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The combined electrolysis of barbituric acids and benzylidenemalononitriles or benzylidenecyanoacetates in methanol in an undivided cell in the presence of sodium bromide results in efficient MIRC (Michael-initiated ring-closure) formation of the corresponding spirocyclopropylbarbiturates in 45-93% yield. The electrocatalytic reaction proceeds smoothly under neutral and mild conditions with benzylidenemalononitriles or benzylidenecyanoacetates bearing both electron-donating and electron-withdrawing groups. NMR and single X-ray diffraction studies indicate that the electrocatalytic MIRC transformation of barbituric acids and benzylidenecyanoacetates results in the stereoselective formation of spirocyclopropanes with an (E)-configuration of aryl and alkoxycarboxylate substituents. The implication of electrocatalysis in the MIRC reaction strategy allows the combination of the synthetic virtues of both methods and accounts for an efficient approach to medicinally relevant spirocyclopropylbarbiturates avoiding inconvenient direct use of molecular halogen or halogenated substrates in accordance with the concepts of modern green chemistry.

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The electrocatalytic direct transformation of aldehydes and two molecules of pyrazolin-5-one in the presence of sodium iodide as a mediator in methanol in an undivided cell results in the stereoselective formation of substituted IJR*,R*)-bisIJspiro-2,4-dihydro-3H-pyrazol-3-one)cyclopropanes in 65-80% yields. Thus, a unique stereoselective cascade electrocatalytic process has been found. This novel electrocatalytic process opens an efficient and convenient way to synthesize IJR*,R*)-bisIJspiro-2,4-dihydro-3H-pyrazol-3one)cyclopropanespromising compounds for different biomedical applications. Thus, the simple mediatory system can initiate in an undivided cell under mild conditions the electrochemically induced cascade reaction of aldehydes with two molecules of pyrazolin-5-one.Catal. Sci. Technol. This journal is Scheme 1 Electrocatalytic cyclization of 4,4′-IJarylmethylene)bisIJ1Hpyrazol-5-ols) (1) into substituted bispyrazolone cyclopropanes (2).

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