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Additive-free selective methylation of secondary amines with formic acid over a Pd/In2O3 catalyst
Formic acid is used as the sole carbon and hydrogen source in the methylation of aromatic and aliphatic amines to methylamines. The reaction proceeds via a formylation/transfer hydrogenation pathway over a solid Pd/In2O3 catalyst without the need for any additive.
Benaissa, Idir,Cantat, Thibault,Genre, Caroline,Godou, Timothé,Pinault, Mathieu
p. 57 - 61
(2022/01/19)

Photochemical Reaction of N,N-Dimethylanilines with N-Substituted Maleimides Utilizing Benzaldehyde as the Photoinitiator
Photoorganocatalysis constitutes a powerful domain of photochemistry and organic synthesis. The scaffold of pyrrolo[3,4-c]quinolinoles exhibits interesting and potent inhibition against various enzymes, making them really promising pharmaceutical targets. Herein, we describe a photochemical methodology for the reaction of N,N-dimethylanilines with N-substituted maleimides, utilizing benzaldehyde as the photoinitiator. A variety of substituted N,N-dimethylanilines and N-substituted maleimides were converted into the corresponding adducts in moderate to high yields.
Nikitas, Nikolaos F.,Theodoropoulou, Maria A.,Kokotos, Christoforos G.
supporting information
p. 1168 - 1173
(2021/02/01)

Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
p. 1237 - 1242
(2021/06/01)

Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information
p. 9029 - 9039
(2021/06/28)

Dirhodium-Catalyzed Chemo-and Site-Selective C-H Amidation of N, N-Dialkylanilines
A method for dirhodium-catalyzed C(sp 3)-H amidation of N, N-dimethylanilines was developed. Chemoselective C(sp 3)-H amidation of N-methyl group proceeded exclusively in the presence of C(sp 2)-H bonds of the electron-rich aromatic ring. Site-selective C(sp 3)-H amidation proceeded exclusively at the N-methyl group of N-methyl-N-Alkylaniline derivatives with secondary, tertiary, and benzylic C(sp 3)-H bonds α to a nitrogen atom.
Chen, Gong,Arai, Kenta,Morisaki, Kazuhiro,Kawabata, Takeo,Ueda, Yoshihiro
supporting information
p. 728 - 732
(2021/01/18)

Utilization of renewable formic acid from lignocellulosic biomass for the selective hydrogenation and/or N-methylation
Lignocellulosic biomass is one of the most abundant renewable sources in nature. Herein, we have developed the utilization of renewable formic acid from lignocellulosic biomass as a hydrogen source and a carbon source for the selective hydrogenation and further N-methylation of various quinolines and the derivatives, various indoles under mild conditions in high efficiencies. N-methylation of various anilines is also developed. Mechanistic studies indicate that the hydrogenation occurs via a transfer hydrogenation pathway.
Zhou, Chao-Zheng,Zhao, Yu-Rou,Tan, Fang-Fang,Guo, Yan-Jun,Li, Yang
p. 4724 - 4728
(2021/09/06)

Photocatalytic Water-Splitting Coupled with Alkanol Oxidation for Selective N-alkylation Reactions over Carbon Nitride
Photocatalytic water splitting technology (PWST) enables the direct use of water as appealing “liquid hydrogen source” for transfer hydrogenation reactions. Currently, the development of PWST-based transfer hydrogenations is still in an embryonic stage. Previous reports generally centered on the rational utilization of the in situ generated H-source (electrons) for hydrogenations, in which photogenerated holes were quenched by sacrificial reagents. Herein, the fully-utilization of the liquid H-source and holes during water splitting is presented for photo-reductive N-alkylation of nitro-aromatic compounds. In this integrate system, H-species in situ generated from water splitting were designed for nitroarenes reduction to produce amines, while alkanols were oxidized by holes for cascade alkylating of anilines as well as the generated secondary amines. More than 50 examples achieved with a broad range scope validate the universal applicability of this mild and sustainable coupling approach. The synthetic utility of this protocol was further demonstrated by the synthesis of existing pharmaceuticals via selective N-alkylation of amines. This strategy based on the sustainable water splitting technology highlights a significant and promising route for selective synthesis of valuable N-alkylated fine chemicals and pharmaceuticals from nitroarenes and amines with water and alkanols.
Xu, Yangsen,Zhang, Zhaofei,Qiu, Chuntian,Chen, Shaoqin,Ling, Xiang,Su, Chenliang
p. 582 - 589
(2020/12/09)

Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2for consecutiveN-methylation of amines
A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2leading to consecutive doubleN-methylation of primary amines in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). A wide range of secondary amines and primary amines were successfully methylated under mild conditions. The catalyst sustained over six successive cycles ofN-methylation of secondary amines without compromising its activity, which encouraged us to check its efficacy towards doubleN-methylation of primary amines. Moreover, this method was utilized for the synthesis of two commercially available drug molecules. A detailed mechanistic cycle was proposed by performing a series of control reactions along with the successful characterisation of active catalytic intermediates either by single-crystal X-ray study or by NMR spectroscopic studies in association with DFT calculations.
Das, Arpan,Maji, Subir,Mandal, Swadhin K.
p. 12174 - 12180
(2021/09/28)

Alcohol promoted N -methylation of anilines with CO2/H2over a cobalt catalyst under mild conditions
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.
Han, Buxing,Ke, Zhengang,Li, Ruipeng,Liu, Zhimin,Tang, Minhao,Wang, Huan,Zeng, Wei,Zhao, Yanfei
p. 9147 - 9153
(2021/11/30)

Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
We report herein that a borane-trimethylamine complex worked as an efficient reducing agent for the selective methylation and formylation of amines with 1 atm CO2 under metal-free conditions. 6-Amino-2-picoline serves as a highly efficient catalyst for the methylation of various secondary amines, whereas in its absence, the formylation of primary and secondary amines was achieved in high yield with high chemoselectivity. Mechanistic studies suggest that the 6-amino-2-picoline-borane catalytic system operates like an intramolecular frustrated Lewis pair to activate CO2.
Zhang, Yanmeng,Zhang, He,Gao, Ke
supporting information
p. 8282 - 8286
(2021/10/25)

Nickel-Catalyzed Amination of Aryl Chlorides with Amides
A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
supporting information
p. 687 - 691
(2021/01/09)

Preparation method of N-alkylated derivative of primary amine compound
The invention relates to a preparation method of an N-alkylated derivative of a primary amine compound. The method comprises the following steps: uniformly mixing a primary amine compound, an alcohol compound and a catalyst in a reactor, and heating to react for a period of time to generate an N-alkylated substituted tertiary amine compound; wherein the catalyst is a copper-cobalt bimetallic catalyst, and the carrier of the catalyst is Al2O3. According to the method, alcohol is adopted as an alkylating reagent and is low in price and easy to obtain, a byproduct is water, no pollution is caused to the environment, and the overall reaction atom economy is high; the catalyst is simple in preparation method, low in cost, high in reaction activity and good in structural stability; meanwhile, by using the copper-cobalt bimetallic catalyst, the use of strong base additives can be avoided, and the requirement on reaction equipment is low; and the reaction post-treatment is convenient, and the catalyst can be recycled and is environment-friendly.
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Paragraph 0021; 0038

(2021/07/09)

Method for realizing N-alkylation by using alcohols as carbon source under photocatalysis
The invention discloses a method for realizing N-alkylation by using alcohols as a carbon source under photocatalysis, and belongs to the technical field of catalytic synthesis. Alcohol, a substrate raw material and a catalyst are placed in a reaction device, ultraviolet and/or visible light irradiation is carried out in an inert atmosphere, after the irradiation is finished, solid-liquid separation is carried out to remove the catalyst, and an N-alkylation product can be obtained through extraction, distillation and purification, wherein the substrate raw material comprises any one of an amine compound, an aromatic nitro compound or an aromatic nitrile compound, the alcohol comprises any one or more of soluble primary alcohols, and the catalyst is metal oxide/titanium dioxide or metal sulfide/titanium dioxide. The method is simple and easy to operate, can be used for efficient photocatalysis one-pot multi-step hydrogenation N-alkylation reaction, and is mild in reaction condition, high in chemical selectivity of N-alkylamine, good in catalyst stability and easy to recycle.
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Paragraph 0048-0057

(2021/03/13)

Additive-freeN-methylation of amines with methanol over supported iridium catalyst
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.
Liu, Xiang,Loh, Teck-Peng,Qiang, Wenwen,Wang, Jing,Ye, Sen,Zhu, Longfei
p. 3364 - 3375
(2021/06/06)

CO2-tuned highly selective reduction of formamides to the corresponding methylamines
We herein describe an efficient, CO2-tuned and highly selective C-O bond cleavage of N-methylated formanilides. With easy-to-handle and commercially available NaBH4 as the reductant, a variety of formanilides could be turned into the desired tertiary amines in moderate to excellent yields. The role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments.
Chao, Jianbin,Guo, Zhiqiang,Pang, Tengfei,Wei, Xuehong,Xi, Chanjuan,Yan, Leilei
supporting information
p. 7534 - 7538
(2021/10/12)

Visible-Light-Induced C(sp2)-C(sp3) Cross-Dehydrogenative-Coupling Reaction of N-Heterocycles with N-Alkyl- N-methylanilines under Mild Conditions
Disclosed herein is a cross-dehydrogenative-coupling reaction of N-heterocycles including 1,2,4-triazine-3,5(2H, 4H)-diones and quinoxaline-2(1H)-ones with N-methylanilines to form C(sp2)-C(sp3) under visible-light illumination and ambient air at room temperature. In this process, easily available Ru(bpy)3Cl2·6H2O serves as the catalyst, and air acts as the green oxidant. This method features high atom economy, environmental friendliness, and convenient operation and provides an efficient and practical access to aminomethyl-substituted N-heterocycles with extensive functional group compatibility in 40-86% yields.
Zhang, Hong-Yu,Chen, Jianjun,Lu, Cong-Cong,Han, Ya-Ping,Zhang, Yuecheng,Zhao, Jiquan
p. 11723 - 11735
(2021/09/02)

Trialkylammonium salt degradation: Implications for methylation and cross-coupling
Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
p. 6949 - 6963
(2021/06/02)

Simple RuCl3-catalyzed N-Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol
Methanol is a potential hydrogen source and C1 synthon, which finds interesting applications in both chemical synthesis and energy technologies. The effective utilization of this simple alcohol in organic synthesis is of central importance and attracts scientific interest. Herein, we report a clean and cost-competitive method with the use of methanol as both C1 synthon and H2 source for selective N-methylation of amines by employing relatively cheap RuCl3.xH2O as a ligand-free catalyst. This readily available catalyst tolerates various amines comprising electron-deficient and electron-donating groups and allows them to transform into corresponding N-methylated products in moderate to excellent yields. In addition, few marketed pharmaceutical agents (e. g., venlafaxine and imipramine) were also successfully synthesized via late-stage functionalization from readily available feedstock chemicals, highlighting synthetic value of this advanced N-methylation reaction. Using this platform, we also attempted tandem reactions with selected nitroarenes to convert them into corresponding N-methylated amines using MeOH under H2-free conditions including transfer hydrogenation of nitroarenes-to-anilines and prepared drug molecules (e. g., benzocaine and butamben) as well as key pharmaceutical intermediates. We further enable one-shot selective and green syntheses of 1-methylbenzimidazole using ortho-phenylenediamine (OPDA) and methanol as coupling partners.
Sarki, Naina,Goyal, Vishakha,Tyagi, Nitin Kumar,Puttaswamy,Narani, Anand,Ray, Anjan,Natte, Kishore
p. 1722 - 1729
(2021/04/19)

