Electrochemical tandem cyclization to access sulfonylated fused sultams via SO2 insertion with sodium metabisulfite

An electrochemical three-component transformation between N-cyanamide alkene, Na2S2O5 and sulfonyl hydrazide is described, through which various sulfonylated fused sultams were prepared in a sustainable and modular fashion. In this process, cost-effective and easy-to-handle sodium metabisulfite was employed as a SO2 surrogate to form N-S and S-C bonds for the construction of fused sultams in an undivided electrolysis cell without a supporting electrolyte. The broad substrate scope, available reaction components and sustainable reaction conditions enabled this electrochemical method to efficiently broaden the chemical space for the construction of cyclic sulphonamides.

Automated summary

An electrochemical three-component transformation was developed for the synthesis of sulfonylated fused sultams using N-cyanamide alkene, Na2S2O5, and sulfonyl hydrazide. The reaction proceeds in an undivided electrolysis cell without a supporting electrolyte, utilizing cost-effective and easy-to-handle sodium metabisulfite as a SO2 surrogate. This sustainable and modular approach allows for the efficient construction of cyclic sulphonamides with a broad substrate scope and available reaction components.