21382-99-0Relevant articles and documents
Alcohol promoted N -methylation of anilines with CO2/H2over a cobalt catalyst under mild conditions
Han, Buxing,Ke, Zhengang,Li, Ruipeng,Liu, Zhimin,Tang, Minhao,Wang, Huan,Zeng, Wei,Zhao, Yanfei
, p. 9147 - 9153 (2021/11/30)
N-Methylation of amines with CO2/H2 to N-methylamines over non-noble metal catalysts is very interesting but remains challenging. Herein, we present an alcohol (e.g., ethanol) promoted strategy for the N-methylation of anilines with CO2/H2 with high efficiency under mild conditions (e.g., 125 °C), which is achieved over a cobalt catalytic system composed of Co(OAc)2·4H2O, triphos and Sn(OTf)2. This catalytic system has a broad substrate scope and is tolerant toward a wide range of anilines and N-methyl anilines, and a series of N,N-dimethyl anilines were obtained in high yields. Mechanism investigation indicates that the alcohol solvent shifts the equilibrium of CO2 hydrogenation by forming an alkyl formate, which further reacts with the amine to produce N-formamide, and Sn(OTf)2 promotes the deoxygenative hydrogenation of N-formamides to afford N-methylamines. This is the first example of the N-methylation of amines with CO2/H2 over a cobalt catalytic system, which shows comparable performance to the reported Ru catalysts and may have promising applications.
Additive-freeN-methylation of amines with methanol over supported iridium catalyst
Liu, Xiang,Loh, Teck-Peng,Qiang, Wenwen,Wang, Jing,Ye, Sen,Zhu, Longfei
, p. 3364 - 3375 (2021/06/06)
An efficient and versatile zinc oxide-supported iridium (Ir/ZnO) catalyst was developed to catalyze the additive-freeN-methylation of amines with methanol. Mechanistic studies suggested that the high catalytic reactivity is rooted in the small sizes (1.4 nm) of Ir nanoparticles and the high ratio (93%) of oxidized iridium species (IrOx, Ir3+and Ir4+) on the catalyst. Moreover, the delicate cooperation between the IrOxand ZnO support also promoted its high reactivity. The selectivity of this catalyticN-methylation was controllable between dimethylation and monomethylation by carefully tuning the catalyst loading and reaction solvent. Specifically, neat methanol with high catalyst loading (2 mol% Ir) favored the formation ofN,N-dimethylated amine, while the mesitylene/methanol mixture with low catalyst loading (0.5 mol% Ir) was prone to producing mono-N-methylated amines. An environmentally benign continuous flow system with a recycled mode was also developed for the efficient production ofN-methylated amines. With optimal flow rates and amine concentrations, a variety ofN-methylamines were produced with good to excellent yields in this Ir/ZnO-based flow system, providing a starting point for the clean and efficient production ofN-methylamines with this cost-effective chemical process.
Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions
Cui, Zhibing,Liu, Jianguo,Liu, Qiying,Ma, Longlong,Singh, Thishana,Wang, Chenguang,Wang, Nan,Zhu, Yuting
supporting information, p. 7387 - 7397 (2020/11/19)
The primary objective of many researchers in chemical synthesis is the development of recyclable and easily accessible catalysts. These catalysts should preferably be made from Earth-abundant metals and have the ability to be utilised in the synthesis of pharmaceutically important compounds. Amines are classified as privileged compounds, and are used extensively in the fine and bulk chemical industries, as well as in pharmaceutical and materials research. In many laboratories and in industry, transition metal catalysed reductive amination of carbonyl compounds is performed using predominantly ammonia and H2. However, these reactions usually require precious metal-based catalysts or RANEY nickel, and require harsh reaction conditions and yield low selectivity for the desired products. Herein, we describe a simple and environmentally friendly method for the preparation of thin graphene spheres that encapsulate uniform Ni/NiO nanoalloy catalysts (Ni/NiO?C) using nickel citrate as the precursor. The resulting catalysts are stable and reusable and were successfully used for the synthesis of primary, secondary, tertiary, and N-methylamines (more than 62 examples). The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, and H2 under very mild industrially viable and scalable conditions (80 °C and 1 MPa H2 pressure, 4 h), offering cost-effective access to numerous functionalized, structurally diverse linear and branched benzylic, heterocyclic, and aliphatic amines including drugs and steroid derivatives. We have also demonstrated the scale-up of the heterogeneous amination protocol to gram-scale synthesis. Furthermore, the catalyst can be immobilized on a magnetic stirring bar and be conveniently recycled up to five times without any significant loss of catalytic activity and selectivity for the product.
