- Copper anchored on phosphorus g-C3N4as a highly efficient photocatalyst for the synthesis ofN-arylpyridin-2-amines
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A heterogeneous photocatalyst based on copper modified phosphorus doped g-C3N4(Cu/P-CN) has been prepared and characterized. This recyclable catalyst exhibited high photocatalytic activity for the synthesis ofN-arylpyridin-2-amine derivatives by the reaction of 2-aminopyridine and aryl boronic acid at room temperature under the irradiation of blue light. Importantly, the range of substrates for this coupling reaction has been expanded to include aryl boronic acids with strong electron-withdrawing groups as viable raw materials. In addition, this heterogeneous catalyst can be used at least 6 times while maintaining its catalytic activity.
- Di, Jia-Qi,Zhang, Mo,Chen, Yu-Xuan,Wang, Jin-Xin,Geng, Shan-Shan,Tang, Jia-Qi,Zhang, Zhan-Hui
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p. 1041 - 1049
(2021/02/09)
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- Dialkylterphenyl Phosphine-Based Palladium Precatalysts for Efficient Aryl Amination of N-Nucleophiles
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A series of 2-aminobiphenyl palladacycles supported by dialkylterphenyl phosphines, PR2Ar′ (R=Me, Et, iPr, Cyp (cyclopentyl), Ar′=ArDipp2, ArXyl2f, Dipp (2,6-C6H3-(2,6-C6H3-(CHMe2)2)2), Xyl=xylyl) have been prepared and structurally characterized. Neutral palladacycles were obtained with less bulky terphenyl phosphines (i.e., Me and Et substituents) whereas the largest phosphines provided cationic palladacycles in which the phosphines adopted a bidentate hemilabile k1-P,η1-Carene coordination mode. The influence of the ligand structure on the catalytic performance of these Pd precatalysts was evaluated in aryl amination reactions. Cationic complexes bearing the phosphines PiPr2ArXyl2 and PCyp2ArXyl2 were the most active of the series. These precatalysts have demonstrated a high versatility and efficiency in the coupling of a variety of nitrogen nucleophiles, including secondary amines, alkyl amines, anilines, and indoles, with electronically deactivated and ortho-substituted aryl chlorides at low catalyst loadings (0.25–0.75 mol % Pd) and without excess ligand.
- Rama, Raquel J.,Maya, Celia,Nicasio, M. Carmen
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supporting information
p. 1064 - 1073
(2020/01/25)
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- CuI/2-Aminopyridine 1-Oxide Catalyzed Amination of Aryl Chlorides with Aliphatic Amines
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A class of 2-aminopyridine 1-oxides are discovered to be effective ligands for the Cu-catalyzed amination of less reactive (hetero)aryl chlorides. A wide range of functionalized (hetero)aryl chlorides reacted with various aliphatic amines to afford the desired products in good to excellent yields under the catalyst of CuI/2-aminopyridine 1-oxides. Furthermore, the catalyst system worked well for the coupling of cyclic secondary amines and N-methyl benzylamine with (hetero)aryl chlorides.
- Chen, Xiahong,He, Yongqiang,Liang, Yun,Liu, Wenjie,Wang, Deping,Xia, Xiaohong,Xu, Jiamin,Xu, Zhifeng,Zhang, Fuxing,Zhang, Xin
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supporting information
p. 7486 - 7490
(2020/10/12)
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- Cu/ N, N′-Dibenzyloxalamide-Catalyzed N-Arylation of Heteroanilines
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N,N′-Dibenzyloxalamide (DBO) was identified as a powerful ligand for promoting Cu-catalyzed coupling of heteroanilines with (hetero)aryl halides. For (hetero)aryl chlorides, the coupling reaction occurred at 130 °C with 5 mol % CuBr and 10 mol % DBO. For
- Chen, Zhixiang,Ma, Dawei
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supporting information
p. 6874 - 6878
(2019/09/07)
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- Direct C-H alkylation and indole formation of anilines with diazo compounds under rhodium catalysis
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The rhodium(iii)-catalyzed direct functionalization of aniline C-H bonds with α-diazo compounds is described. These transformations provide a facile construction of ortho-alkylated anilines with diazo malonates or highly substituted indoles with diazo acetoacetates.
- Mishra, Neeraj Kumar,Choi, Miji,Jo, Hyeim,Oh, Yongguk,Sharma, Satyasheel,Han, Sang Hoon,Jeong, Taejoo,Han, Sangil,Lee, Seok-Yong,Kim, In Su
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supporting information
p. 17229 - 17232
(2015/12/05)
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- Ligand free copper-catalyzed N-arylation of heteroarylamines
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An efficient protocol for ligand-free Cu-catalyzed N-arylation of heteroarylamines has been developed. With the use of 1% CuI, a wide range of aryl iodides and bromides coupled with heteroarylamines to afford the corresponding products in high yields. Further, this protocol is particularly suitable for reactions of the most hindered aryl iodides with 2-aminopyridines.