Simplified preparation of a graphene-co-shelled Ni/NiO@C nano-catalyst and its application in theN-dimethylation synthesis of amines under mild conditions
The development of Earth-abundant, reusable and non-toxic heterogeneous catalysts to be applied in the pharmaceutical industry for bio-active relevant compound synthesis remains an important goal of general chemical research.N-methylated compounds, as one of the most essential bioactive compounds, have been widely used in the fine and bulk chemical industries for the production of high-value chemicals. Herein, an environmentally friendly and simplified method for the preparation of graphene encapsulated Ni/NiO nanoalloy catalysts (Ni/NiO@C) was developed for the first time, for the highly selective synthesis ofN-methylated compounds using various functional amines and aldehydes under easy to handle, and industrially applicable conditions. A large number of primary and secondary amines (more than 70 examples) could be converted to the correspondingN,N-dimethylamines with the participation of different functional aldehydes, with an average yield of over 95%. A gram-scale synthesis also demonstrated a similar yield when compared with the benchmark test. In addition, it was further proved that the catalyst could easily be recycled because of its intrinsic magnetism and reused up to 10 times without losing its activity and selectivity. Also, for the first time, the tandem synthesis ofN,N-dimethylamine products in a one-pot process, using only a single earth-abundant metal catalyst, whose activity and selectivity were more than 99% and 94%, respectively, for all tested substrates, was developed. Overall, the advantages of this newly developed method include operational simplicity, high stability, easy recyclability, cost-effectiveness of the catalyst, and good functional group compatibility for the synthesis ofN-methylation products as well as the industrially applicable tandem synthesis process.
Liu, Jianguo,Ma, Longlong,Song, Yanpei,Zhang, Mingyue,Zhuang, Xiuzheng
supporting information
p. 4604 - 4617
(2021/06/30)

Visible-light-promoted radical cross-coupling of: Para-quinone methides with N-substituted anilines: An efficient approach to 2,2-diarylethylamines
An efficient protocol to access 2,2-diarylethylamines via visible-light-promoted radical reactions of para-quinone methides (p-QMs) with N-alkyl anilines has been disclosed. These reactions feature metal-free, redox-neutral, and mild reaction conditions with wide functional group compatibility.
Wu, Qiao-Lei,Guo, Jing,Huang, Gong-Bin,Chan, Albert S. C.,Weng, Jiang,Lu, Gui
supporting information
p. 860 - 864
(2020/02/15)

Iridium-Catalysed Reductive Deoxygenation of Ketones with Formic Acid as Traceless Hydride Donor
An iridium-catalysed deoxygenation of ketones and aldehydes is achieved, with formic acid as hydride donor and water as co-solvent. At low catalyst loading, a number of 4-(N,N-disubstituted amino) aryl ketones are readily deoxygenated in excellent yields and chemoselectivity. Numerous functional groups, especially phenolic and alcoholic hydroxyls, secondary amine, carboxylic acid, and alkyl chloride, are well tolerable. Geminally dideuterated alkanes are obtained with up to 90% D incorporation, when DCO2D and D2O are used in place of their hydrogenative counterparts. The activating 4-(N,N-disubstituted amino)aryl groups have been demonstrated to undergo a variety of useful transformations. The deoxygenative deuterations have been used to prepare a deuterated drug molecule Chlorambucil-4,4-d2. (Figure presented.).
Yang, Zhiheng,Zhu, Xueya,Yang, Shiyi,Cheng, Weiyan,Zhang, Xiaojian,Yang, Zhanhui
supporting information
p. 5496 - 5505
(2020/10/22)

Ligand-protected Au4Ru2and Au5Ru2nanoclusters: Distinct structures and implications for site-cooperation catalysis
We report two ligand-protected Au4Ru2 and Au5Ru2 nanoclusters with distinct atomic-packing modes and electronic structures, both of which act as ideal model catalysts for identifying the catalytically active sites of catalysts on the nanoclusters. Au5Ru2 exhibits superior catalytic performances to Au4Ru2 for N-methylation of N-methylaniline to N-methylformanili, which is likely due to the site-cooperation catalysis of Au5Ru2. This journal is
Sun, Yongnan,Yang, Dan,Zhang, Yuying,Hu, Weigang,Cheng, Xinglian,Liu, Xu,Chen, Mingyang,Zhu, Yan
supporting information
p. 12833 - 12836
(2020/11/02)

