Anodic Oxidation of Ketone Allylhydrazones into the Corresponding Azines

Abstract

Several ketone allylhydrazones were electrochemically oxidized in methanol in the presence of sodium methoxide and potassium iodide to afford the corresponding azines. The electro-oxidation involves formation of a new carbon–nitrogen double bond between an allylic carbon atom and the nitrogen atom of a hydrazone to afford a conjugated system. Optimal yields were obtained when 0.5 equivalents of sodium methoxide and a catalytic amount of potassium iodide were used as the supporting electrolyte at room temperature. Presumably, the electro-oxidation involves a two-electron oxidation process where the iodide ion functions as electron carrier.

Keywords:

• Allylhydrazones
• azines
• conjugated system
• dehydrogenation
• electro-oxidation
• ketone hydrazones

Notes

^a Substrate 1a: 10 mmol, MeOH: 40 mL, constant current: 0.3 A, current passed: 2.2 F mol⁻¹, rt: ca. 15 °C.

^b Determined by GC analysis.

^a Substrate 1: 10 mmol, KI: 2 mmol, NaOMe: 5 mmol, MeOH: 40 mL, constant current: 0.3 A, rt: ca. 15 °C.

^b Isolated yield.