Direct Electrochemical Synthesis of Sulfur‐Containing Triazolium Inner Salts

Main observation and conclusion The electrochemical thiocyanation/cyclization of aldehyde hydrazones was developed under external oxidant‐free and catalyst‐free conditions. In contrast to previous thiocyanation, this electrosynthetic approach enabled a cascade C—H thiocyanation/cyclization through a mild, direct electrolysis manner in an undivided cell without the additive of halogens and stoichiometric oxidants. In this protocol, commercially available and inexpensive sodium thiocyanate was used, which played a dual role as a thiocyanation reagent and electrolyte. This strategy provides expedient access to functionalized sulfur‐containing triazolium inner salts with ample scope and diverse functional group tolerance. Based on the findings of mechanistic studies, a reaction mechanism was proposed.