Triazinetriamine-derived porous organic polymer-supported copper nanoparticles (Cu-NPs@TzTa-POP): an efficient catalyst for the synthesis of: N -methylated products via CO2fixation and primary carbamates from alcohols and urea
In recent times, carbon dioxide fixation has received much attention for its potential application as an abundant C1 source and a range of important fine chemicals can be manufactured via this fixation. Here, a copper nanoparticle-decorated porous organic polymer-based (Cu-NPs@TzTa-POP) material was prepared by a simple in situ process. The catalyst was characterized by various techniques such as UV-vis spectra, FTIR spectra, HR-TEM, PXRD, N2 adsorption-desorption, TG-DTA, XPS, and AAS analysis. The synthesized heterogeneous catalyst showed excellent activity in an atmospheric carbon dioxide fixation reaction to produce N-methylated products from aromatic/heterocyclic amines in the presence of polymethyl-hydrosiloxane (PMHS) as the reducing agent at 80 °C within 12 h of the reaction. Through this catalytic N-methylation reaction, we obtained 98% yield of the product with turnover frequency ranging from 18 to 42 h-1. The catalyst is also very stable for the formation of primary carbamates from alcohols using the eco-friendly carbonylating agent, urea. Diverse alcohols (such as benzylic alcohols, phenols, heterocyclic alcohols, as well as aliphatic alcohols) showed much acceptance to this catalytic reaction and produced moderate to excellent yields of the respective carbamate products under ambient reaction conditions. Moreover, Cu-NPs@TzTa-POP is effortlessly recyclable and reusable without the extensive loss of active copper metal centres for many catalytic rounds (up to six catalytic rounds were examined).
Haque, Najirul,Biswas, Surajit,Basu, Priyanka,Haque Biswas, Imdadul,Khatun, Resmin,Khan, Aslam,Islam, Sk Manirul
supporting information
p. 15446 - 15458
(2020/10/22)

Zn(ii)@TFP-DAQ COF: An efficient mesoporous catalyst for the synthesis of: N -methylated amine and carbamate through chemical fixation of CO2
Selective N-methylation and carbamate formation reactions were demonstrated via the chemical incorporation of CO2 using a Zn-loaded TFP-DAQ COF (covalent organic framework) as an active catalyst under mild reaction conditions. The selective N-methylation and N-formylation reactions were performed by simply varying the type of solvent. The Zn(ii)@TFP-DAQ COF catalyst was characterized via different characterization techniques such as PXRD, FTIR, UV-vis, N2 adsorption-desorption studies, FESEM and TEM. The catalyst material showed pores in the mesoporous region with a high surface area of 1117.375 m2 g-1. The as-synthesized material was applied as a cheap catalyst for the N-methylation of secondary amines and in carbamate formation reactions with high yields of the desired products up to 98.5% and 97%, respectively, with >99% selectivity. The catalyst was found to be completely heterogeneous and reusable for multiple reaction cycles.
Sarkar, Priyanka,Chowdhury, Arpita Hazra,Riyajuddin, Sk.,Biswas, Surajit,Ghosh, Kaushik,Islam, Sk. Manirul
p. 744 - 752
(2020/01/31)

Catalyst-free selective: N -formylation and N -methylation of amines using CO2 as a sustainable C1 source
We herein describe catalyst-free selective N-formylation and N-methylation of amines using CO2 as a sustainable C1 source. By tuning the reaction solvent and temperature, the selective synthesis of formamides and methylamines is achieved in good to excellent yields using sodium borohydride (NaBH4) as a sustainable reductant.
Zou, Qizhuang,Long, Guangcai,Zhao, Tianxiang,Hu, Xingbang
supporting information
p. 1134 - 1138
(2020/03/11)

Selective: N-formylation/N-methylation of amines and N-formylation of amides and carbamates with carbon dioxide and hydrosilanes: Promotion of the basic counter anions of the zinc catalyst
A catalyst composed of commercially available Zn(OAc)2 and 1,10-phenanthroline (phen) was effective in the N-formylation/N-methylation of amines using CO2 as the C1 source in the presence of hydrosilanes. An equimolar reaction of N-methylaniline with PhSiH3 under a CO2 atmosphere yielded the N-formylation product in 92% yield at 25 °C. Scale-up of the reaction using 10 mmol substrate was also successful in affording the desired product in 83% yield (1.1 g). This catalyst exhibits a high thermal stability and a turnover number (TON) of 385000 at 150 °C. In addition, the reaction of N-methylaniline in the presence of excess Ph2SiH2 produced N,N-dimethylaniline. Furthermore, our catalytic protocol was developed for the N-formylation of amides and carbamates, which have smaller pKa values and lower reactivities than the corresponding amines. The present Zn(OAc)2/phen catalyst was found to show versatility in the conversion of CO2 and amines into several functionalized organic chemicals under mild conditions. We propose that the basic counter anion (i.e., the acetate) of the catalyst activates both the Si-H and N-H bonds.
Zhang, Qiao,Lin, Xiao-Tao,Fukaya, Norihisa,Fujitani, Tadahiro,Sato, Kazuhiko,Choi, Jun-Chul
supporting information
p. 8414 - 8422
(2020/12/29)

Selective N-Methylation of N-Methylaniline with CO2 and H2 over TiO2-Supported PdZn Catalyst
A series of Pd-ZnO/TiO2, Pd/TiO2, and Pd/ZnO catalysts were synthesized and investigated for N-methylation of N-methylaniline (MA) to N,N-dimethylaniline (DMA) with CO2 and H2. A high performance was observed with a Pd-ZnO/TiO2 catalyst, with 99.9% DMA selectivity at 94% MA conversion. By contrast, both Pd/TiO2 and Pd/ZnO were less active and/or selective. The catalytic performance of Pd-ZnO/TiO2 largely depended on reduction temperature and ZnO loading. The rates for MA conversion (rateMA) and DMA production (rateDMA) increased linearly with the amount of PdZn alloy formed. The reaction was likely to take place via intermediates of N-methylformanilide (MFA) and formate. Formate was produced through the reduction of CO2 with H2 as confirmed by in situ diffuse reflectance Fourier transform infrared spectroscopy and then added to MA producing MFA, and finally, MFA was subsequently adsorbed and hydrogenated to DMA. All these steps were promoted by the PdZn alloy. The hydrogenation of MFA to DMA was much faster than the N-methylation of MA to MFA; DMA was stable, so the selectivity to DMA was almost 100% over the Pd-ZnO/TiO2 catalyst.
Arai, Masahiko,Cheng, Haiyang,Lin, Weiwei,Wu, Qifan,Zhang, Chao,Zhao, Fengyu
p. 3285 - 3296
(2020/03/10)

