Photochemical Multicomponent Decarboxylative Radical Coupling for the Synthesis of Imidazolidine Derivatives

The 1,2,3,4‐tetraphenyl‐oxazolium cation (TPO + ) is widely utilized as a room‐temperature phosphorescent molecule and anion sensor owing to its ability to exhibit aggregation‐induced emission. However, its capability as a photocatalyst has never been examined. In this report, the positively charged core in TPO + was shown to be effective at photooxidizing substrate molecules, making it a potent photocatalyst. A series of symmetrical and unsymmetrical imidazolidine derivatives was prepared at room temperature by a photocatalytic three‐component coupling protocol. A series of photophysical studies, including Stern–Volmer analysis of excited‐state quenching and successful interception of intermediate radicals, delineate the mechanism of this coupling reaction. Such an organocatalytic pathway, along with the mild reaction conditions, represents a significant improvement over prior methods for the synthesis of imidazolidines.