Green chemoselective synthesis of thiazolo[3,2-a]pyridine derivatives and evaluation of their antioxidant and cytotoxic activities.

The green chemoselective synthesis of thiazolo[3,2-a]pyridine derivatives was achieved in water via microwave-assisted three-component reactions of malononitrile, aromatic aldehydes and 2-mercaptoacetic acid with molar ratios of 2:1:1.5 and 2:2.2:1, respectively. These compounds were subject to the experiments of antioxidant activity and cytotoxicity to carcinoma HCT-116 cells and mice lymphocytes. Nearly all of the tested compounds possessed potent capacities for scavenging free radicals. In addition, most of these compounds showed cytotoxicity to HCT-116 cells and mice lymphocytes with no selectivity. Of these, only thiazolo[3,2-a]pyridine derivative 5d suggested selective cytotoxicity to tumor cell line HCT-116 cells.