihydroxy-3-arylazo indoles with dibromocarbene under phase transfer catalysis conditions at 50-60^oC and 600 r.p.m. results in a cycloaddition of the <i style="">in situ</i> generated carbene to the C=C bond followed by skeletal rearrangement in the indole frame work to yield quinoline nuclei. The structure of the compounds are established on the basis of their elemental, IR and ¹H NMR and ¹³C NMR data. All the synthesized compounds have been evaluated for their <i style="">in vitro</i> growth inhibitory activity against <i style="">Escherichia coli</i>, <i style="">Pseudomonas diminuta, Bascillus subtilis, Bacillus megaterium</i> and <i style="">Staphylococcus aureus</i>. All the compounds show significant antibacterial activity. A perusal of data reveals that molecular refractive index (M_R) is correlated linearly to the drug activity. The synthesized compounds have been subjected to acute toxicity studies to find out LD₅₀ values. The compounds do not show any toxicity up to dose of 7.5 mg/kg body weights in rats.