Copper-catalyzed fluorination of 2-pyridyl aryl bromides
作者:Xin Mu、Hao Zhang、Pinhong Chen、Guosheng Liu
DOI:10.1039/c3sc51876k
日期:——
Copper(I)-catalyzed cross-coupling of aryl halides is the subject of extensive interest in synthetic chemistry, but the related catalytic fluorination is unsuccessful. Herein, we have developed a novel copper-catalyzed fluorination of aryl bromides using AgF as the fluorine source. In this transformation a pyridyl directing group is essential for successful catalytic fluorination. A XANES/EXAFS study indicated that the presence of the pyridyl group is essential to stabilize the Cu(I) species and accelerate oxidative addition of the aryl bromide. Further mechanistic studies implicated a Cu(I/III) catalytic cycle in this Cu(I)-catalyzed fluorination, and final aryl C–F bond formation possibly proceeds through an irreversible reductive elimination of the ArCu(III)–F species. This rare report of catalytic fluorination by a copper catalyst provides a valuable foundation for further development of Cu(I)-catalyzed fluorination of aryl halides.
The invention provides certain phenyl carboxamide-containing compounds of the Formula (I); or pharmaceutically acceptable salts thereof, wherein A and B are as defined herein. The invention also provides pharmaceutical compositions comprising such compounds, and methods of using the compounds for treating diseases or conditions mediated by Spleen Tyrosine Kinase (Syk) kinase.
A nickel-catalyzeddirectcross-coupling of unactivated aryl fluorides with aryl bromides is realized. The one-pot reaction, which avoids the use of preformed and sensitive organometallic reagents, proceeds effectively via C–F bond cleavage at room temperature in THF in the presence of the phosphine ligand and magnesium powder (with or without TMSCl) to produce the desired biaryls in modest to good
A process for making certain 6-aryl-2-methyl-pyridines, which are useful intermediates in the preparation of biologically active compounds, comprises
(a) subjecting a ketal of 1-hydroxy-1-aryl-5-hexanone to a Jones oxidation to yield a 1-aryl-1,5-hexanedione; or treating the 1-aryl-1-hydroxy-5-ketal-hexane with manganese dioxide in solvent to yield a ketone; and
(b) reacting the 1-aryl-1,5-hexanedione or the ketone from (a) with excess hydroxylamine hydrochloride in polar solvent at a temperature of from 50°C to 100°C.
Provided are a nitrogenous heterocyclic aromatic compound, a preparation method therefor, a pharmaceutical composition thereof, and an application thereof. The nitrogenous heterocyclic aromatic compound can be used for treating and/or preventing various diseases mediated by ALK5.