De novo synthesis of 6-6-5 fused systems through electrochemical decarboxylation and radical domino additions

Highly complex fused systems are widely present in drug development. The direct electrosynthesis of fused systems through radical domino reactions features higher atom and step economy, using abundantly available starting materials and avoiding exogenous oxidants and reductants, and thus it has been in high demand and recognized as a green, powerful, and versatile synthetic tool but remains challenging because of the instability of the radical species under the electrolysis conditions and the inclusion of a quaternary ammonium salt. Herein, we developed a de novo electrosynthesis of 6-6-5 fused systems with two new rings constructed using a user-friendly undivided cell through decarboxylation and three-step radical addition under exogenous oxidant and quaternary ammonium salt free conditions. Excellent functional group, water and air compatibility was observed with good yields obtained.