Boryl Radical as a Catalyst in Enabling Intra‐ and Intermolecular Cascade Radical Cyclization Reactions: Construction of Polycyclic Molecules

• DOI: 10.1002/ange.202405863
• Publication Date: 2024-04-09T02:18:51Z
• Authors: Jie Wang; Yee Lin Phang; You‐Jie Yu; Nan‐Nan Liu; Qiang Xie; Feng‐Lian Zhang; Ji‐Kang Jin; Yi‐Feng Wang
• Keywords: Alkene; Alkyne; Moiety; Radical cyclization

Abstract Cascade radical cyclization constitutes an atom‐ and step‐economic route for rapid assembly of polycyclic molecular skeletons. Although array redox‐active metal catalysts has recently shown robust applications in enabling various catalytic cascade processes, the use free organic as catalyst, which is capable triggering strategically distinct cascades, rarely been developed. Here, we disclosed that benzimidazolium‐based N ‐heterocyclic carbene (NHC)‐boryl catalyzing reactions both intra‐ intermolecular pathways, assembling [5,5] fused bicyclic [6,6,6] tricyclic molecules, respectively. The start with chemo‐ regioselective addition boryl catalyst to a tethered alkene or alkyne moiety, followed by either intramolecular formal [3+2] [2+2+2] cycloaddition process construct bicyclo[3.3.0]octane tetrahydrophenanthridine skeletons, Eventually, β‐elimination occurs release completing cycle. High excellent diastereoselectivity achieved under substrate control.