Expedient Synthesis of N-Methyl- and N-Alkylamines by Reductive Amination using Reusable Cobalt Oxide Nanoparticles
Senthamarai, Thirusangumurugan,Murugesan, Kathiravan,Natte, Kishore,Kalevaru, Narayana V.,Neumann, Helfried,Kamer, Paul C. J.,Jagadeesh, Rajenahally V.
, p. 1235 - 1240 (2018/02/09)
N-Methyl- and N-alkylamines represent important fine and bulk chemicals that are extensively used in both academic research and industrial production. Notably, these structural motifs are found in a large number of life-science molecules and play vital roles in regulating their activities. Therefore, the development of convenient and cost-effective methods for the synthesis and functionalization of amines by using earth-abundant metal-based catalysts is of scientific interest. In this regard, herein we report an expedient reductive amination process for the selective synthesis of N-methylated and N-alkylated amines by using nitrogen-doped, graphene-activated nanoscale Co3O4-based catalysts. Starting from inexpensive and easily accessible nitroarenes or amines and aqueous formaldehyde or aldehydes in the presence of formic acid, this cost-efficient reductive amination protocol allows the synthesis of various N-methyl- and N-alkylamines, amino acid derivatives, and existing drug molecules.
The coupling reactions of aryl halides and phenols catalyzed by palladium and MOP-type ligands
Zhang, Yi,Ni, Gang,Li, Chengjun,Xu, Sheng,Zhang, Zhaoguo,Xie, Xiaomin
, p. 4927 - 4932 (2015/06/23)
Palladium-catalyzed coupling reactions of aryl halides and phenols are described employing the bulky and electron-rich MOP-type ligands. When K3PO4 was used as base and toluene as solvent, the catalyst system exhibited high efficiency for the coupling reaction of the activated aryl halides. When NaH was used as base and o-xylene as solvent, unactivated aryl halides can be used as substrates.
N-Demethylation of N,N-Dimethylanilines by the benzotriazole N-Oxyl radical: Evidence for a two-step electron transfer-proton transfer mechanism
Baciocchi, Enrico,Bietti, Massimo,Lanzalunga, Osvaldo,Lapi, Andrea,Raponi, Daniele
supporting information; experimental part, p. 1378 - 1385 (2010/06/11)
"Chemical Equation Presented" The reaction of the benzotriazole N-oxyl radical (BTNO) with a series of 4-X-N,N-dimethylanilines (X = CN, CF 3, CO2CH2CH3, CH3, OC6H5, OCH3) has been investigated in CH 3CN. Product analysis shows that the radical, 4-X-C6H 4N(CH3)CH2·, is first formed, which can lead to the N-demethylated product or the product of coupling with BTNO. Reaction rates were found to increase significantly by increasing the electron-donating power of the aryl substituents (p+ = -3.8). With electron-donating substituents (X = CH3, OC6H5, OCH3), no intermolecular deuterium kinetic isotope effect (DKIE) and a substantial intramolecular DKIE are observed. With electron-withdrawing substituents (X = CN, CF3, CO2CH2CH 3), substantial values of both intermolecular and intramolecular DKIEs are observed. These results can be interpreted on the basis of an electron-transfer mechanism from the N,N-dimethylanilines to the BTNO radical followed by deprotonation of the anilinium radical cation (ET-PT mechanism). By applying the Marcus equation to the kinetic data for X = CH3, OC 6H5, OCH3 (rate-determining ET), a reorganization energy for the ET reaction was determined (λ BTNO/DMA= 32.1 kcal mol- 1). From the self-exchange reorganization energy for the BTNO/BTNO- couple, a self-exchange reorganization energy value of 31.9 kcal mol-1 was calculated for the DMA·+/DMA couple.
