- Fe(III)-catalyzed Oxidative Povarov Reaction with Molecular Oxygen Oxidant
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The synthesis of tetrahydroquinoline derivatives from dimethyl anilines and enamides has been developed by Fe(III)-phenanthroline complex under aerobic condition. The oxidation of tertiary anilines involving a single electron transfer of Fe(phen)3(PF6)3 afforded the iminium ion intermediate, which reacted with electron-rich alkenes to build a six-membered N-heterocycles containing quaternary carbon center via the oxidative Povarov reaction process.
- Park, Du Yong,Hwang, Joon Young,Kang, Eun Joo
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supporting information
p. 798 - 801
(2021/04/09)
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- Photochemical Reaction of N,N-Dimethylanilines with N-Substituted Maleimides Utilizing Benzaldehyde as the Photoinitiator
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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.
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supporting information
p. 1168 - 1173
(2021/02/01)
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- Dirhodium-Catalyzed Chemo-and Site-Selective C-H Amidation of N, N-Dialkylanilines
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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)
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- CO2-tuned highly selective reduction of formamides to the corresponding methylamines
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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)
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- Visible-Light-Driven Stereoselective Annulation of Alkyl Anilines and Dibenzoylethylenes via Electron Donor-Acceptor Complexes
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A catalyst-free, stereoselective visible-light-driven annulation reaction between alkenes and N,N-substituted dialkyl anilines for the synthesis of substituted tetrahydroquinolines is presented. The reaction is driven by the photoexcitation of an electron donor-acceptor (EDA) complex, and the resulting products are obtained in good to high yields with complete diastereoselectivity. Mechanistic rationale and photochemical characterization of the EDA-complex are provided.
- Runemark, August,Zacharias, Savannah C.,Sundén, Henrik
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p. 1901 - 1910
(2021/02/05)
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- Visible light-induced N-methyl activation of unsymmetric tertiary amines
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In the presence of methylene group, selective N-methyl activation of tertiary amines has been accomplished with the aid of visible light using organic photocatalyst under air. This protocol explores numerous aliphatic and aromatic substituted tetra-hydroquinoline analogues from various tertiary amines and maleimides. Furthermore, this approach was applied to activate the methyl group of N-methyl carbazole to generate the biologically active molecule.
- Perumal, Gopi,Kandasamy, Mohanraj,Ganesan, Balaji,Govindan, Karthick,Sathya, Harsha,Hung, Min-Yuan,Chandru Senadi, Gopal,Wu, Ya-Ching,Lin, Wei-Yu
-
supporting information
(2021/01/09)
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- Visible-Light-Induced C(sp2)-C(sp3) Cross-Dehydrogenative-Coupling Reaction of N-Heterocycles with N-Alkyl- N-methylanilines under Mild Conditions
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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
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p. 11723 - 11735
(2021/09/02)
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- Alcohol promoted N -methylation of anilines with CO2/H2over a cobalt catalyst under mild conditions
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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
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p. 9147 - 9153
(2021/11/30)
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- Redox-Selective Iron Catalysis for α-Amino C-H Bond Functionalization via Aerobic Oxidation
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Single-electron oxidation and α-deprotonation of tertiary anilines using Fe(phen)3(PF6)3 afford α-aminoalkyl radicals, which can be coupled with electrophilic partners to afford various tetrahydroquinolines. Mechanistically, the Fe(phen)n 2+/3+ catalytic cycle is maintained by O2 or a TBHP oxidant, and the presence of the oxygen bound iron complex, Fe(III)-OO(H), was elucidated by electron paramagnetic resonance and electrospray ionization mass spectrometry. This redox-selective nonheme iron catalyst behaves similarly to bioinspired heme iron catalysts.
- Hwang, Joon Young,Ji, A. Young,Lee, Sang Hyeok,Kang, Eun Joo
-
supporting information
p. 16 - 21
(2019/11/11)
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- Visible-light-promoted radical cross-coupling of: Para-quinone methides with N-substituted anilines: An efficient approach to 2,2-diarylethylamines
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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
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supporting information
p. 860 - 864
(2020/02/15)
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- Continuous-Flow Amide and Ester Reductions Using Neat Borane Dimethylsulfide Complex
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Reductions of amides and esters are of critical importance in synthetic chemistry, and there are numerous protocols for executing these transformations employing traditional batch conditions. Notably, strategies based on flow chemistry, especially for amide reductions, are much less explored. Herein, a simple process was developed in which neat borane dimethylsulfide complex (BH3?DMS) was used to reduce various esters and amides under continuous-flow conditions. Taking advantage of the solvent-free nature of the commercially available borane reagent, high substrate concentrations were realized, allowing outstanding productivity and a significant reduction in E-factors. In addition, with carefully optimized short residence times, the corresponding alcohols and amines were obtained in high selectivity and high yields. The synthetic utility of the inexpensive and easily implemented flow protocol was further corroborated by multigram-scale syntheses of pharmaceutically relevant products. Owing to its beneficial features, including low solvent and reducing agent consumption, high selectivity, simplicity, and inherent scalability, the present process demonstrates fewer environmental concerns than most typical batch reductions using metal hydrides as reducing agents.