- Wang, Deping,Kuang, Daizhi,Zhang, Fuxing,Liu, Yang,Ning, Shunhua
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supporting information
p. 7121 - 7123
(2015/01/08)
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- Direct ortho arylation of 9-(pyridin-2-yl)-9 h-carbazoles bearing a removable directing group via palladium(II)-catalyzed C-H bond activation
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A one-pot synthesis of ortho-arylated 9-(pyridin-2-yl)-9H-carbazoles via C-H bond activation is presented. Silver nitrate and tert-butyl alcohol were found to be the best oxidant and solvent for the process, respectively. The product yields are from modest to excellent, and the reaction showed sufficient functional group tolerance. p-Benzoquinone served as an important ligand for the transmetalation and reductive elimination steps in the catalytic process. The key intermediate of the reaction, a 9-(pyridin-2-yl)-9H-carbazole palladacycle, was isolated, and its structure was unequivocally confirmed by X-ray crystallography. No kinetic isotope effect (kH/kD = 1.00 ± 0.17) for the C-H bond activation step was observed. In addition, a Hammett experiment gave a negative ρ value,-2.16 ± 0.02. The directing group, pyridinyl, was demonstrated to be a removable functional group. Finally, a rational catalytic mechanism is presented on the basis of all experimental evidence.
- Chu, Jean-Ho,Wu, Chung-Chiu,Chang, Deng-Hsiang,Lee, Ya-Ming,Wu, Ming-Jung
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supporting information
p. 272 - 282
(2013/02/25)
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- Palladium(II)-Catalyzed One-Pot Syntheses of 9-(Pyridin-2-yl)-9H-carbazoles through a Tandem C-H Activation/C-X (X=C or N) Formation Process
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A new one-pot synthesis of 9-(pyridin-2-yl)-9H-carbazoles through the simultaneous C-H activation and palladium(II)-catalyzed cross-coupling of N-phenylpyridin-2-amines with potassium aryltrifluoroborates is presented. Silver acetate and 1,4-dioxane proved to be the best oxidant and solvent, respectively. The product yields fluctuated from modest to excellent and the reaction showed sufficient functional group tolerance. p-Benzoquinone served as an important ligand for the transmetalation and reductive elimination steps in the catalytic process. The kinetic isotope effects (kH/kD) for the first and second C-H activation/C-C or C-N formation steps were measured as 2.14 and 1.18, respectively. Finally, a rational catalytic mechanism is presented based on all experimental evidence. Thrown together to perform: A variety of N-pyridylcarbazoles were synthesized through concurrent C-H activation/coupling of N-phenylpyridin-2-amines with potassium aryltrifluoroborates (see scheme; BQ=p-benzoquinone). The catalytic mechanism was elucidated by the examination of X-ray crystal structures of PdII intermediates and key products, as well as control experiments and kinetic isotope effect studies. Copyright
- Chu, Jean-Ho,Lin, Pi-Shan,Lee, Ya-Ming,Shen, Wei-Ting,Wu, Ming-Jung
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supporting information; experimental part
p. 13613 - 13620
(2011/12/22)
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- On the importance of an acid additive in the synthesis of pyrido[1,2-a]benzimidazoles by direct copper-catalyzed amination
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Not just an acid! An expedient and highly modular synthesis of 6-, 7-, and 8-substituted pyrido[1,2-a]benzimidazoles (4) has been developed by a direct intramolecular C-H amination of N-phenylpyridin-2-amines (3). Efficient C-H amination of 3 could only be achieved in the presence of catalytic copper and an acid additive. The type of acid (pKa) proved to be crucial for the catalysis. C-Cl aminations in N-(2-chloroaryl)pyridin-2-amines allow access to 9-substituted pyrido[1,2-a]benzimidazoles. Copyright
- Masters, Kye-Simeon,Rauws, Tom R. M.,Yadav, Ashok K.,Herrebout, Wouter A.,Van Der Veken, Benjamin,Maes, Bert U. W.
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supporting information; experimental part
p. 6315 - 6320
(2011/07/31)
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- Synthesis of N-(2-pyridyl)indoles via Pd(II)-catalyzed oxidative coupling
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Readily available Pd(II) chloride catalysts can catalyze selective and efficient oxidative coupling between N-aryl-2-aminopyridines and internal alkynes to yield N-(2-pyridyl)indoles. This process involves the ortho C-H activation of N-aryl-2-aminopyridines, and CuCl2 was used as an oxidant. Compared to our previously reported Rh(III)-catalyzed synthesis of this class of product, this method is advantageous with a wider scope of alkynes and cost-effective Pd(II) catalysts. Molecular oxygen can be used as a terminal oxidant.
- Chen, Jinlei,Pang, Qingyu,Sun, Yanbo,Li, Xingwei
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supporting information; experimental part
p. 3523 - 3526
(2011/06/24)
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- A direct intramolecular C-H amination reaction cocatalyzed by copper(II) and iron(III) as part of an efficient route for the synthesis of pyrido[1,2-a ]benzimidazoles from N-aryl-2-aminopyridines
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A novel and efficient synthesis of pyrido[1,2-a]benzimidazoles through direct intramolecular aromatic C-H amination of N-aryl-2-aminopyridines has been developed. The reaction, cocatalyzed by Cu(OAc)2 and Fe(NO 3)3?9H
- Wang, Honggen,Wang, Yong,Peng, Changlan,Zhang, Jiancun,Zhu, Qiang
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supporting information; experimental part
p. 13217 - 13219
(2010/11/04)
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- Rh(III)-catalyzed oxidative coupling of N -aryl-2-aminopyridine with alkynes and alkenes
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[RhCp*Cl2]2 (1-2 mol %) can catalyze the oxidative coupling of N-aryl-2-aminopyridines with alkynes and arylates to give N-(2-pyridyl)indoles and N-(2-pyridyl)quinolones, respectively, using Cu(OAc)2 as an oxidant. Coupling with styrenes gave mono- and/or disubstituted olefination products.
- Chen, Jinlei,Song, Guoyong,Pan, Cheng-Ling,Li, Xingwei
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supporting information; experimental part
p. 5426 - 5429
(2011/03/20)
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