Design and synthesis of novel dihydroquinoline-3-carboxylic acids as HIV-1 integrase inhibitors
Sechi, Mario,Rizzi, Giuseppe,Bacchi, Alessia,Carcelli, Mauro,Rogolino, Dominga,Pala, Nicolino,Sanchez, Tino W.,Taheri, Laleh,Dayam, Raveendra,Neamati, Nouri
experimental part, p. 2925 - 2935 (2009/09/05)
Previously, we discovered linomide analogues as novel HIV-1 integrase (IN) inhibitors. Here, to make possible structure-activity relationships, we report on the design and synthesis of a series of substituted dihydroquinoline-3-carboxylic acids. The crystal structure of the representative compound 2c has also been solved. Among the eight new analogues, 2e showed a potency in inhibiting IN strand transfer catalytic activity similar to the reference diketo acid inhibitor L-731,988 (IC50 = 0.9 μM vs. 0.54 μM, for 2e and L-731,988, respectively). Furthermore, none of the compounds showed significant cytotoxicity in two tested cancer cell lines. These compounds represent an interesting prototype of IN inhibitors, potentially involved in a metal chelating mechanism, and further optimization is warranted.
A kinetic study of the reaction of N,N-dimethylanilines with 2,2-diphenyl-1-picrylhydrazyl Radical: A Concerted Proton-Electron Transfer?
Baciocchi, Enrico,Calcagni, Alessandra,Lanzalunga, Osvaldo
, p. 4110 - 4115 (2008/09/21)
(Chemical Equation Presented) The reactivity of the 2,2-diphenyl-1- picrylhydrazyl radical (dpph?) toward the N-methyl C-H bond of a number of 4-X-substituted-N,N-dimethylanilines (X = OMe, OPh, CH3, H) has been investigated in MeCN, in the absence and in the presence of Mg(ClO4)2, by product, and kinetic analysis. The reaction was found to lead to the N-demethylation of the N,N-dimethylaniline with a rate quite sensitive to the electron donating power of the substituent (ρ+ = -2.03). With appropriately deuterated N,N-dimethylanilines, the intermolecular and intramolecular deuterium kinetic isotope effects (DKIEs) were measured with the following results. Intramolecular DKIE [(k H/kD)intra] was found to always be similar to intermolecular DKIE [(kH/kD)inter]. These results suggest a single-step hydrogen transfer mechanism from the N-C-H bond to dpph? which might take the form of a concerted proton-electron transfer (CPET). An electron transfer (ET) step from the aniline to dpph ? leading to an anilinium radical cation, followed by a proton transfer step that produces an α-amino carbon radical, appears very unlikely. Accordingly, a rate-determining ET step would require no DKIE or at least different inter and intramolecular isotope effects. On the other hand, an equilibrium-controlled ET is not compatible with the small slope value (-0.22 kcal-1 K-1) of the log kH/ΔG° plot. Furthermore, the reactivity increases by changing the solvent to the less polar toluene whereas the reverse would be expected for an ET mechanism. In the presence of Mg2+, a strong rate acceleration was observed, but the pattern of the results remained substantially unchanged: inter and intramolecular DKIEs were again very similar as well as the substituent effects. This suggests that the same mechanism (CPET) is operating in the presence and in the absence of Mg2+. The significant rate accelerating effect by Mg2+ is likely due to a favorable interaction of the Mg2+ ion with the partial negatively charged α-methyl carbon in the polar transition state for the hydrogen transfer process.