Photon-initiated heterogeneous redox couples for methylation of anilines under mild conditions
Methylation of anilines has drawn a lot of attention due to their valuable applications and directly using methanol as a methylation reagent is of great advantage. Photon-initiated heterogeneous catalysis of this methylation process meets the requirements of green chemistry. Herein we show that balanced redox zones within carbon nitride supported Pd nanoparticles boost the selectivity of methylation of anilines under mild conditions.
Zhang, Bing,Gao, Hua,Wang, Wei
p. 4433 - 4437
(2020/08/10)

Exhaustive Reduction of Esters Enabled by Nickel Catalysis
We report a one-step procedure to directly reduce unactivated aryl esters into their corresponding tolyl derivatives. This is achieved by an organosilane-mediated ester hydrosilylation reaction and subsequent Ni/NHC-catalyzed hydrogenolysis. The resulting conditions provide a direct and efficient alternative to multi-step procedures for this transformation that often require the use of hazardous metal hydrides. Applications in the synthesis of -CD3-containing products, derivatization of bioactive molecules, and chemoselective reduction in the presence of other C-O bonds are demonstrated.
Cook, Adam,Prakash, Sekar,Zheng, Yan-Long,Newman, Stephen G.
supporting information
p. 8109 - 8115
(2020/05/20)

Celite-Polyaniline supported palladium catalyst for chemoselective hydrogenation reactions
Polyaniline coated on particles of celite is used as support to load palladium catalyst. This heterogenized Celite?PANI?Pd system, is used as an efficient catalyst for chemoselective hydrogenation reactions. The catalyst is characterized by usual spectral, analytical techniques and studied for hydrogenation reactions at ambient conditions. The mild reaction conditions allow the control over the reactions and excellent selectivity is achieved in number of conversions. Hydrogenation of a carbon–carbon double bond was favored over other polar π-bond systems, while labile functional groups such as benzyl ether, benzyl esters, cyano, nitro and halogen remained unaffected. Primary amines were converted to N,N-dimethyl amines with formaldehyde, the double bond of coumarin was selectively hydrogenated without opening of the lactone functionality.
Patel, Heta A.,Rawat, Maitreyee,Patel, Arun L.,Bedekar, Ashutosh V.
(2019/02/26)

Para-Selective C-H Olefination of Aniline Derivatives via Pd/S,O-Ligand Catalysis
Herein we report a highly para-selective C-H olefination of aniline derivatives by a Pd/S,O-ligand-based catalyst. The reaction proceeds under mild reaction conditions with high efficiency and broad substrate scope, including mono-, di-, and trisubstituted tertiary, secondary, and primary anilines. The S,O-ligand is responsible for the dramatic improvements in substrate scope and the high para-selectivity observed. This methodology is operationally simple, scalable, and can be performed under aerobic conditions.
Naksomboon, Kananat,Poater, Jordi,Bickelhaupt, F. Matthias,Fernández-Ibá?ez, M. ángeles
supporting information
p. 6719 - 6725
(2019/05/06)

Nickel(II) Tetraphenylporphyrin as an Efficient Photocatalyst Featuring Visible Light Promoted Dual Redox Activities
Nickel(II) tetraphenylporphyrin (NiTPP) is presented as a robust, cost-effective and efficient visible light induced photoredox catalyst. The ground state electrochemical data (CV) and electronic absorption (UV-Vis) spectra reveal the excited state redox potentials for [NiTPP]*/[NiTPP].? and NiTPP].+/[NiTPP]* couples as +1.17 V and ?1.57 V vs SCE respectively. The potential values represent NiTPP as a more potent photocatalyst compare to the well-explored [Ru(bpy)3]2+. The non-precious photocatalyst exhibits excited state redox reactions in dual fashions, i. e., it is capable of undergoing both oxidative as well as reductive quenching pathways. Such versatility of a photocatalyst based on first-row transition metals is very scarce. This unique phenomenon allows one to perform diverse types of redox reactions by employing a single catalyst. Two different sets of chemical reactions have been performed to represent the synthetic utility. The catalyst showed superior efficiency in both carbon-carbon and carbon-heteroatom bond-forming reactions. Thus, we believe that NiTPP is a valuable addition to the photocatalyst library and this study will lead to more practical synthetic applications of earth-abundant-metal-based photoredox catalysts. (Figure presented.).
Mandal, Tanumoy,Das, Sanju,De Sarkar, Suman
supporting information
p. 3200 - 3209
(2019/05/16)

Synergistic catalysis of Cu+/Cu0 for efficient and selective N-methylation of nitroarenes with para-formaldehyde
In this paper, an inexpensive heterogeneous copper nanoparticles catalyst derived from CuAl-layered double hydroxide via an in situ topotactic transformation process was developed. Cu nanoparticles with uniform size were homogeneously dispersed on amorphous Al2O3 with strong metal-support interaction. Characterization results reveals that the Cu0 and Cu+ were simultaneously formed with Cu+ species as the dominant sites on the surface during the reduction process. The resultant catalyst Cu/Al2O3 demonstrates high catalytic activity, selectivity and durability for the reductive N-methylation of easily available nitroarenes in a cost-efficient, environmentally friendly and cascade manner. A broad spectrum of nitroarenes could be efficiently N-methylated to their corresponding N,N-dimethyl amines with good compatibility of various functional groups. The protocol is also applicable for the late-stage functionalization of biologically and pharmaceutically active nitro molecules. A structure-function relationship discloses that Cu0 and Cu+ sites on the surface pronouncedly boosts the reaction efficiency in a synergistic manner, in which Cu0 could facilitate H2 production and N-methylation of anilines, while Cu+ is considerably more active and participates in the overall process of the selective N-methylation of nitroarenes. Moreover, the catalyst also showed a strong stability and could be easily separated for successive reuses without an appreciable loss in activity and selectivity.
Dong, Xiaosu,Wang, Zhaozhan,Yuan, Youzhu,Yang, Yong
p. 304 - 313
(2019/07/02)

Three-Component Aminoselenation of Arynes
The three-component coupling of tertiary amines, arynes, and aryl selenium bromide or diaryl diselenide as an electrophilic selenium source allowing the synthesis of 2-selanyl aniline derivatives is reported. This aminoselenation reaction of arynes installs a C-N and C-Se bond under mild conditions, and the products are formed in moderate to good yields. This reaction is compatible with various functional groups, and the preliminary studies on the mechanism of the reaction is also provided.
Gaykar, Rahul N.,Guin, Avishek,Bhattacharjee, Subrata,Biju, Akkattu T.
supporting information
p. 9613 - 9617
(2019/11/28)

Photorearrangement of Quinoline-Protected Dialkylanilines and the Photorelease of Aniline-Containing Biological Effectors
The direct release of dialkylanilines was achieved by controlling the outcome of a photorearrangement reaction promoted by the (8-cyano-7-hydroxyquinolin-2-yl)methyl (CyHQ) photoremovable protecting group. The substrate scope was investigated to obtain structure-activity relationships and to propose a reaction mechanism. Introducing a methyl substituent at the 2-methyl position of the CyHQ core enabled the bypass of the photorearrangement and significantly improved the aniline release efficiency. We successfully applied the strategy to the photoactivation of mifepristone (RU-486), an antiprogestin drug that is also used to induce the LexPR gene expression system in zebrafish and the gene-switch regulatory system based on the pGL-VP chimeric regulator in mammals.
Deodato, Davide,Asad, Naeem,Dore, Timothy M.
p. 7342 - 7353
(2019/06/08)

Commercial Pd/C-Catalyzed N-Methylation of Nitroarenes and Amines Using Methanol as Both C1 and H2 Source
Herein, we report commercially available carbon-supported-palladium (Pd/C)-catalyzed N-methylation of nitroarenes and amines using MeOH as both a C1 and a H2 source. This transformation proceeds with high atom-economy and in an environmentally friendly way via borrowing hydrogen mechanism. A total of >30 structurally diverse N-methylamines, including bioactive compounds, were selectively synthesized with isolated yields of up to 95%. Furthermore, selective N-methylation and deuteration of nimesulide, a nonsteroidal anti-inflammatory drug, were realized through the late-stage functionalization.
Goyal, Vishakha,Gahtori, Jyoti,Narani, Anand,Gupta, Piyush,Bordoloi, Ankur,Natte, Kishore
p. 15389 - 15398
(2019/12/04)

Biomass-derived N-doped porous carbon: An efficient metal-free catalyst for methylation of amines with CO2
Developing green, efficient, and low-cost catalysts for methylation of N-H by using CO2 as the C1 resource is highly desired yet remains a significant challenge. Herein, N-doped porous carbons (NPCs) were designed, synthesized, and proved to be an excellent metal-free catalyst for CO2-participated methylation conversion. NPCs were prepared via the pyrolysis of a mixture of tannic acid and urea. Both theoretical calculation and experiment demonstrate that the N species especially pyridinic N and pyrrolic N within NPCs can work as Lewis basic sites for attacking CO2 to weaken the CO bonds and lower the molecule conversion barrier, facilitating the subsequent methylation of N-H to produce, for example, N,N-dimethylaniline. Besides, the unique porous structure can enrich CO2 and accelerate mass transfer, synergistically promoting the conversion of CO2. The optimized NPC(1/5) catalyst, integrating the porous structure and strong Lewis basicity, exhibits excellent catalytic activity for CO2-based methylation reaction under mild conditions (1 bar CO2, 75 °C). Our work, for the first time, demonstrates the feasibility of using NPCs to catalyze the methylation of amino compounds to produce N,N-dimethylamine by exploiting CO2 as the C1 resource.
Tang, Feiying,Wang, Liqiang,Liu, You-Nian
supporting information
p. 6252 - 6257
(2019/12/03)

Mn-Catalyzed Selective Double and Mono-N-Formylation and N-Methylation of Amines by using CO2
Functionalization of amines by using CO2 is of fundamental importance considering the abundance of amines and CO2. In this context, the catalytic formylation and methylation of amines represent convenient and successful protocols for selective CO2 utilization as a C1 building block. This study represents the first example of selective catalytic double N-formylation of aryl amines by using a dinuclear Mn complex in the presence of phenylsilane. This robust system also allows for selective formylation and methylation of amines under a range of conditions.
Huang, Zijun,Jiang, Xiaolin,Zhou, Shaofang,Yang, Peiju,Du, Chen-Xia,Li, Yuehui
p. 3054 - 3059
(2019/04/10)

