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

Abstract

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.