Merging Electrochemical Synthesis and Post-Ugi Cyclization for the Synthesis of Diverse 4‑Imidazolidinones

Despite the appreciation for electro-organic synthesis, postmulticomponent reaction transformation chemistry rarely exploits this powerful technology. Herein, we explore post-Ugi cyclization reactions using N-centered radical-mediated intramolecular ipso cyclization to synthesize diverse spirocyclic variants of 4-imidazolidinones through the use of electrochemically generated amidyl radicals from the bis-amides of the Ugi adducts. This protocol features an undivided cell setup under constant-current conditions with carbon–platinum electrodes. These metal- and reagent-free reactions are scalable and have broad substrate scope.