Method for N-methylation reaction of nitro-compound
The invention discloses a method for direct N-methylation reaction by taking a nitro-compound as a raw material. The method adopts a Cu-based catalyst and polyformaldehyde and can realize the direct N-methylation reaction of the nitro-compound under mild conditions.
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Paragraph 0050-0051; 0054

(2019/01/23)

Iron-Catalyzed Selective N-Methylation and N-Formylation of Amines with CO2
We herein describe an efficient iron-catalyzed selective N-methylation and N-formylation of amines with CO2 and silane using mono-phosphine as ligand. With commercially available [CpFe(CO)2]2 as catalyst, Fe-catalyzed methylation of amines was achieved with triphenylphosphine as a ligand. Using tributylphosphine as a ligand, Fe-catalyzed formylation of amines was realized at a lower temperature. The method was successfully applied in the late-stage methylation and formylation of drug molecules containing amine moiety. (Figure presented.).
Li, Wen-Duo,Zhu, Dao-Yong,Li, Gang,Chen, Jie,Xia, Ji-Bao
supporting information
p. 5098 - 5104
(2019/11/03)

UiO-type metal-organic frameworks with NHC or metal-NHC functionalities for: N-methylation using CO2 as the carbon source
We demonstrate the first metal-organic framework (MOF) that catalyzes N-methylation of amines using 1 atm CO2 and phenylsilane under ambient conditions. Compared with its homogeneous analog, the incorporation of N-heterocyclic carbene (NHC) into the MOF provides more efficient catalysis with improved reaction kinetics, turnover numbers and recyclability. Moreover, the metalated NHC functionalized MOF achieves direct N-methylation of amines bearing carboxylate moieties, which are common building blocks in pharmaceutical chemistry.
Zhang, Xu,Jiang, Yilin,Fei, Honghan
supporting information
p. 11928 - 11931
(2019/10/11)

Eco-friendly acetylcholine-carboxylate bio-ionic liquids for controllable: N-methylation and N-formylation using ambient CO2 at low temperatures
Catalytic fixation of CO2 to produce valuable fine chemicals is of great significance to develop a green and sustainable circulation of excessive carbon in the environment. Herein, a series of non-toxic, biodegradable and recyclable acetylcholine-carboxylate bio-ionic liquids with different cations and anions were simply synthesized for producing formamides and methylamines using atmospheric CO2 as a carbon source, and phenylsilane as a hydrogen donor. The selectivity toward products was tuned by altering the reaction temperature under solvent or solvent-free conditions. N-Methylamines (ca. 96% yield) were obtained in acetonitrile at 50 °C, while N-formamides (ca. 99% yield) were attained without a solvent at 30 °C. The established bio-ionic liquid catalytic system found a wide range of applicability in substrates and possessed a high potentiality in scale-up to gram-grade production. The developed catalytic system was fairly stable, which could be easily reused without an apparent loss of reactivity, possibly due to the strong electrostatic interactions between the cation and anion. The combination of experimental and computational results explicitly elucidated the reaction mechanism: PhSiH3 activated by a bio-IL was favorable for the formation of silyl formate from hydrosilylation of CO2, followed by a reaction with an amine to give an N-formamide, while an N-methylamine was formed by further hydrosilylation of the N-formamide.
Zhao, Wenfeng,Chi, Xiaoping,Li, Hu,He, Jian,Long, Jingxuan,Xu, Yufei,Yang, Song
supporting information
p. 567 - 577
(2019/02/14)

Method for preparing important chemicals by using lignin as methyl sources
The invention relates to preparation of important chemical products by using methoxyl groups in lignin. According to a method, methyl provided by the lignin reacts with carbon monoxide and water underthe catalysis effects of catalysts to obtain acetic acid; reaction is performed with aminated compounds to obtain N-methylation products. The methoxyl groups in the lignin are used for preparing important chemical products for the first time; an important and continuous production path is provided for the preparation of various important chemical products.
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Paragraph 0097; 0098; 0120-0124

(2019/06/12)

Selective utilization of methoxy groups in lignin for: N -methylation reaction of anilines
The utilization of lignin as a feedstock to produce valuable chemicals is of great importance. However, it is a great challenge to produce pure chemicals because of the complex structure of lignin. The selective utilization of specific groups on lignin molecules offers the possibility of preparing chemicals with high selectivity, but this strategy has not attracted attention. In this work, we propose a protocol to produce methyl-substituted amines by the selective reaction of the methoxy groups of lignin and aniline compounds. It was found that LiI in the ionic liquid 1-hexyl-3-methylimidazolium tetrafluoroborate could catalyze the reaction efficiently and the selectivity to the N-methylation product could be as high as 98%. Moreover, the lignin was not depolymerized in the reaction. As it was rich in hydroxyl groups, the residual material left over after the reaction was used as an efficient co-catalyst for the cycloaddition of epoxy propane with CO2, using KI as the catalyst.
Mei, Qingqing,Shen, Xiaojun,Liu, Huizhen,Liu, Hangyu,Xiang, Junfeng,Han, Buxing
p. 1082 - 1088
(2019/02/03)

