620-93-9Relevant articles and documents
Studies on the amination of aryl chlorides with a monoligated palladium catalyst: Kinetic evidence for a cooperative mechanism
Jimeno, Ciril,Christmann, Ute,Escudero-Adan, Eduardo C.,Vilar, Ramon,Pericas, Miquel A.
, p. 16510 - 16516 (2012)
Combined spectroscopic, crystallographic, and kinetic studies of the mechanism of aromatic amination with the efficient dinuclear Pd precatalyst [Pd2Cl(μ-Cl)PtBu2(Bph-Me)] (Bph-Me=2′-methyl-[1, 1'-biphenyl]-2-yl) have revealed overlapping, yet cooperative, mechanistic scenarios, the relative weights of which are strongly influenced by the products formed as the reaction proceeds. The stability and evolution of the precatalyst in solution has been studied and several metalation pathways that point to a single monoligated intermediate have been identified. Our work sheds light on the nature of the catalytic species involved in the process and on the structure of the corresponding catalytic network. Two cycles for catalytic amination: Combined spectroscopic, crystallographic, and kinetic studies on the amination of p-chlorotoluene with p-toluidine with a monoligated Pd catalyst have revealed overlapping, yet cooperative, mechanistic scenarios, the relative weights of which are strongly influenced by the products formed as the reaction proceeds (see scheme; L=2′-methyl-[1,1'-biphenyl]-2-yl).
Improved Buchwald-Hartwig Amination by the Use of Lipids and Lipid Impurities
Bayer, Annette,Gevorgyan, Ashot,Hopmann, Kathrin H.
supporting information, (2021/11/12)
The development of green Buchwald-Hartwig aminations has long been considered challenging, due to the high sensitivity of the reaction to the environment. Here we show that food-grade and waste vegetable oils, triglycerides originating from animals, and natural waxes can serve as excellent green solvents for Buchwald-Hartwig amination. We further demonstrate that amphiphiles and trace ingredients present in triglycerides as additives have a decisive effect on the yields of Buchwald-Hartwig aminations.
Temperature-Dependent Effects of Alkyl Substitution on Diarylamine Antioxidant Reactivity
Shah, Ron,Poon, Jia-Fei,Haidasz, Evan A.,Pratt, Derek A.
, p. 6538 - 6550 (2021/05/29)
Alkylated diphenylamines are among the most efficacious radical-trapping antioxidants (RTAs) for applications at elevated temperatures since they are able to trap multiple radical equivalents due to catalytic cycles involving persistent diphenylnitroxide and diphenylaminyl radical intermediates. We have previously shown that some heterocyclic diarylamine RTAs possess markedly greater efficacy than typical alkylated diphenylamines, and herein, report on our efforts to identify optimal alkyl substitution of the scaffold, which we had found to be the ideal compromise between reactivity and stability. Interestingly, the structure-activity relationships differ dramatically with temperature: para-alkyl substitution slightly increased reactivity and stoichiometry at 37 and 100 °C due to more favorable (stereo)electronic effects and corresponding diarylaminyl/diarylnitroxide formation, while ortho-alkyl substitution slightly decreased both reactivity and stoichiometry. No such trends were evident at 160 °C; instead, the compounds were segregated into two groups based on the presence/absence of benzylic C-H bonds. Electron spin resonance spectroscopy indicates that increased efficacy was associated with lesser diarylnitroxide formation, and deuterium-labeling suggests that this is due to abstraction of the benzylic H atom, precluding nitroxide formation. Computations predict that this reaction path is competitive with established fates of the diarylaminyl radical, thereby minimizing the formation of off-cycle products and leading to significant gains in high-temperature RTA efficacy.
Selective primary aniline synthesis through supported Pd-catalyzed acceptorless dehydrogenative aromatization by utilizing hydrazine
Lin, Wei-Chen,Yamaguchi, Kazuya,Yatabe, Takafumi
supporting information, p. 6530 - 6533 (2021/07/07)
By utilizing hydrazine (N2H4) as the nitrogen source in the presence of a hydroxyapatite-supported Pd nanoparticle catalyst (Pd/HAP), various primary anilines can be selectively synthesized from cyclohexanonesviaacceptorless dehydrogenative aromatization. The strong nucleophilicity of N2H4and the stability of the hydrazone intermediates can effectively suppress the formation of the undesired secondary aniline byproducts.
