Photocatalyzed Decarboxylative Annulation of N- Arylglycines with Cyclopropenones: Synthesis of Highly Functionalized Pyrrol-2-Ones

Herein, we developed a novel protocol for the visible-light-catalyzed synthesis of multifunctional pyrrole-2-ones from N -arylglycines ( 1 ) and cyclopropenones ( 2 ) through decarboxylation, radical addition, and ring expansion reactions. Furthermore, this cascade reaction requires only 0.08 equivalents of 4CzIPN to facilitate the photocatalytic decarboxylation, free radical addition, and ring expansion reactions, thereby eliminating the need for any transition metal catalyst. Target compounds 3a – 3l′ were obtained in moderate to excellent yields (57%–96%) by employing 4CzIPN as the photocatalyst, NaHCO 3 as the base, and propylene carbonate (PC) as the green solvent under an argon atmosphere with blue light irradiation for 3 h. The reaction does not require any metal catalyst or heating, has a wide substrate scope, is environmentally friendly and sustainable, boasts a high atom economy, and exhibits significant regioselectivity. This strategy facilitated the synthesis of pyrrole-2-ones bearing quaternary centers with potential biological activity, expanding the applications of N -arylglycine as a C2 synthon in the construction of pyrrole-2-one frameworks via room-temperature photochemical reactions.