Iridium-Catalyzed Highly Efficient and Site-Selective Deoxygenation of Alcohols
An iridium-catalyzed, highly efficient, and site-selective deoxygenation of primary, secondary, and tertiary alcohols has been realized, under the assistance of a 4-(N-substituted amino)aryl directing group. Only the hydroxyl adjacent to the directing group can be deoxygenated. The deoxygenation is performed in water, with formic acid as both the promoter and hydride donor. Excellent yields and functionality tolerance, as well as high efficiency (S/C up to 1000 000, TOF up to 445 000 h-1), are obtained. The kinetic isotope effect studies show that hydride formation is the rate-determining step, and the deoxygenation follows an SN1-type pathway. The deoxygenation protocol has been demonstrated useful in the structural modification of naturally occurring ketones and steroids.
Yang, Shiyi,Tang, Weiping,Yang, Zhanhui,Xu, Jiaxi
p. 9320 - 9326
(2018/09/21)

Transformation of N, N-Dimethylaniline N-Oxides into Diverse Tetrahydroquinoline Scaffolds via Formal Povarov Reactions
A one-pot protocol for the assembly of diversely functionalized tetrahydro-, hexahydrofuro-, hexahydropyrano-, and tetrahydrobenzofuroquinolines from N,N-dimethylaniline N-oxides and various electron-rich olefins in a tandem Polonovski-Povarov sequence is reported. Following activation of the N-O bond with Boc2O, an exocyclic iminium ion is unveiled upon exposure to tin(IV) chloride. A formal inverse-electron-demand aza-Diels-Alder cyclization generates the tetrahydroquinoline core of 29 examples in up to 92% yield.
Bush, Timothy S.,Yap, Glenn P. A.,Chain, William J.
supporting information
p. 5406 - 5409
(2018/09/13)

Main-Group-Catalyzed Reductive Alkylation of Multiply Substituted Amines with Aldehydes Using H2
Given the growing demand for green and sustainable chemical processes, the catalytic reductive alkylation of amines with main-group catalysts of low toxicity and molecular hydrogen as the reductant would be an ideal method to functionalize amines. However, such a process remains challenging. Herein, a novel reductive alkylation system using H2 is presented, which proceeds via a tandem reaction that involves the B(2,6-Cl2C6H3)(p-HC6F4)2-catalyzed formation of an imine and the subsequent hydrogenation of this imine catalyzed by a frustrated Lewis pair (FLP). This reductive alkylation reaction generates H2O as the sole byproduct and directly functionalizes amines that bear a remarkably wide range of substituents including carboxyl, hydroxyl, additional amino, primary amide, and primary sulfonamide groups. The synthesis of isoindolinones and aminophthalic anhydrides has also been achieved by a one-pot process that consists of a combination of the present reductive alkylation with an intramolecular amidation and intramolecular dehydration reactions, respectively. The reaction showed a zeroth-order and a first-order dependence on the concentration of an imine intermediate and B(2,6-Cl2C6H3)(p-HC6F4)2, respectively. In addition, the reaction progress was significantly affected by the concentration of H2. These results suggest a possible mechanism in which the heterolysis of H2 is facilitated by the FLP comprising THF and B(2,6-Cl2C6H3)(p-HC6F4)2.
Hoshimoto, Yoichi,Kinoshita, Takuya,Hazra, Sunit,Ohashi, Masato,Ogoshi, Sensuke
supporting information
p. 7292 - 7300
(2018/06/01)

Tailored Cobalt-Catalysts for Reductive Alkylation of Anilines with Carboxylic Acids under Mild Conditions
The first cobalt-catalyzed hydrogenative N-methylation and alkylation of amines with readily available carboxylic acid feedstocks as alkylating agents and H2 as ideal reductant is described. Combination of tailor-made triphos ligands with cobalt(II) tetrafluoroborate significantly improved the efficiency, thus promoting the reaction under milder conditions. This novel protocol allows for a broad substrate scope with good functional group tolerance, even in the presence of reducible alkenes, esters, and amides.
Liu, Weiping,Sahoo, Basudev,Spannenberg, Anke,Junge, Kathrin,Beller, Matthias
supporting information
p. 11673 - 11677
(2018/09/10)

Diverse catalytic reactivity of a dearomatized PN3P?-nickel hydride pincer complex towards CO2 reduction
A dearomatized PN3P?-nickel hydride complex has been prepared using an oxidative addition process. The first nickel-catalyzed hydrosilylation of CO2 to methanol has been achieved, with unprecedented turnover numbers. Selective methylation and formylation of amines with CO2 were demonstrated by such a PN3P?-nickel hydride complex, highlighting its versatile functions in CO2 reduction.
Li, Huaifeng,Gon?alves, Théo P.,Zhao, Qianyi,Gong, Dirong,Lai, Zhiping,Wang, Zhixiang,Zheng, Junrong,Huang, Kuo-Wei
supporting information
p. 11395 - 11398
(2018/10/20)

Tungstate catalysis: Pressure-switched 2- and 6-electron reductive functionalization of CO2 with amines and phenylsilane
An efficient and environmentally benign tungstate catalyst for reductive functionalization of CO2 with amines and phenylsilane was developed. By simply varying the pressure, 2-electron or 6-electron reduction of CO2 was successfully achieved with simultaneous C-N bond formation, thus leading to the formation of formamides and methylamines, respectively. That is, secondary and primary amines furnished the corresponding methylamines or dimethylamines in excellent yields under atmospheric pressure of CO2, while various formamides were formed in yields ranging from 52% to 98% when increasing the CO2 pressure to 2 MPa. 1H NMR studies and control experiments demonstrate that N-formylation proceeds through the formation of silyl formate, while N-methylation proceeds through an aminal intermediate generated by 4-electron reduction of CO2.
Wang, Mei-Yan,Wang, Ning,Liu, Xiao-Fang,Qiao, Chang,He, Liang-Nian
supporting information
p. 1564 - 1570
(2018/04/12)