Microwave-assisted one-pot synthesis of tetrahydrobenzo[b]pyrans in the presence of WEWFPA and their electrochemical studies

The present work described one-pot three-component synthesis of tetrahydro benzo[b]pyran derivatives using Water Extract of Watermelon Fruit Peel Ash (WEWFPA) as a inexpensive grener catalyst. The title compounds were synthesized via the condensation reaction of aromatic aldehyde, dimedone, and ethyl cyanoacetate under microwave irradiation in agro-waste solvent medium and ethanol as a co-solvent. The developed method is simple, rapidity, high yields, pure, low cost, mild reaction condition, evading use of toxic metals and solvent, and the catalyst reusability are the main advantages. The resulting products were isolated by simple workup and recrystallization gave pure compounds. Further, the oxidation and reduction potential of the selected tetrahydrobenzo [b]pyran derivatives were studied using cyclic voltammetry.