Iron‐Catalyzed Radical Relay Enabling Modular Synthesis of Fused Pyridines from Alkyne‐Tethered Oximes and Alkenes

We have rationally designed a new class of alkyne-tethered oximes, and applied them into an unprecedented iron-catalyzed radical relay protocol for the rapid assembly of a wide array of structurally new and interesting fused pyridines. This method showcases broad substrate scope and good functional group tolerance, and can be applied for a few biologically active molecules. In addition, the fused pyridines can be diversely functionalized through various simple transformations, such as cyclization, C-H alkylation, and click reaction. DFT calculation studies indicate that the reactions involve cascade 1,5-hydrogen atom transfer, 5-exo-dig radical addition, and cyclization processes. Moreover, preliminary biological investigations suggest that some of the fused pyridines exhibit good anti-inflammatory activity by restoring the imbalance of inflammatory homeostasis of macrophages in a lipopolysaccharide-induced model.