Li, Weipeng published the artcileCooperative Au/Ag Dual-Catalyzed Cross-Dehydrogenative Biaryl Coupling: Reaction Development and Mechanistic Insight, Category: pyrazoles-derivatives, the publication is Journal of the American Chemical Society (2019), 141(7), 3187-3197, database is CAplus and MEDLINE.
In the presence of (Me2S)AuCl and AgOAc, pyrazoles such as 1-phenylpyrazole underwent chemoselective and regioselective oxidative dehydrogenative coupling reactions with fluorinated arenes and pyridines such as 2,3,5,6-tetrafluoropyridine mediated by PhI(OAc)2 in 1,4-dioxane to yield (fluoroaryl)pyrazoles such as I. The mechanism of the oxidative coupling reaction was studied by determination of the reaction kinetics, kinetic isotope effects, and deuterium exchange, by generation and preparation of gold and silver complexes as potential intermediates, and by DFT calculations of transition state structures and energies for arene metalation, transmetalation, and reductive elimination reactions. Silver acetate is determined to be is the actual catalyst for C-H activation of electron-poor arenes, rather than gold(I) complexes. A mechanism of gold/silver dual catalysis is proposed, in which silver is responsible for the activation of electron-poor fluoroarenes via a concerted metalation-deprotonation pathway, and gold is responsible for the activation of electron-rich pyrazoles via an electrophilic aromatic substitution process. Kinetic studies reveal that C-H activation of pyrazoles by fluoroarylgold complexes is most likely the rate-limiting step.
Journal of the American Chemical Society published new progress about 1268520-92-8. 1268520-92-8 belongs to pyrazoles-derivatives, auxiliary class Other Aromatic Heterocyclic,Chloride, name is 4-Chloro-1-methyl-1H-pyrazolo[3,4-b]pyridine, and the molecular formula is C7H6ClN3, Category: pyrazoles-derivatives.
Referemce:
https://en.wikipedia.org/wiki/Pyrazole,
Pyrazoles – an overview | ScienceDirect Topics