Synthetic approach to flavanones and flavones via ligand-free palladium(ii)-catalyzed conjugate addition of arylboronic acids to chromones

2012 ◽  
Vol 10 (36) ◽  
pp. 7305 ◽  
Author(s):  
Donghee Kim ◽  
Kyungrok Ham ◽  
Sungwoo Hong
Keyword(s):  
Conjugate Addition ◽  
Synthetic Approach ◽  
Arylboronic Acids ◽  
Ligand Free

scholarly journals Autocatalytic photoredox Chan-Lam coupling of free diaryl sulfoximines with arylboronic acids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cong Wang ◽  
Hui Zhang ◽  
Lucille A. Wells ◽  
Tian Liu ◽  
Tingting Meng ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom Abstraction ◽  
Coupling Reactions ◽  
Ambient Light ◽  
Environmental Friendliness ◽  
Copper Species ◽  
Arylboronic Acids ◽  
Ligand Free ◽  
Byproduct Formation ◽  
Electron Reduction

AbstractN-Arylation of NH-sulfoximines represents an appealing approach to access N-aryl sulfoximines, but has not been successfully applied to NH-diaryl sulfoximines. Herein, a copper-catalyzed photoredox dehydrogenative Chan-Lam coupling of free diaryl sulfoximines and arylboronic acids is described. This neutral and ligand-free coupling is initiated by ambient light-induced copper-catalyzed single-electron reduction of NH-sulfoximines. This electron transfer route circumvents the sacrificial oxidant employed in traditional Chan-Lam coupling reactions, increasing the environmental friendliness of this process. Instead, dihydrogen gas forms as a byproduct of this reaction. Mechanistic investigations also reveal a unique autocatalysis process. The C–N coupling products, N-arylated sulfoximines, serve as ligands along with NH-sulfoximine to bind to the copper species, generating the photocatalyst. DFT calculations reveal that both the NH-sulfoximine substrate and the N-aryl product can ligate the copper accounting for the observed autocatalysis. Two energetically viable stepwise pathways were located wherein the copper facilitates hydrogen atom abstraction from the NH-sulfoximine and the ethanol solvent to produce dihydrogen. The protocol described herein represents an appealing alternative strategy to the classic oxidative Chan-Lam reaction, allowing greater substrate generality as well as the elimination of byproduct formation from oxidants.

ChemInform Abstract: Base Promoted Highly Efficient Copper Fluorapatite Catalyzed Coupling of Phenols with Arylboronic Acids under Mild and Ligand-Free Conditions.

ChemInform ◽  
2013 ◽  
Vol 44 (16) ◽  
pp. no-no
Author(s):  
Shafeek A. R. Mulla ◽  
Suleman M. Inamdar ◽  
Mohsinkhan Y. Pathan ◽  
Santosh S. Chavan
Keyword(s):  
Arylboronic Acids ◽  
Highly Efficient ◽  
Ligand Free
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