330-83-6Relevant academic research and scientific papers
Cu(I)–N-heterocyclic carbene-catalyzed base free C–N bond formation of arylboronic acids with amines and azoles
Zhang, Maoyuan,Xu, Zengbing,Shi, Dabin
, (2020/12/25)
A new N-heterocyclic carbene (NHC) precursor of imidazolium chloride and its corresponding Cu(I)–NHC complex 1 was synthesized. The complex 1 was found to be a highly effective catalyst for Chan-Evans-Lam coupling of arylboronic acid with amines and azoles (including imidazole, pyrazole and triazole), without addition of base at room temperature. Various substituents on three substrates can be tolerated, giving the desired coupling products in good to excellent yields (62–94%). The method is practical and offers an alternative to the corresponding copper-catalyzed Chan-Evans-Lam process for the construction of C–N bonds.
Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions
Walker, Benjamin R.,Manabe, Shuhei,Brusoe, Andrew T.,Sevov, Christo S.
supporting information, p. 6257 - 6265 (2021/05/07)
Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
Reductive C?N Coupling of Nitroarenes: Heterogenization of MoO3 Catalyst by Confinement in Silica
Yang, Fu,Dong, Xuexue,Shen, Yang,Liu, Mengting,Zhou, Hu,Wang, Xuyu,Li, Lulu,Yuan, Aihua,Song, Heng
, p. 3413 - 3421 (2021/07/31)
The construction of C?N bonds with nitroaromatics and boronic acids using highly efficient and recyclable catalysts remains a challenge. In this study, nanoporous MoO3 confined in silica serves as an efficient heterogeneous catalyst for C?N cross-coupling of nitroaromatics with aryl or alkyl boronic acids to deliver N-arylamines and with desirable multiple reusability. Experimental results suggest that silica not only heterogenizes the Mo species in the confined mesoporous microenvironment but also significantly reduces the reaction induction period and regulates the chemical efficiency of the targeted product. The well-shaped MoO3@m?SiO2 catalyst exhibits improved catalytic performance both in yield and turnover number, in contrast with homogeneous Mo catalysts, commercial Pd/C, or MoO3 nanoparticles. This approach offers a new avenue for the heterogeneous catalytic synthesis of valuable bioactive molecules.
Electrochemical Reductive Arylation of Nitroarenes with Arylboronic Acids
Wang, Dan,Wan, Zhaohua,Zhang, Heng,Alhumade, Hesham,Yi, Hong,Lei, Aiwen
, p. 5399 - 5404 (2021/10/20)
The synthesis of diarylamine is extremely important in organic chemistry. Herein, a novel electrochemical reductive arylation of nitroarenes with arylboronic acids was developed. A variety of diarylamines were synthesized without the need for transition-metal catalysts. The reaction could be scaled up efficiently in a flow cell and several derivatization reactions were carried out smoothly. Cyclic voltammetry experiments and mechanism studies showed that acetonitrile, formic acid, and triethyl phosphite all played a role in promoting this reductive arylation transformation.
Enolizable Ketones as Activators of Palladium(II) Precatalysts in Amine Arylation Reactions
Hu, Huaiyuan,Gilliam, Ashley M.,Qu, Fengrui,Shaughnessy, Kevin H.
, p. 4127 - 4135 (2020/05/05)
Enolizable ketones have been identified as effective activators for palladium(II) precatalysts in the coupling of aryl bromides and aniline. N-arylation reactions catalyzed by [(DTBNpP)PdCl2]2 (DTBNpP = (bis(tert-butyl)neopentylphosphine) and PEPPSI-IPr precatalysts are activated by the addition of acetone, mesityl oxide, and 3-pentanone. 3-Pentanone was the most effective activator. Mechanistic studies show that acetone, 3-pentanone, and mesityl oxide reduce [(DTBNpP)PdCl2]2 in the presence of NaO-t-Bu to Pd0(DTBNpP)2
Aryl Amination Using Soluble Weak Base Enabled by a Water-Assisted Mechanism
Lau, Sii Hong,Yu, Peng,Chen, Liye,Madsen-Duggan, Christina B.,Williams, Michael J.,Carrow, Brad P.
supporting information, p. 20030 - 20039 (2021/01/01)
The amination of aryl halides has become one of the most commonly practiced C-N bond-forming reactions in pharmaceutical and laboratory syntheses. The widespread use of strong or poorly soluble inorganic bases for amine activation nevertheless complicates the compatibility of this important reaction class with sensitive substrates as well as applications in flow and automated synthesis, to name a few. We report a palladium-catalyzed C-N coupling using Et3N as a weak, soluble base, which allows a broad substrate scope that includes bromo- and chloro(hetero)arenes, primary anilines, secondary amines, and amide type nucleophiles together with tolerance for a range of base-sensitive functional groups. Mechanistic data have established a unique pathway for these reactions in which water serves multiple beneficial roles. In particular, ionization of a neutral catalytic intermediate via halide displacement by H2O generates, after proton loss, a coordinatively unsaturated Pd-OH species that can bind amine substrate triggering intramolecular N-H heterolysis. This water-assisted pathway operates efficiently with even weak terminal bases, such as Et3N. The use of a simple, commercially available ligand, PAd3, is key to this water-assisted mechanism by promoting coordinative unsaturation in catalytic intermediates responsible for the heterolytic activation of strong element-hydrogen bonds, which enables broad compatibility of carbon-heteroatom cross-coupling reactions with sensitive substrates and functionality.
