168558-34-7Relevant academic research and scientific papers
An Improved PIII/PV=O-Catalyzed Reductive C-N Coupling of Nitroaromatics and Boronic Acids by Mechanistic Differentiation of Rate- And Product-Determining Steps
Li, Gen,Nykaza, Trevor V.,Cooper, Julian C.,Ramirez, Antonio,Luzung, Michael R.,Radosevich, Alexander T.
supporting information, p. 6786 - 6799 (2020/04/30)
Experimental, spectroscopic, and computational studies are reported that provide an evidence-based mechanistic description of an intermolecular reductive C-N coupling of nitroarenes and arylboronic acids catalyzed by a redox-active main-group catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide, i.e., 1·[O]). The central observations include the following: (1) catalytic reduction of 1·[O] to PIII phosphetane 1 is kinetically fast under conditions of catalysis; (2) phosphetane 1 represents the catalytic resting state as observed by 31P NMR spectroscopy; (3) there are no long-lived nitroarene partial-reduction intermediates observable by 15N NMR spectroscopy; (4) the reaction is sensitive to solvent dielectric, performing best in moderately polar solvents (viz. cyclopentylmethyl ether); and (5) the reaction is largely insensitive with respect to common hydrosilane reductants. On the basis of the foregoing studies, new modified catalytic conditions are described that expand the reaction scope and provide for mild temperatures (T ≥ 60 °C), low catalyst loadings (≥2 mol%), and innocuous terminal reductants (polymethylhydrosiloxane). DFT calculations define a two-stage deoxygenation sequence for the reductive C-N coupling. The initial deoxygenation involves a rate-determining step that consists of a (3+1) cheletropic addition between the nitroarene substrate and phosphetane 1; energy decomposition techniques highlight the biphilic character of the phosphetane in this step. Although kinetically invisible, the second deoxygenation stage is implicated as the critical C-N product-forming event, in which a postulated oxazaphosphirane intermediate is diverted from arylnitrene dissociation toward heterolytic ring opening with the arylboronic acid; the resulting dipolar intermediate evolves by antiperiplanar 1,2-migration of the organoboron residue to nitrogen, resulting in displacement of 1·[O] and formation of the target C-N coupling product upon in situ hydrolysis. The method thus described constitutes a mechanistically well-defined and operationally robust main-group complement to the current workhorse transition-metal-based methods for catalytic intermolecular C-N coupling.
Development of an aryl amination catalyst with broad scope guided by consideration of catalyst stability
McCann, Scott D.,Reichert, Elaine C.,Arrechea, Pedro Luis,Buchwald, Stephen L.
supporting information, p. 15027 - 15037 (2020/10/13)
We have developed a new dialkylbiaryl monophosphine ligand, GPhos, that supports a palladium catalyst capable of promoting carbon-nitrogen cross-coupling reactions between a variety of primary amines and aryl halides; in many cases, these reactions can be carried out at room temperature. The reaction development was guided by the idea that the productivity of catalysts employing BrettPhos-like ligands is limited by their lack of stability at room temperature. Specifically, it was hypothesized that primary amine and N-heteroaromatic substrates can displace the phosphine ligand, leading to the formation of catalytically dormant palladium complexes that reactivate only upon heating. This notion was supported by the synthesis and kinetic study of a putative off-cycle Pd complex. Consideration of this off-cycle species, together with the identification of substrate classes that are not effectively coupled at room temperature using previous catalysts, led to the design of a new dialkylbiaryl monophosphine ligand. An Ot-Bu substituent was added ortho to the dialkylphosphino group of the ligand framework to improve the stability of the most active catalyst conformer. To offset the increased size of this substituent, we also removed the para i-Pr group of the non-phosphorus-containing ring, which allowed the catalyst to accommodate binding of even very large α-tertiary primary amine nucleophiles. In comparison to previous catalysts, the GPhos-supported catalyst exhibits better reactivity both under ambient conditions and at elevated temperatures. Its use allows for the coupling of a range of amine nucleophiles, including (1) unhindered, (2) five-membered-ring N-heterocycle-containing, and (3) α-tertiary primary amines, each of which previously required a different catalyst to achieve optimal results.
A method for preparing aromatic amine derivative
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Paragraph 0116-0119, (2016/10/08)
The invention discloses a preparation method of a diarylamine ramification. The preparation method comprises the following steps: dissolving a phenylamine ramification, a phenylhydrazine ramification, a metal phthalocyanine ramification and a copper salt into a solvent, and reacting at -10 to 40 DEG C to obtain the diarylamine ramification. According to the preparation method, the phenylamine ramification and the phenylhydrazine ramification are taken as starting materials, so that raw materials are easy to obtain and plenty in variety; a product obtained by utilizing the method is plenty in type, can not only be directly used, but also be used for other further reactions; and no additive is required to be added. The preparation method disclosed by the invention has the advantages of short synthetic route, moderation in reaction condition, simple reaction operation and post-processing process, high yield and suitability for large-scale production.
CoPc/Cu(OAc)2-catalyzed N-arylation of amines with arylhydrazines leading to N-aryl amines
Sun, Wang-Bin,Zhang, Pei-Zhi,Jiang, Tao,Li, Cheng-Kun,An, Li-Tao,Shoberu, Adedamola,Zou, Jian-Ping
, p. 6477 - 6483 (2016/09/23)
The N-arylation of amines with arylhydrazines has been developed, achieving the selective cross-coupling of aryl radicals with amines to form N-aryl amines. The reaction uses air as an oxidant, CoPc and Cu(OAc)2as catalysts. The reaction proceeds under mild conditions in air through a relay process, arylhydrazines are oxidized to aryldiazenes by CoPc, further oxidized to aryl radicals by air (O2), which are trapped by Cu(OAc)2–amine complex, followed by reduction–elimination reaction to form N-aryl amines. Arylamines and arylhydrazines give the highest yields, but N-aryl-N-alkylamines and N-alkylamines can be used as well.
Heterogeneous aromatic amination of aryl halides with arylamines in water with PS-PEG resin-supported palladium complexes
Hirai, Yoshinori,Uozumi, Yasuhiro
supporting information; experimental part, p. 1788 - 1795 (2011/04/16)
Catalytic aromatic amination is achieved in water under heterogeneous conditions by the use of immobilized palladium complexes coordinated with the amphiphilic polystyrene-poly-(ethylene glycol) resin-supported di(tert-butyl)phosphine ligand. Aromatic amination of aryl halides with diphenylamine and N,N-double arylation of anilines with bromobenzene were found to proceed in water with broad substrate tolerance to give the triarylamines in high yield with high recyclability of the polymeric catalyst beads. Very little palladium leached from the polymeric catalyst under the waterbased reaction conditions to provide a green and clean (metal-uncontaminated) protocol for the preparation of triarylamines, including the optoelectronically active N,N,N',N'-tetraaryl-1,1'-biphenyl-4,4'-diamines (TPDs).
