Ultrasonic synthesis, characterization, and antibacterial evaluation of novel heterocycles containing hexahydroquinoline and pyrrole moieties

Abstract

Condensation reaction of dimedone with 2-amino-1-methyl-4,5-diphenyl-1H-pyrrole-3-carbon-itrile in ethanol containing a catalytic amount of p-toluenesulfonic acid (TsOH) afforded 2-(5,5-dimethyl- 3-oxocyclohex-1-enylamino)-1-methyl-4,5-diphe-nyl- 1H-pyrrole-3-carbonitrile. This compound was then treated with olefins, formed by Knoevenagel condensa-tion of aryl aldehydes and malononitrile, in ethanol in the presence of 1,8-diazabicyclo[ 5.4.0] undec-7-ene (DBU) as catalyst to give novel cyclic compounds in high yields. A new hexacyclic heterocyclic compound was formed when 2-hydroxybenzaldehyde was used as the aldehyde. The reactions were done using ultrasonic irradiation. The syn-thesized compounds were characterized by IR, H-1 NMR, and C-13 NMR spectra, elemental analysis and evaluated for their antibacterial activity against Gram-positive bac-teria (Staphylococcus aureus and Micrococcus luteus) and Gram-negative bacterium (Escherichia coli).