Supporting Electrolyte‐Free Electrochemical Oxidative C−H Sulfonylation and Thiocyanation of Fused Pyrimidin‐4‐Ones in an All‐Green Electrolytic System

Abstract

AbstractAn electrooxidative C−H functionalization is a widely accepted route to obtain sulfur‐containing arenes and heteroarenes. However, this process often involves using non‐recyclable supporting electrolytes, (co)solvents like hexafluoroisopropanol, additives like acid, or catalysts. The use of additional reagents can increase costs and waste, reducing atom efficiency. Moreover, unlike other nitrogen‐containing heterocycles, there have only been sporadic reports of electrochemical C−H functionalization in fused pyrimidin‐4‐ones, and an electrolyte‐free process has yet to be developed. This work demonstrates that such anodic coupling reactions can be performed in an all‐green electrolytic system without using such additional electrolytes or HFIP, maintaining a high atom economy. This C−H functionalization strategy utilizes inexpensive sodium sulfinates and ammonium thiocyanate as sulfonylating and thiocyanating agents in an undivided cell at a constant current, using a mixture of CH3CN/H2O as solvent at room temperature. Thus, fused pyrimidin‐4‐ones can be selectively converted into C3‐sulfonylated and ‐thiocyanated derivatives in moderate to good yields.