A Mild, One-Pot Synthesis of 4-Quinolones via Sequential Pd-Catalyzed Amidation and Base-Promoted Cyclization
作者:Jinkun Huang、Ying Chen、Anthony O. King、Mina Dilmeghani、Robert D. Larsen、Margaret M. Faul
DOI:10.1021/ol800837z
日期:2008.6.1
A mild, one-pot synthesis of 4-quinolones is described. Under the optimal conditions, a variety of 2-substituted 4-quinolones were synthesized via sequential palladium-catalyzed amidation of 2'-bromoacetophenones followed by base-promoted intramolecular cyclization.
Mapping Dual‐Base‐Enabled Nickel‐Catalyzed Aryl Amidations: Application in the Synthesis of 4‐Quinolones
作者:Ryan T. McGuire、Travis Lundrigan、Joshua W. M. MacMillan、Katherine N. Robertson、Arun A. Yadav、Mark Stradiotto
DOI:10.1002/anie.202200352
日期:2022.3.21
AbstractThe C−N cross‐coupling of (hetero)aryl (pseudo)halides with NH substrates employing nickel catalysts and organic amine bases represents an emergent strategy for the sustainable synthesis of (hetero)anilines. However, unlike protocols that rely on photoredox/electrochemical/reductant methods within NiI/III cycles, the reaction steps that comprise a putative Ni0/II C−N cross‐coupling cycle for a thermally promoted catalyst system using organic amine base have not been elucidated. Here we disclose an efficient new nickel‐catalyzed protocol for the C−N cross‐coupling of amides and 2′‐(pseudo)halide‐substituted acetophenones, for the first time where the (pseudo)halide is chloride or sulfonate, which makes use of the commercial bisphosphine ligand PAd2‐DalPhos (L4) in combination with an organic amine base/halide scavenger, leading to 4‐quinolones. Room‐temperature stoichiometric experiments involving isolated Ni0, I, and II species support a Ni0/II pathway, where the combined action of DBU/NaTFA allows for room‐temperature amide cross‐couplings.