One-pot synthesis of carbazole based 3-hydroxy-4H-chromen-4-ones by modified Algar-Flynn-Oyamada reaction and their antimicrobial activity

Abstract

A new series of 2-(9-ethyl-9H-carbazol-3-yl)-3-hydroxy-4Hchromen-4-ones have been synthesized from substituted 2-hydroxy acetophenones and 9-ethyl-9H-carbazole-3-carbaldehyde using NaOH and H2O2 by modified Algar-Flynn-Oyamada reaction. In this method flavonols are synthesized without isolating chalcones in good yields (70-82%). The structures of the compounds were established on the basis of 1H-NMR, 13CNMR, FT-IR and mass spectral and analytical data. All the compounds were evaluated for their antimicrobial activity against bacteria such as Staphylococus aureus, Bacillus subtilis, Escherichia coli and Klebsiella pneumoniae as well as fungi such as Aspergillus flavus and Fusarium oxysporum.

Keywords

• 2-(9-ethyl-9H-carbazol-3-yl)-3-hydroxy-4H-chromen-4-ones
• modified Algar-Flynn-Oyamada reaction
• antimicrobial activity