Synthesis of unsymmetrically substituted triarylaminesviaacceptorless dehydrogenative aromatization using a Pd/C andp-toluenesulfonic acid hybrid relay catalyst
Jin, Xiongjie,Koizumi, Yu,Mizuno, Noritaka,Nozaki, Kyoko,Takayama, Satoshi,Yamaguchi, Kazuya,Yatabe, Takafumi
, p. 4074 - 4084 (2020/05/25)
An efficient and convenient procedure for synthesizing triarylamines based on a dehydrogenative aromatization strategy has been developed. A hybrid relay catalyst comprising carbon-supported Pd (Pd/C) andp-toluenesulfonic acid (TsOH) was found to be effective for synthesizing a variety of triarylamines bearing different aryl groups starting from arylamines (diarylamines or anilines), using cyclohexanones as the arylation sources under acceptorless conditions with the release of gaseous H2. The proposed reaction comprises the following relay steps: condensation of arylamines and cyclohexanones to produce imines or enamines, dehydrogenative aromatization of the imines or enamines over Pd nanoparticles (NPs), and elimination of H2from the Pd NPs. In this study, an interesting finding was obtained indicating that TsOH may promote the dehydrogenation.
PROSTACYCLIN RECEPTOR AGONIST
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Paragraph 0088-0090; 0101-0103, (2020/12/22)
A compound represented by formula (I) or an isomer or a pharmaceutically acceptable salt thereof. The present invention also relates to an application of the same in preparing a drug for treating a disease related to a PGI2 receptor.
Synthesis and characterization of new square planar heteroleptic cationic complexes [Ni(ii) β-oxodithioester-dppe]+; Their use as a catalyst for Chan-Lam coupling
Kumari, Kavita,Kumar, Saurabh,Singh, Krishna Nand,Drew, Michael G. B.,Singh, Nanhai
, p. 12143 - 12153 (2020/07/30)
Novel heteroleptic [Ni(ii) β-oxodithioester-dppe]+PF6- complexes (β-oxodithioester = methyl-3-hydroxy-3-benzyl-2-propenedithioate L1 1, methyl-3-hydroxy-3-(p-methoxyphenyl)-2-propenedithioate L2 2, methyl-3-hydroxy-3-(naphthyl)-2-propenedithioate L3 3, methyl-3-hydroxy-3-(p-chlorophenyl)-2-propenedithioate L4 4, methyl-3-hydroxy-3-(p-bromophenyl)-2-propenedithioate L5 5 and methyl-3-hydroxy-3-(p-cyanophenyl)-2-propenedithioate L6 6) have been synthesized and characterized by elemental (C, H, N) analysis, ESI-MS, IR, UV-visible, 1H, 13C{1H}, 31P{1H} and 19F{1H} NMR spectroscopy. The distorted square planar structures of the isomorphous cationic complexes 2, 3, 4 and 5 have been determined by X-ray crystallography. The catalytic activities of 1-6 were investigated for the Chan-Lam coupling reaction involving arylboronic acids and amines to afford N-arylated products in good to excellent yields under mild conditions with 1 mol% catalyst loading. This catalytic protocol offers significant functional group tolerance, and is endowed with a broad substrate scope. This journal is
A new copper complex on graphene oxide: A heterogeneous catalyst for N-arylation and C-H activation
Mittal, Ayushi,Kumari, Shweta,Parmanand,Yadav, Deepak,Sharma, Sunil K.
, (2019/12/15)
Graphene oxide supported Cu (II) ligand complex (GO?AP/L-Cu) has been synthesized and characterized by FT-IR, Raman, PXRD, UV–Visible, TGA, XPS, FESEM, TEM, EDAX, Elemental mapping, BET, CHNS and AAS analysis. The complex has been found to be efficient and reusable heterogeneous catalyst for the N-arylation and C-H activation reactions, both the catalytic reactions were found to be simple, cleaner and give high yields (~ 90%) of product. The catalyst can be easily filtered out from the reaction mixture and reused up to four times without significant loss of catalytic activity. The reported method is economical and novel in the sense that aqueous medium was used for both the reactions and for the stability of the catalyst. All isolated organic products were fully characterized on the basis of their physical and spectral data.
