Synthesis, Characterization and In Vitro Pharmacological Screening of 3, 4-Dihydropyrimidin-2-one Derivatives

Abstract

Reaction of ethyl-6-methyl–2-oxo-4-phenyl-1, 2, 3, 4- tetrahydropyrimidin-5-carboxylates (1) with hydrazine hydrate yielded 6-methyl-2-oxo-4-phenyl-1, 2, 3, 4- tetrahydropyrimidin-5-carbohydrazide (2). These products on reaction with cyanogen bromide gave 5- (5-amino 1, 3, 4-oxadiazol-2-yl)-6-methyl-4-phenyl- 3,4-dihydropyrimidin-2 (1H)-ones (3). The resultant amino-oxadiazolylpyrimidinones were condensed with substituted aromatic aldehyde to obtain various 5-(5- {[-(4-substituted phenyl) methylidene]-amino}-1, 3, 4- oxadiazol-2-yl)-6-methyl-4-phenyl-3, 4-dihydropyrimidin- 2-one (4a-f). These products were characterized by IR, 1H NMR, mass spectra and elemental analysis. The synthesized compounds (4a-f) were evaluated for their antimicrobial activity against two gram positive and two gram negative bacteria along with two fungal species /yeast strains. All the synthesized compounds showed good antimicrobial activity. In addition, the newly synthesized compounds were screened for their antioxidant properties. The results showed that the compounds 5-{5-[(4-chlorobenzylidene)-amino]-1, 3, 4- oxadiazol – 2 –yl } -6 – methyl – 4 - phenyl-3, 4 dihydropyrimidin -2 (1H) -one (4b) and 5-{5-[(4- hydroxybenzylidene)-amino]-1,3,4-oxadiazol-2-yl}-6- methyl-4-phenyl-3,4-dihydro pyrimidin- 2 (1H)-one (4d) revealed the highest antimicrobial and antioxidant activity throughout this work.