Fluorinated biphenyls from aromatic arylations with pentafluorobenzenediazonium and related cations. Competition between arylation and azo coupling
作者:Dmitry Kosynkin、T. Michael Bockman、Jay K. Kochi
DOI:10.1039/a701745f
日期:——
High yields of the mixed perfluorinated biaryls (C6F5–Ar) are obtained by the catalytic dediazoniation of the pentafluorobenzenediazonium salt (C6F5N2+BF4–) in acetonitrile solutions containing various aromatic substrates (ArH) together with small amounts of iodide salts. Activated (electron-rich) as well as deactivated (electron-poor) arenes are successfully pentafluorophenylated by this method. The arylation is distinct from the azo coupling of the same substrates, which takes place in the absence of the iodide catalyst and yields the corresponding diazene (C6F5NN–Ar) as product. The catalytic role of iodide, and the isomeric product distributions obtained with this procedure indicate that the arylation proceeds via the pentafluorophenyl radical in a efficient homolytic chain process. Since azo coupling involves electrophilic aromatic substitution of electron-rich ArH by C6F5N2+, the two competing pathways are distinct and do not have reactive intermediates in common.
The influence of the nature of phosphine ligand on palladium catalysts for cross-coupling of weakly nucleophilic potassium pentafluorophenyltrifluoroborate with ArHal and PhCH2Hal (Hal=Br, Cl)
作者:Anton Yu. Shabalin、Nicolay Yu. Adonin、Vadim V. Bardin、Valentin N. Parmon
DOI:10.1016/j.tet.2014.04.019
日期:2014.6
the nature of bulky phosphines used as ligands. As a result, conditions for involving the electron-deficient organoboron reagent—potassium pentafluorophenyltrifluoroborate—in the palladium-catalyzed cross-coupling with aryl bromides and arylchlorides were identified. It was demonstrated that the chosen conditions are appropriate for the reaction of K[C6F5BF3] with benzyl chloride and benzyl bromide
Highly efficient heterogeneous copper-catalyzed decarboxylative cross-coupling of potassium polyfluorobenzoates with aryl halides leading to polyfluorobiaryls
作者:Yang Lin、Mingzhong Cai、Zhiqiang Fang、Hong Zhao
DOI:10.1039/c7ra05711c
日期:——
reaction of potassium polyfluorobenzoates with aryl iodides and bromides was achieved in diglyme or DMAc at 130 or 160 °C in the presence of 10–20 mol% of a 1,10-phenanthroline-functionalized MCM-41-immobilized copper(I) complex, [MCM-41-Phen-CuI], yielding a variety of polyfluorobiaryls in good to excellent yields. This heterogeneous copper(I) complex could easily be prepared via a simple procedure
with various substituted benzoic acids is developed. The reaction is compatible with both electron-rich and electron-poor benzoic acids. It can also be extended to the synthesis of polyfluoro-substituted biaryls using polyfluorobenzenes as the starting materials.
Homolytic reactions of perfluoroaromatic compounds. Part II. Reactions of perfluorobenzoyl peroxide with aromatic compounds
作者:P. H. Oldham、Gareth H. Williams
DOI:10.1039/j39700001260
日期:——
Perfluorobenzoyl peroxide decomposes in benzene and in nitrobenzene at 80° to give mainly pentafluorobiaryls and pentafluorobenzoic acid. In hexafluorobenzene the main product is a high-boiling residue, and in chloro- and bromo-benzene pentafluorobenzoic acid and phenyl pentafluorobenzoate are formed. The latter product must arise by benzoyloxylation of the halogenobenzenes at the 1-position. The results