Novel 3-alkanoyl/aroyl/heteroaroyl-2H-chromene-2-thiones: synthesis and evaluation of their antioxidant activities.

A facile, convenient and high yielding synthesis of a combinatorial library of 3-alkanoyl/aroyl/heteroaroyl-2H-chromene-2-thiones has been developed by the condensation of easily accessible beta-oxodithioesters and salicylaldehyde/substituted 2-hydroxybenzaldehydes under solvent-free conditions. The assessment of radical scavenging capacity of the compounds towards the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was measured and these compounds were found to scavenge DPPH free radical efficiently. Five selected compounds were able to protect curcumin from the attack of sulfur free radical generated by radiolysis of glutathione (GSH). The newly synthesized compounds exhibited profound antioxidant activities. Five of them rendered comparatively high antioxidant capacity.