- Copper immobilized at a covalent organic framework: An efficient and recyclable heterogeneous catalyst for the Chan-Lam coupling reaction of aryl boronic acids and amines
-
A polyimide covalent organic framework (PI-COF) with high thermal and chemical stabilities has been readily prepared from commercially available and inexpensive reagents and was employed as an effective support for heterogeneous copper. It was demonstrated that the obtained Cu@PI-COF is a highly active heterogeneous catalyst which can effectively promote the Chan-Lam coupling reaction of aryl boronic acids and amines in an open flask without the aid of any base or additive. In addition, the catalyst could be readily recovered from the reaction mixture by simple filtration and reused for at least eight cycles without any observable change in structure and catalytic activity.
- Han, Yi,Zhang, Mo,Zhang, Ya-Qing,Zhang, Zhan-Hui
-
p. 4891 - 4900
(2018/11/21)
-
- Versatile routes for synthesis of diarylamines through acceptorless dehydrogenative aromatization catalysis over supported gold-palladium bimetallic nanoparticles
-
Diarylamines are an important class of widely utilized chemicals, and development of diverse procedures for their synthesis is of great importance. Herein, we have successfully developed novel versatile catalytic procedures for the synthesis of diarylamines through acceptorless dehydrogenative aromatization. In the presence of a gold-palladium alloy nanoparticle catalyst (Au-Pd/TiO2), various symmetrically substituted diarylamines could be synthesized starting from cyclohexylamines. The observed catalysis of Au-Pd/TiO2 was heterogeneous in nature and Au-Pd/TiO2 could be reused several times without severe loss of catalytic performance. This transformation needs no oxidants and generates molecular hydrogen (three equivalents with respect to cyclohexylamines) and ammonia as the side products. These features highlight the environmentally benign nature of the present transformation. Furthermore, in the presence of Au-Pd/TiO2, various kinds of structurally diverse unsymmetrically substituted diarylamines could successfully be synthesized starting from various combinations of substrates such as (i) anilines and cyclohexanones, (ii) cyclohexylamines and cyclohexanones, and (iii) nitrobenzenes and cyclohexanols. The role of the catalyst and the reaction pathways were investigated in detail for the transformation of cyclohexylamines. The catalytic performance was strongly influenced by the nature of the catalyst. In the presence of a supported gold nanoparticle catalyst (Au/TiO2), the desired diarylamines were hardly produced. Although a supported palladium nanoparticle catalyst (Pd/TiO2) gave the desired diarylamines, the catalytic activity was inferior to that of Au-Pd/TiO2. Moreover, the activity of Au-Pd/TiO2 was superior to that of a physical mixture of Au/TiO2 and Pd/TiO2. The present Au-Pd/TiO2-catalyzed transformation of cyclohexylamines proceeds through complex pathways comprising amine dehydrogenation, imine disproportionation, and condensation reactions. The amine dehydrogenation and imine disproportionation reactions are effectively promoted by palladium (not by gold), and the intrinsic catalytic performance of palladium is significantly improved by alloying with gold. One possible explanation of the alloying effect is the formation of electron-poor palladium species that can effectively promote the β-H elimination step in the rate-limiting amine dehydrogenation.
- Taniguchi, Kento,Jin, Xiongjie,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
-
p. 2131 - 2142
(2017/03/09)
-
- Ruthenium and palladium complexes incorporating amino-azo-phenol ligands: Synthesis, characterization, structure and reactivity
-
The ligands 2-((2-aminophenyl)diazenyl)phenol, HOL1-NH2, 1a; 2-((2-aminophenyl)diazenyl)-5-methylphenol, HOL2-NH2, 1b; and 2-((2-aminophenyl) diazenyl)-5-chlorophenol, HOL3-NH2, 1c, which are abbreviated as HOL-NH2, 1, afforded the complexes of compositions [(OL-NH)Pd(PPh3)], 2, and [(OL-NH)Ru(CO)(PPh3)2], 3, upon reaction with Na2PdCl4 and Ru(CO)3(PPh3)3 respectively. In all the complexes the metals ions, Pd(II) or Ru(II), are coordinated by deprotonated ligand (OL-NH)2- in tridentate (N, N, O) fashion. X-ray structures of [(OL2-NH)Pd(PPh3)], 2b, and [(OL1-NH)Ru(CO)(PPh3)2], 3a, were determined to confirm the molecular structures. The cyclic voltammograms of [(OL-NH)Ru(CO)(PPh3)2] exhibited two quasi reversible oxidative response near 0.25 and 1.12 V vs. SCE. The nature of HOMO as obtained by DFT calculations has been inspected to have an insight into the redox orbitals. The newly synthesized [(OL-NH)Pd(PPh3)], 2a, complexes exhibited catalytic activity toward the Suzuki, Heck, Cyanation and amination reactions. Catalytic activity of complex [(OL1-NH)Ru(CO)(PPh3)2], 3a, was examined for the conversion of ketones to corresponding alcohols by transfer hydrogen reactions.
