Synthesis and antibacterial activity of Schiff bases and amines derived from alkyl 2-(2-formyl-4-nitrophenoxy) alkanoates

A series of novel Schiff bases and secondary amines were obtained in good yields, as a result of the reductive amination of alkyl 2-(2-formyl-4-nitrophe-noxy) alkanoates with both aniline and 4-methoxyaniline under established mild reaction conditions. Sodium tri-acetoxyborohydride as well as hydrogen in the presence of palladium on carbon were used as efficient reducing agents of the Schiff bases, in both direct and stepwise reductive amination processes. The Schiff bases, amines, and amine hydrochlorides were designed as potential antibacterial agents, and structure-activity relationship could be established following in vitro assays against Gram-positive and Gram-negative bacteria. The minimal inhibitory concentration and zone of inhibition were also determined. In these tests, some of Schiff bases and secondary amine hydrochlorides showed moderate-to-good activity against Gram-positive bacteria, including S. aureus, M. luteus, and S. mutans.