Catalyst-free electro-photochemical insertion reactions of carbene anion radicals by convergent paired electrolysis

Paired electrolysis is an energy-efficient electrochemical reaction where both anodic and cathodic electron flow directly induces product formation with maximum faradaic efficiency. Herein we report a metal-free convergent pair electro-photochemical strategy to generate radical cation and anion that resulted in the N-alkylation of various N-heterocycles, amines, and sulfonamides. The strategy also facilitated site-selective CH-alkylation of benzo fused morpholine, indolines, and OH- and SH- alkylation of phenols and thiophenols with aryl diazo esters. Mild reaction condition such as 5 mA constant current and 5 W blue LED were sufficient to complete the reaction within 2 h. Late-stage and site-selective alkylation of APIs such as sulfadiazines and privileged scaffolds like sulfonamides and diazepanes have been achieved successfully. This paired photo-electrolysis strategy establishes a new energy-efficient way to achieve important reactions with better productivity and shorter reaction time over the existing strategies.