Visible-Light-Enabled Sulfonyl Radical-Triggered Cyclization Strategy for the Efficient Synthesis of Benzosultams

We introduce a green and practical visible-light-driven method to synthesize benzosultam derivatives using an eosin Y organophotocatalyst. Under ambient conditions, N-alkyl-N-propargyl arylsulfonamides react with sodium aryl sulfinates through a sulfonyl-radical-driven cyclization to produce the corresponding exocyclic benzosultams. Furthermore, these products smoothly isomerize to their endocyclic forms with a mild base. This metal-free approach is mild, versatile, and eco-friendly, providing excellent yields over a wide range of substrates.