Catalyst-Free Electro-photochemical Hydroalkylation of N -Aryl Maleimides via Alternate Electrode Electrolysis: A Sustainable Route to N -Aryl Succinimides with Quaternary Center

We report a dual electrochemical-photochemical platform that enables selective hydroalkylation of N-aryl maleimides for the construction of C4-functionalized N-aryl succinimides in the presence of alcohol (as a solvent) and aryl diazo esters. Alternate electrode electrolysis (AEE) selectively promotes electrochemical reduction of N-aryl maleimides which undergoes cyclopropanation with a carbene (generated by blue LED irradiation of diazo esters), subsequent ketyl radical-mediated ring opening, and electro-oxidative nucleophilic attack by alcohol afford the densely substituted hydroalkylated succinimide derivative. No cross-reactivity or degradation of intermediates was observed. The protocol showcases high functional group tolerance, affording over 26 structurally diverse N-aryl succinimide derivatives, including the late-stage functionalization of aromatic amine-containing pharmaceutical scaffolds. A gram-scale synthesis underscores the scalability and operational simplicity of the process. Control experiments highlight the orthogonal yet complementary nature of the activation modes and provide mechanistic evidence supporting a stepwise paired electrolysis process aided with photochemical carbene generation pathway.