Three series of heteroaromatic analogues (twenty seven compounds) with monoketone linkers were synthesized and evaluated for their antimicrobial activity against six microbial strains. Among them, 3,5-dibenzylidene-1-[(3,5dichloro-2-hydroxyphenyl)sulfonyl]piperidin-4-one (5e) showed the best antifungal activity against Aspergillus niger and A. fumigatus. Structural elucidation of the synthesized compounds was realised based on various spectroscopic methods.

A facile synthesis of new 4,6‐dichloropyridine derivatives 5(a–f), 6(a–c), and 7(a–c) were synthesized using both conventional heating and solvent‐free microwave irradiation techniques. The results revealed that the latter method is superior to the conventional heating method. The easy work‐up of the products, rapid reaction, and mild conditions are noticeable features of this protocol. Structural elucidation of the synthesized compounds was made on the basis of various spectroscopic methods. The synthesized compounds were evaluated for their in vitro antimicrobial activity (minimum inhibitory concentration; MIC) against various microbial strains using the agar well‐diffusion method. Among the compounds, 5c showed best antimicrobial activity against most of the employed strains, especially against Staphylococcus aureus, Escherichia coli, Rhizopus arrhizus, and Candida albicans. Compounds 5a, 6a, 6c, 7a, and 7c showed significant antioxidant activity when compared to the other compounds. In addition to this, theoretical docking studies were performed for the highly potent compounds 5a, 6a, 6c, 7a, and 7c against three different drug targets belonging to the oxidoreductase family, and the results were found to be highly satisfactory.

The present research work is intended for facile and efficient green synthesis of various biologically useful potent bio-active molecules from inexpensive and readily available starting substrates under mild reaction condition. These classes of synthesized various heterocyclic compounds holds a great importance to discover newer anti-microbial, anti-oxidant and anti-cancer drugs in future prospects. Further structural modification in these structures will be of interest and may result in compounds having a better therapeutic and biological activity. Hence, this efficient green synthetic protocol and biological results of newly synthesized heterocyclic derivatives are found to be interesting lead molecules for bioactivity in the near future. It could be considered for investigation of their mode of action and for further development.