New 3-pyridinecarbonitrile derivatives and their antimicrobial properties

2-Alkoxy-4,6-diaryl-3-pyridinecarbonitriles 2a-f were prepared through the reaction of 1,3-diaryl-2-propen-1-ones 1a-c with malononitrile in the appropriate alcohol in the presence of sodium. The reaction was assumed to take place through Michael addition followed by cyclization due to the alkoxide nucleophilic attack at one of the nitrile groups. This assumption was substantiated by isolation of the open-chain Michael adduct 4, followed by independent cyclization to the corresponding 2-alkoxy-3-pyridinecarbonitriles 2 upon treatment with the appropriate alcohol in the presence of sodium. Bromination of 4a,b with bromine in glacial acetic acid, afforded directly the corresponding 2-bromo-3-pyridinecarbonitriles 6a,b. The latters readily underwent nucleophilic substitution with different amines. The antimicrobial properties of the prepared compounds against Gram positive, Gram-negative, acid-fast bacteria and yeast were screened. Many of the prepared compounds show remarkable antimicrobial activity.