- ?tv?s, Sándor B.,Kappe, C. Oliver
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p. 1800 - 1807
(2020/02/27)
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- Transition-Metal-Free Three-Component Synthesis of Tertiary Aryl Amines from Nitro Compounds, Boronic Acids, and Trialkyl Phosphites
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The synthesis of aromatic amines is of continuous interest in chemistry. An exceptionally versatile three-component reaction that directly transforms inexpensive nitro compounds, boronic acids, and trialkyl phosphites into tertiary aromatic amines has been realized. The reaction tolerates alkyl and aryl substituents on the nitro and boronic acid moieties, as well as functionalized phosphites. No transition-metal catalysis is required. The method is orthogonal to other classical metal-catalyzed syntheses since it tolerates the presence of halogens, and also permits the synthesis of functionalized compounds such as α-amino ester derivatives. (Figure presented.).
- Roscales, Silvia,Csáky, Aurelio G.
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supporting information
p. 111 - 117
(2019/11/16)
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- C–N Cross-coupling Reactions of Amines with Aryl Halides Using Amide-Based Pincer Nickel(II) Catalyst
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Abstract: An approach to C–N cross-coupling reactions of aryl halides with amines in the presence of an amide-based pincer nickel(II) catalyst (2) is described. For 3?h reactions at 110?°C with 0.2?mol% catalyst, aryl bromides gave higher turnover numbers (TON) than the corresponding chlorides or iodides. Both primary and secondary amines could be used with the former giving higher TON. However, sterically hindered amines showed lower TON. In elucidating the mechanism of this nickel complex-catalyzed C–N cross coupling reaction it was found that the rate of reaction was unchanged in the presence of radical quenchers and a plausible Ni(I)–Ni(III) pathway is proposed. Graphic Abstract: [Figure not available: see fulltext.]Nickel pincer catalyst proved to be excellent catalyst for the C-N cross-coupling reaction with the high turnover number (TON) for 1° and 2° amines and different nonactivated aryl halides under optimum conditions.
- Albkuri, Yahya M.,RanguMagar, Ambar B.,Brandt, Andrew,Wayland, Hunter A.,Chhetri, Bijay P.,Parnell, Charlette M.,Szwedo, Peter,Parameswaran-Thankam, Anil,Ghosh, Anindya
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p. 1669 - 1678
(2019/12/27)
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- 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
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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
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supporting information
p. 15446 - 15458
(2020/10/22)
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- Zn(ii)@TFP-DAQ COF: An efficient mesoporous catalyst for the synthesis of: N -methylated amine and carbamate through chemical fixation of CO2
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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
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p. 744 - 752
(2020/01/31)
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- Ru-Catalyzed Deoxygenative Transfer Hydrogenation of Amides to Amines with Formic Acid/Triethylamine
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A ruthenium(II)-catalyzed deoxygenative transfer hydrogenation of amides to amines using HCO2H/NEt3 as the reducing agent is reported for the first time. The catalyst system consisting of [Ru(2-methylallyl)2(COD)], 1,1,1-tris(diphenylphosphinomethyl) ethane (triphos) and Bis(trifluoromethane sulfonimide) (HNTf2) performed well for deoxygenative reduction of various secondary and tertiary amides into the corresponding amines in high yields with excellent selectivities, and exhibits high tolerance toward functional groups including those that are reduction-sensitive. The choice of hydrogen source and acid co-catalyst is critical for catalysis. Mechanistic studies suggest that the reductive amination of the in situ generated alcohol and amine via borrowing hydrogen is the dominant pathway. (Figure presented.).
- Pan, Yixiao,Luo, Zhenli,Xu, Xin,Zhao, Haoqiang,Han, Jiahong,Xu, Lijin,Fan, Qinghua,Xiao, