- Bio-heterogeneous Cu(0)NC@PHA for n-aryl/alkylation at room temperature
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A pure cellulose was derived from waste fibre and it was chemically modified to a hydroxamic acid ligand. The poly(hydroxamic acid) was treated with an aqueous copper solution to afford the greenish stable five-membered copper complex; namely Cu(II)@PHA. Further, the Cu(II)@PHA was treated with a reducing agent hydrazine hydride to give brown colour cellulose supported copper nanocomplex (Cu(0)NC@PHA). The Cu(0)NC@PHA was characterised by ATR-FTIR, FE-SEM & EDS, TEM, ICP-OES, TGA, XRD and XPS analyses. The cellulose-based Cu(0)NC@PHA was used for the n-aryl/alkylation (Michael addition) reaction with a variety of α,β-unsaturated Michael acceptors to produce the corresponding n-aryl/alkyl products with an excellent yield at room temperature. The Cu(0)NC@PHA showed extraordinary stability and it was easily filtered out from the reaction mixture and may potentially recycled up to five times without loss of its original catalytic ability.
- Jian Fui, Choong,Lutfor Rahman, Md,Musta, Baba,Sani Sarjadi, Mohd,Sarkar, Shaheen M.,Xin Ting, Tang
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- Mn-Catalyzed Selective Double and Mono-N-Formylation and N-Methylation of Amines by using CO2
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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
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p. 3054 - 3059
(2019/04/10)
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- Air-tolerant direct reductive N-methylation of amines using formic acid via simple inorganic base catalysis
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The construction of N-methyl amine moieties is an important reaction that has found numerous applications. Development of new methylation agents that are more environmentally benign than classical agents, such as iodomethane and methyl sulfate, is still highly desirable. Herein, we report a convenient protocol for direct reductive N-methylation of amines using formic acid as the methylation agent via simple inorganic base catalysis. The present protocol operates under transition-metal-free and air-tolerant conditions. Both the catalyst, K2HPO4, and the reductant, polymethylhydrosiloxane (PMHS), are cheap and easily separable from the crude reaction product mixture. Mechanistic investigations suggest that the reaction occur through the formation of an acetal intermediate followed by the C–N bond formation.
- Huang, Yan,Deng, Wei,Lin, Bo-Lin
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supporting information
(2019/05/29)
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- Methylation method of amines
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The invention provides a methylation method of amines. The method is characterized by comprising the steps that under the protection of nitrogen or inert gas, organic amines, a reductive agent polymethyl hydrogen siloxane or diphenyl silane, a catalyst potassium phosphate and an additive 18-crown-6 are added into a reaction container, and an reaction is made with carbon dioxide as a C1 source to obtain methylated products of amines. According to the method, potassium phosphate serves as the catalyst, the carbon dioxide serves as the C1 source, polymethyl hydrogen siloxane or diphenyl silane serves as the reductive agent, and 18-crown-6 serves as the additive. Various kinds of amines are converted into the corresponding methylated products in an acetonitrile solvent or without solvents. Two waste materials including the carbon dioxide and polymethyl hydrogen siloxane (PMHS) serve as the C1 source and the reductive agent in the method respectively, phosphate serves as the catalyst, the cost is low, and the conversion efficiency is high. Thus, the method makes an important contribution to the development of green chemistry.
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Paragraph 0055; 0056; 0057; 0058; 0059; 0060
(2017/12/04)
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- Preparation method by using amine and imine nitrogen methylation and application thereof
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The invention discloses a preparation method by using amine and imine nitrogen methylation and application thereof. The preparation method comprises the following steps: A, adding an active carbon loaded platinum catalyst into a Schlenk tube, and after vacuumizing to replace argon, adding a solvent; B, under protection of argon, separately adding phenylsilane, an initial raw material and formic acid; C, stirring the whole reaction system at a certain temperature to react; and D, after reaction, adding ethyl acetate into the system to dilute, stopping the reaction by using a sodium hydroxide aqueous solution, performing extraction with ethyl acetate, separating out an organic phase, drying and filtering the organic phase, and performing rotatable evaporation to remove the solvent. Column chromatography is performed on residues by using ethyl acetate/petroleum ether mixed solvent to obtain a target product, wherein the ethyl acetate and petroleum ether are different in proportion. According to the application of the method in isotope labeled drug synthesis, the dosage of a catalyst is extremely low, the cost is quite low, and the method is suitable for large-scaled production, can be suitable for amine and imine with different substituents, and suitable for realizing methylation conveniently on nitrogen atoms in a natural product structure to prepare drug molecules.
