NHC‐Catalyzed Radical Cross‐Claisen Condensation for Diverse β‐Keto Ester Synthesis

Comprehensive Summary The cross‐Claisen condensation is a valuable method for synthesizing β‐keto esters but is traditionally limited by the need for strong bases or preformed silyl ketene acetals (SKAs) or a narrow substrate scope. To address these challenges, we developed a mild, N ‐heterocyclic carbene (NHC)‐catalyzed radical cross‐Claisen condensation between acyl imidazoles and α‐bromo esters. This protocol employs Mn‐mediated single‐electron reduction to generate persistent ketyl and α‐carbonyl radicals, enabling efficient cross‐coupling of two electrophiles under redox‐neutral conditions. The reaction proceeds with broad functional‐group tolerance and can be conducted in a one‐pot manner directly from carboxylic acids, offering a practical platform for β‐keto ester synthesis.