Electrochemical Synthesis of Heterocyclic Compounds: X. Anodic Synthesis of s-Triazolo [3,4-a)pyridinium Salt Derivatives

A novel way of preparing s-triazolo[3,4-a] pyridinium salts by . anodic oxidation of aryl hydrazones of 2-acetylpyridine, 2-benzoylpyridine and 2-formylpyridine is described. Controlled potential electrolysis was carried out in CH3CN-Et4NX media using a Pt- electrode and a divided cell. The products were obtained in high yield (79-91°/o) and purity. It has been shown that the conformation of the starting hydrazone does not affect the yield of products and s-triazolo [3,4-a]pyridinium salts differing in anions can be prepared merely by using a supporting electrolyte carrying the desired anion (Clo4- , Tso-, BFn