Visible light-induced Ni-catalyzed C–heteroatom cross-coupling of aryl halides via LMCT with DBU to access a Ni(i)/Ni(iii) cycle

Abstract

Cross-coupling of aryl halides with nucleophiles is a synthetically attractive strategy to construct C–heteroatom bonds. Here we report a highly efficient photoinduced Ni-catalyzed method for the C–heteroatom cross-coupling of aryl...

Photogenerated Ni(I)–Bipyridine Halide Complexes: Structure–Function Relationships for Competitive C(sp2)–Cl Oxidative Addition and Dimerization Reactivity Pathways

“…Photoredox catalysis has captivated the fields of organic and inorganic chemistry, with nickel­(II)–bipyridine (bpy) aryl halide complexes retaining a prominent place as the metal–ligand scaffold of choice for numerous cross-coupling reactivity pathways. − Among these, C–C and C–heteroatom couplings have been facilitated by Ni­(II)–bpy complexes through either the use of an external photosensitizer (e.g., Ir­(ppy) 3 ) or via direct excitation of the Ni­(II)–bpy aryl halide complex. − Due to the diverse reactivity and intriguing photophysics of these complexes, much interest has been placed on understanding the underlying photophysical and thermal processes involved in photoredox-mediated cross-coupling reactivity. − …”

Exploring visible light for carbon–nitrogen and carbon–oxygen bond formationvianickel catalysis

“…In 2022, Cheng and Jiang groups reported a 420 nm LED facilitated Ni-catalyzed C–N cross-coupling reaction of aryl iodides (Scheme 14). 78 With NiBr 2 · glyme as the catalyst, dtbbpy as the ligand and DBU as the base, this protocol enabled the C–N bond-forming reactions with a wide range of nitrogen-based nucleophiles, including amines, amides, and sulphonamides. Both electron-poor and -rich aryl iodides worked with high efficiency.…”

Ground- and Excited-State Structure and Spin State of a Nickel-Bipyridine Photocatalyst Revealed by X-ray Absorption Spectroscopy

“…These photosensitizers can also undergo energy transfer to the TM complex, forming excited states via indirect light excitation pathways that have enhanced reactivity in comparison to the ground-state catalysts [6][7][8] . In some cases, the specific bond-forming process occurs with direct photoexcitation of the metal center and its tunable ligand system, eliminating the need for an exogenous, precious metal photosensitizer to absorb light [9][10][11][12][13][14][15][16][17][18][19] . These properties provide the opportunity to access previously elusive or unknown mechanistic pathways and enable the invention of a wide variety of nontraditional bond constructions in medicinal chemistry, natural product synthesis, and polymerization reactions 8,[20][21][22] .…”

“…TM complexes based on earth-abundant Ni(II) and featuring the bidentate 2,2′-bipyridine (bpy) ligand have received significant attention in the field of photoredox and light-promoted catalysis in recent years 11,14,18,19,46,47 . The ground spin states and structures of Ni(II) d 8 complexes are highly dependent on the ligand field.…”