Visible‐Light‐Induced Radical Cascade Cyclization: Synthesis of (20S)‐Camptothecin, SN‐38 and Irinotecan

Abstract (20 S )‐Camptothecin, irinotecan and SN‐38 were successfully synthesized by a photocatalyzed radical cascade cyclization from an N ‐propargyl iodopyridinone and an arylisonitrile under visible light with a ruthenium catalyst. This synthetic method provided a useful entry into composing camptothecin family of antitumor agents in good yields under mild reaction conditions without the use of heavy metal reagents.