부산대학교 도서관

An efficient and economical one‐pot synthesis of pyrano[2,3‐c] pyrazoles and pyrazolyl‐4H‐chromenes using Water Extract of Mango Peel Ash (WEMPA) as a natural aqueous medium catalysts under microwave irradiation described. The microwave irradiation enhances the rate of the reaction, and decreases by‐product formation. The catalyst is obtained from the agro‐waste feedstock, by simple thermal treatment of dry peel of mango fruit followed by extraction of the resulted ash in water gave catalytic green solvent medium. In continuation of our research work on developing green chemistry protocol for bioactive molecule synthesis, herein, first time described pyrano[2,3‐c]pyrazole and pyrazolyl‐4H‐chromene derivative synthesis by the reaction of hydrazine hydrate (1), malononitrile (2), ethyl acetoacetate (3), aryl aldehydes (4), and/or salicylaldehyde (5). Some of the selected pyrano[2,3‐c]pyrazole (6) and pyrazolyl‐4H‐chromene (7) derivatives are tested for their in vitro antioxidant activity (free radical scavenging) by DPPH assay method. The assay result revealed, compounds 6 a, 6 h, 6 i and 7 d showed significant antioxidant activities comparison with refrence ascorbic acid. Some of the selected derivatives are characterized by FT‐IR, 1H‐, 13C‐NMR and mass spectrometry analysis, and also tested for their electrochemical behavior studies using a cyclic voltammetry. [ABSTRACT FROM AUTHOR]