Photoredox-Catalyzed Synthesis of N-Aryl γ-Lactams via Radical Addition–Cyclization Cascade

A visible-light mediated one-pot synthesis of N-aryl γ-lactams is developed following a cascade radical addition/cyclization sequence. This transition metal-free approach proceeds efficiently at room temperature, employing an organic dye as the photocatalyst. Inexpensive N-arylglycines and acrylic acid derivatives were used as the starting materials and a vast array of diversely substituted N-aryl γ-lactams were synthesized in moderate to excellent yields. Detailed mechanistic experiments and comprehensive photophysical studies elucidated a plausible reaction mechanism.