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-carbonitrile in ethanol containing a catalytic amount of p-toluenesulfonic acid (TsOH) afforded 2-(5,5-dimethyl-3-oxocyclohex-1-enylamino)-1-methyl-4,5-diphenyl-1H-pyrrole-3-carbonitrile. This compound was then treated with olefins, formed by Knoevenagel condensation 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 synthesized compounds were characterized by IR, 1H NMR, and 13C NMR spectra, elemental analysis and evaluated for their antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus) and Gram-negative bacterium (Escherichia coli).