- Pattanayak, Poulami,Parua, Sankar Prasad,Patra, Debprasad,Lai,Brand?o, Paula,Felix, Vitor,Chattopadhyay, Surajit
-
p. 122 - 131
(2015/03/04)
-
- Evaluation of aromatic amination catalyzed by palladium on carbon: A practical synthesis of triarylamines
-
A heterogeneous palladium on carbon (Pd/C)-catalyzed coupling between amines and aromatic halides including aromatic chlorides has been achieved using sodium tert-butoxide (NaO-t-Bu) and 1,1′-bis(diphenylphosphino)ferrocene (dppf) as a ligand in cyclopentyl methyl ether (CPME). The use of potassium tert-butoxide (KO-t-Bu) in place of NaO-t-Bu brought about the benzyne-mediated aromatic amination even without Pd/C and dppf, giving a mixture of regioisomers when 4-substituted bromobenzenes were employed as the substrate. The combination of Pd/C, dppf, NaO-t-Bu could be utilized for the syntheses of a broad range of triarylamines by replacing CPME with mesitylene which can provide a higher reaction temperature. The Pd/C could be quantitatively recovered and reused until at least the fourth cycle without any loss in catalytic activity. The quite low leaching of palladium (1.1%) was demonstrated by an inductively coupled plasma-atomic emission spectrometric analysis.
- Monguchi, Yasunari,Kitamoto, Katsunori,Ikawa, Takashi,Maegawa, Tomohiro,Sajiki, Hironao
-
supporting information; experimental part
p. 2767 - 2777
(2009/12/08)
-
- RAPID, COST EFFECTIVE METHOD FOR SYNTHESIS OF DIARYLAMINE COMPOUNDS
-
A process for forming a diarylamine compound, including reacting an aniline and an arylbromide in the presence of a palladium ligated catalyst and a base.
- -
-
Page/Page column 8
(2008/12/05)
-
- Synthesis and reactivity of pentavalent biphenyl-2,2′-ylenebismuth derivatives
-
Phenylbiphenyl-2,2′-ylenebismuth diacetate reacted with nucleophiles under basic conditions to give modest to good yields of the C-phenylated substrates. Under copper catalysis, it reacted with hydroxy or amino groups to give the products of O- or N-phenylation. In both sets of reaction conditions, this reagent showed a reduced reactivity compared to the analogous triphenylbismuth diacetate reagent. It showed also a high regioselectivity as only the phenyl derivatives were detected and isolated. The Royal Society of Chemistry 2000.
- Fedorov, Alexey Yu.,Finet, Jean-Pierre
-
p. 3775 - 3778
(2007/10/03)
-
- Triarylbismuthane - Iodobenzene diacetate: One-pot system for copper- catalysed N-arylation under neutral conditions
-
Triarylbismuthanes react with iodobenzene diacetate in dichloromethane under mild, neutral conditions to afford triarylbismuth diacetates, which can be isolated in good yields. The reagents can also be directly used in a one- pot copper-catalysed N-arylation of anilines to give near quantitative yields of the corresponding diarylamines, except in the case of the 2- methoxyphenylbismuth derivative. N-arylation with tris(2- methoxyphenyl)bismuth diacetate was quantitative only when the reaction was performed with the pure isolated reagent.
- Combes, Sebastien,Finet, Jean-Pierre
-
p. 4313 - 4318
(2007/10/03)
-
- Chemical process
-
A process for the production of symmetrical and unsymmetrical substituted diarylamines is disclosed. The process provides said diarylamines in high yield and purity by the reaction of a salt of an arylsulfonic acid and an alkali metal salt of a primary arylamine in the presence of an inorganic alkali metal salt.
- -
-
-