Synthesis of C3-substituted Indoles in water and their anti-bacterial activities

A series of novel C3-substituted indole derivatives containing a pyridine moiety (5a–i) were successfully synthesized through multi-component reactions. The synthesis involved 3-acetylindole, various aldehydes, ethyl cyanoacetate, and ammonium acetate, with water as the solvent and NaOH as the catalyst. This method proved advantageous, offering a straightforward experimental procedure, reduced reaction times, and favorable yields, all while maintaining substrate diversity and operational simplicity under metal-free conditions for forming C–C/C–N bonds. The agar-well diffusion method's anti-bacterial activities were carried out for the synthesized compounds. It was found that 5a has shown the highest anti-bacterial activity with the lowest MIC value of 12.50 µg/mL against Escherichia coli.