Photoredox Radical Cascade Cyclization of 2‐Alkynylarylnitriles in Visible Light: Direct Access to 3‐Amino‐1‐indenones

Abstract

A photoinduced direct synthesis of 3‐amino‐1‐indenones via radical cascade cyclization strategy is demonstrated. The methodology involves a domino reaction between 2‐alkynylarylnitrile and N‐aminopyridinium salt and captures the reactivity of in‐situ generated nitrogen‐centered radical (NCR) in visible light. Multiple bond‐forming events including C‐N, C‐C, and C‐O take place sequentially on 2‐alkynylarylnitrile enabling construction of 3‐amino‐1‐indenone core at room temperature in 35‐76% yields. A preliminary biological screening of synthesized compounds is indicative of their potent anti‐cancer property.

Direct Fluorosulfonamidation of (Hetero)arenes and Alkenes with Photoredox-Active Fluorosulfamoyl Radical Reagents

“…In continuation of our keen interest in exploring radical fluorosulfonylation methodology, − we aimed to design bench-stable and readily available radical reagents to facilitate fluorosulfonamidation reactions. Drawing inspiration from recent advances in the utilization of N-functionalized pyridinium salts as versatile reagents, − we successfully synthesized the required N -fluorosulfamoyl pyridium reagents (NFSAP- 1a ) in two steps from commercially available N -aminopyridium iodide and the structure of 1a was elucidated through X-ray single-crystal diffraction (CCDC: 2353363). We envisioned that N-centered fluorosulfamoyl radicals could be generated through the cleavage of weak N-heteroatom bonds tethered to redox-active scaffolds.…”