Anti-inflammatory and antimicrobial activity of 4,5-dihydropyrimidine-5-carbonitrile derivatives: their synthesis and spectral elucidation

Thirteen new 6-(1-H-indole-2-yl)-4-oxo-2-[2-(substituted-benzylidene)-hydrazinyl]-4,5-dihydropy-rimidine-5-carbonitrile derivatives were synthesized. The title compounds, hydrazones, were synthesized by reaction of hydrazine group of 2-hydrazinyl-4-(1-H-indole-2-yl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (2) with different substituted aromatic aldehydes using a mixture (2:8, v/v) of glacial acetic acid and alcohol. The required intermediate compound 2 was synthesized from 2-mercapto-4-(1-H-indole-2-yl)-6-oxo-1,6-dihy-dropyrimidine-5-carbonitrile 1 upon nucleophilic attack by the hydrazine hydrate. Compound 1 was synthesized by modified Biginelli condensation method using indole-3-carbaldehyde, ethyl cyanoacetate and thiourea. The compounds were evaluated for their anti-inflammatory, analgesic, ulcerogenic and antimicrobial actions. Among the newer derivatives, one compound i.e., 6-(1-H-indole-2-yl)-4-oxo-2-[2-(2,6-dichlorobenzylidene)-hydrazinyl]-4,5-dihydropyrimidine-5-carbonitrile (7) emerged as lead compound having 71.14% inhibition of edema and 12.5 microg/mL MIC against both bacterial and fungal strains.