The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [ C]-labeled PET tracer celecoxib.
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http://dx.doi.org/10.1002/anie.201700417 | DOI Listing |
Acc Chem Res
October 2024
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
ConspectusChemists have long pursued harnessing light energy and photoexcitation processes for synthetic transformations. Ligand-to-metal charge transfer (LMCT) in high-valent metal complexes often triggers bond homolysis, generating oxidized ligand-centered radicals and reduced metal centers. While photoinduced oxidative activations can be enabled, this process, typically seen as photochemical decomposition, remains underexplored in catalytic applications.
View Article and Find Full Text PDFJ Phys Chem A
September 2024
North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
Advancements in photocatalysis have transformed synthetic organic chemistry, using light as a powerful tool to drive selective chemical transformations. Recent approaches have focused on metal-halide ligand-to-metal charge transfer (LMCT) photoactivated bond homolysis reactions leveraged by earth-abundant elements to generate valuable synthons for radical-mediated cross-coupling reactions. Of recent utility, oxovanadium(V) LMCT photocatalysts exhibit selective alkoxy radical generation from aliphatic alcohols upon blue light (UVA) irradiation under mild conditions.
View Article and Find Full Text PDFJ Am Chem Soc
June 2024
School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China.
Tuning the properties of materials by using external stimuli is crucial for developing versatile smart materials. Strong coupling among the order parameters within a single-phase material constitutes a potent foundation for achieving precise property control. However, cross-coupling is fairly weak in most single materials.
View Article and Find Full Text PDFJ Am Chem Soc
June 2024
Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States.
Owing to their light-harvesting properties, nickel-bipyridine (bpy) complexes have found wide use in metallaphotoredox cross-coupling reactions. Key to these transformations are Ni(I)-bpy halide intermediates that absorb a significant fraction of light at relevant cross-coupling reaction irradiation wavelengths. Herein, we report ultrafast transient absorption (TA) spectroscopy on a library of eight Ni(I)-bpy halide complexes, the first such characterization of any Ni(I) species.
View Article and Find Full Text PDFJ Phys Chem Lett
May 2024
Department of Chemistry, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States.
Photoassisted catalysis using Ni complexes is an emerging field for cross-coupling reactions in organic synthesis. However, the mechanism by which light enables and enhances the reactivity of these complexes often remains elusive. Although optical techniques have been widely used to study the ground and excited states of photocatalysts, they lack the specificity to interrogate the electronic and structural changes at specific atoms.
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