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Paragraph 0165; 0166; 0167; 0168; 0169; 0170
(2017/08/10)
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- Selective formylation and methylation of amines using carbon dioxide and hydrosilane catalyzed by alkali-Metal carbonates
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The formylation and methylation of amines with carbon dioxide and hydrosilanes are emerging yet important types of transformations for CO2. Catalytic methods effective for both reactions with wide substrate scopes are rare because of the difficulty in controlling the selectivity. Herein, we report that simple and readily available inorganic bases alkali-metal carbonates, especially cesium carbonatecatalyze both the formylation and methylation reactions efficiently under mild conditions. The selectivity can be conveniently controlled by varying the reaction temperature and silane. A “cesium effect” on both reactions was observed by comparing the catalytic activity of various alkali-metal carbonates. Combined experimental and computational studies suggested the following reaction mechanism: (i) activation of Si?H by Cs2CO3, (ii) insertion of CO2 into Si?H, (iii) formylation of amines by silyl formate, and (iv) reduction of formamides to methylamines.
- Fang, Chi,Lu, Chunlei,Liu, Muhua,Zhu, Yiling,Fu, Yao,Lin, Bo-Lin
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p. 7876 - 7881
(2018/05/23)
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- Methylation of aromatic amines and imines using formic acid over a heterogeneous Pt/C catalyst
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We describe here a commercially available Pt/C catalyst capable of catalyzing the methylation of anilines and aromatic imines with formic acid in the presence of a hydrosilane reductant. Both primary aniline and secondary aniline can be methylated. The advantage of this newly described method includes operational simplicity, high TON, ready availability of the catalyst, and also good functional group compatibility.
- Zhu, Lei,Wang, Lian-Sheng,Li, Bojie,Li, Wei,Fu, Boqiao
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p. 6172 - 6176
(2016/08/19)
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- Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids
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A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet. and Piribedil, in a one-pot manner without using any metal catalysts.
- Fu, Ming-Chen,Shang, Rui,Cheng, Wan-Min,Fu, Yao
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supporting information
p. 9042 - 9046
(2015/08/03)
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- Benefits of a Dual Chemical and Physical Activation: Direct aza-Michael Addition of Anilines Promoted by Solvent Effect under High Pressure
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The unique combination of hexafluoroisopropanol (HFIP) employed as solvent and hyperbaric conditions (10-15 kbar) allows unprecedented 1,4-addition of poor nucleophiles, such as aromatic amines, onto sluggish (cumbersome) Michael acceptors without any promoter or workup.
- Fedotova, Alena,Crousse, Benoit,Chataigner, Isabelle,Maddaluno, Jacques,Rulev, Alexander Yu.,Legros, Julien
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supporting information
p. 10375 - 10379
(2015/11/03)
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- General catalytic methylation of amines with formic acid under mild reaction conditions
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A general catalytic protocol for the methylation of amines has been developed applying, for the first time, formic acid as the C1 building block and silanes as reducing agents. A broad range of aromatic and aliphatic, both primary and secondary, amines has been converted to the corresponding tertiary amines including [N-13C]-labelled drugs in good to excellent yields under mild conditions. Methylation made easy: A general catalytic protocol for the methylation of amines has been developed applying, for the first time, formic acid as the C1 building block and silanes as reducing agents. A broad range of aromatic and aliphatic, both primary and secondary, amines has been converted to the corresponding tertiary amines, including [N-13C]-labelled drugs, in good to excellent yields at mild conditions (see scheme; dppp=(1,3-bis(diphenylphosphino)propane)).
