Rice Husk Derived Activated Carbon‐Catalyzed Synthesis of Coumarin Derivatives: Study of Anti‐Cancer Activity

Abstract Herein, we report the fabrication of biomass rice husk‐derived chemically activated carbon (RCAC) sheets which are self‐assembled to 2D hollow porous materials and demonstrated their catalytic efficiency in the domino Knoevenagel−Michael addition reaction for the synthesis of various bio‐active coumarin derivatives in excellent yields under metal‐free conditions mild reaction conditions. Particularly, we have illustrated a facile, eco‐friendly, economical, and sustainable method for the synthesis of bis‐(4‐hydroxycoumarin)methanes, bis‐dimedones, and 4‐hydroxy‐3‐thiomethylcoumarins, via three‐component reactions of 4‐hydroxy coumarin/demedone, aldehydes and or thiophenols. Moreover, the Michael addition of 4‐hydroxy coumarin and chalcone derivatives leading to the synthesis of warfarin derivatives has also been demonstrated using RCAC as a catalyst. The cytotoxicity potential has been performed against human liver cancer cell line Hep‐G2 cancer cells for all the synthesized products by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) method. The cytotoxicity study against Hep‐G2 results indicates that all compounds are capable of killing the liver cancer cell line. The most potent anti‐proliferative activity was observed in compounds 3 g , 5 b , 5 c , 5 a , and 9 b against liver cancer cells.