N-Heterocyclic nitrenium-catalyzed triple domino reaction of organic iodides for the synthesis of phthalides and δ-lactones

A triple domino reaction catalyzed by an N-heterocyclic nitrenium salt has been developed for the synthesis of phthalides and δ-lactones. This method offers operational simplicity, mild reaction conditions, readily available reagents, and excellent functional group tolerance. A wide variety of valuable phthalides and δ-lactones were synthesized in moderate to high yields. Furthermore, the scalability of the reaction was demonstrated through successful scale-up synthesis, highlighting its practical utility in organic synthesis. We have established a photoreductive radical-polar crossover strategy for synthesizing phthalides and δ-lactones from readily available starting materials, catalyzed by N-Heterocyclic nitrenium salt through a triple domino sequence.