Continuous Flow Photochemical Synthesis of 3-Methyl-4-arylmethylene Isoxazole-5(4H)-ones through Organic Photoredox Catalysis and Investigation of Their Larvicidal Activity

Isoxazole-5(4H)-ones are heteropentacycle compounds found in several bioactive molecules with pharmaceutical and agrochemical properties. A well-known multicomponent reaction between β-ketoester, hydroxylamine, aromatic aldehydes leads to 3-methyl-4-arylmethylene isoxazole-5(4H)-ones, mild conditions. The initial purpose of this work was investigate whether the might be induced by light, as described previous works. Remarkable results were obtained using a high-power lamp, reducing times compared methodologies that used heating or catalysis. Since there many examples successful continuous flow heterocycle synthesis, including photochemical reactions, study evolved run conditions scale up synthesis isoxazolones reactor set-up. Eight different obtained, among them, three showed larvicidal activity on immature forms Aedes aegypti tests investigated its growth inhibitory character. Mechanistic investigations indicate reactions occur through organic photoredox