Room-Temperature Arylation of Arenes and Heteroarenes with Diaryl­iodonium Salts by Photoredox Catalysis

Abstract

Aryl radicals produced by irradiation of diaryliodonium salts with visible light under the catalysis of [Ru(bpy) 3 ] 2+ undergo coupling with a wide range of arenes and heteroarenes, affording various biaryls through direct C-H arylation at room temperature.

Diaryliodoniums Salts as Coupling Partners for Transition-Metal Catalyzed C- and N-Arylation of Heteroarenes

“…From this point of view, photoredox chemistry involving radical intermediates is discussed here. Since the breakdown of Sanford in 2012 who reported a photoredox palladium/iridium-catalyzed C-H arylation with diaryliodonium reagents under mild conditions [98], support for the feasibility of these photocatalytic reactions with heteroarenes is provided by few reports [99][100][101][102][103][104]. Room-temperature, visible-light photocatalysis-promoted transformations of diaryliodonium salts were described by Chatani in 2013 [99].…”

Photoarylation of Pyridines Using Aryldiazonium Salts and Visible Light: An EDA Approach

“…Classical cross-coupling reactions such as Suzuki–Miyaura, − Negishi, − Stille, ,, Hiyama, , and Kumada , have been developed (Scheme , eq b) and proved to be similarly efficient. These structures can also be synthesized by C–H activation reactions (Scheme , eq c), − oxidative cross-coupling reactions (Scheme , eq d), − and alternatively by radical-based methodologies, , which have received much attention recently in studies involving photocatalysis. − Such photocatalyzed reactions have been performed with various aryl radical precursors such as aryldiazonium − and diaryliodonium salts, , aryl carboxylic acids, benzenesulfonyl chlorides (not tested with a pyridine nucleus), arylazosulfones (tested with the pyrazolopyridine nucleus), , diazoanhydrides (with pyridine N -oxide), and halo­(hetero)­arenes − in the presence of ruthenium complexes, ,,, iridium complexes, ,, organic dyes, − ,, metal oxides, ,, and other (photo)­catalysts (Scheme ...…”

“…These structures can also be synthesized by C−H activation reactions (Scheme 1, eq c), 24−26 oxidative cross-coupling reactions (Scheme 1, eq d), 27−29 and alternatively by radical-based methodologies, 30,31 which have received much attention recently in studies involving photocatalysis. 32−39 Such photocatalyzed reactions have been performed with various aryl radical precursors such as aryldiazonium 40−49 and diaryliodonium salts, 50,51 aryl carboxylic acids, 52 benzenesulfonyl chlorides (not tested with a pyridine nucleus), 53 arylazosulfones (tested with the pyrazolopyridine nucleus), 54,55 diazoanhydrides (with pyridine N-oxide), 56 and halo(hetero)arenes 57−59 in the presence of ruthenium complexes, 41,43,44,51 iridium complexes, 50,52,57 organic dyes, [47][48][49]58,59 metal oxides, 40,42,46 and other (photo)catalysts (Scheme 1, eq e). 60,61 However, the radical arylation of arenes and heteroarenes has been achieved with only a few aryl radical precursors, even in the absence of a photocatalyst.…”

Metal-Free Amino(hetero)arylation and Aminosulfonylation of Alkenes Enabled by Photoinduced Energy Transfer

“…With the advent of visible light catalysis, it is of great significance to construct β-(hetero)­arylethylamine derivatives directly from aryl and heteroaryl radicals . To date, a variety of preactivated (hetero)­aryl radical precursors have been well exploited, including (hetero)­aryl diazonium salts, di­(hetero)­aryliodonium salts, triflates, oxime esters, and N -hydroxyphthalimide (NHP) esters . Another route is to utilize stable and commercially available substrates as radical precursors, such as (hetero)­aryl halides, carboxylic acids, and sulfonyl chlorides .…”