- Sorribes, Ivan,Junge, Kathrin,Beller, Matthias
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supporting information
p. 7879 - 7883
(2014/07/07)
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- Chemo/regioselective Aza-Michael additions of amines to conjugate alkenes catalyzed by polystyrene-supported AlCl3
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A simple and efficient procedure is presented for Aza-Michael additions of various amines with conjugate alkenes bearing electron withdrawing group catalyzed by polystyrene-supported aluminum chloride (Ps-AlCl3) without the use of any solvents. The catalyst shows high catalytic activity for both aromatic amines and aliphatic amines. Chemoselective additions of the two types of amines with conjugate alkenes are achieved. Regioselective additions of two different amino groups in one molecule proceed smoothly. Ps-AlCl 3 has better recyclability and can be reused several times without apparent loss of activity.
- Dai, Liyan,Zhang, Yi,Dou, Qianqian,Wang, Xiaozhong,Chen, Yingqi
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p. 1712 - 1716
(2013/03/13)
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- Supported cobalt complex-catalysed conjugate addition of indoles, amines and thiols to α,β-unsaturated compounds
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A highly active and reusable supported Co(ii) complex on SBA-15 shows an excellent activity and selectivity to target products in aza- and thia-Michael conjugate additions of indoles, amines and thiols to α,β-unsaturated compounds under solventless mild reaction conditions. The Co-catalyst was also highly reusable and comparably more active than related catalysts in the reaction.
- Rajabi, Fatemeh,Razavi, Sepideh,Luque, Rafael
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experimental part
p. 786 - 789
(2010/09/05)
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- Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen or hydrogen peroxide and sodium cyanide: Sp3 C-H bond activation and carbon-carbon bond formation
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Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen in the presence of sodium cyanide and acetic acid gives the corresponding α-aminonitriles, which are highly useful intermediates for organic synthesis. The reaction is the first demonstration of direct sp3 C-H bond activation α to nitrogen followed by carbon-carbon bond formation under aerobic oxidation conditions. The catalytic oxidation seems to proceed by (i) α-C-H activation of tertiary amines by the ruthenium catalyst to give an iminium ion/ruthenium hydride intermediate, (ii) reaction with molecular oxygen to give an iminium ion/ruthenium hydroperoxide, (iii) reaction with HCN to give the α-aminonitrile product, H2O2, and Ru species, (iv) generation of oxoruthenium species from the reaction of Ru species with H2O2, and (v) reaction of oxoruthenium species with tertiary amines to give α-aminonitriles. On the basis of the last two pathways, a new type of ruthenium-catalyzed oxidative cyanation of tertiary amines with H2O2 to give α-aminonitriles was established. The α-aminonitriles thus obtained can be readily converted to α-amino acids, diamines, and various nitrogen-containing heterocyclic compounds.
- Murahashi, Shun-Ichi,Nakae, Takahiro,Terai, Hiroyuki,Komiya, Naruyoshi
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scheme or table
p. 11005 - 11012
(2009/02/05)
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- A catalytic method for room-temperature Michael additions using 12-tungstophosphoric acid as a reusable catalyst in water
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12-Tungstophosphoric acid (H3PW12O40) has been found to be an efficient and recyclable catalyst in promoting room temperature Michael additions of amines and aryl thiols to α,β- unsaturated esters and acrylonitrile in water to afford the corresponding saturated amines in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Chen, Xiang,She, Jin,Shang, Zhicai,Wu, Jun,Zhang, Peizhi
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experimental part
p. 3931 - 3936
(2009/05/26)
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- Imidazolium-based polymer supported gadolinium triflate as a heterogeneous recyclable Lewis acid catalyst for Michael additions
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A heterogeneous Lewis acid catalytic system has been developed by incorporating gadolinium triflate on to poly[styrene-co-(1-((4-vinylphenyl)methyl)-3-methylimidazolium) tetrafluoroborate] (1-Gd(OTf)3), and the catalytic activity of this system has been examined for Michael additions of amines and thiols to α,β-unsaturated esters and acrylonitrile. The reactions proceed in moderate to excellent yields in the presence of catalytic system 1-Gd(OTf)3. The catalytic system could be efficiently recycled and reused.
- Alleti, Ramesh,Oh, Woon Su,Perambuduru, Meher,Ramana,Prakash Reddy
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p. 3466 - 3470
(2008/09/21)
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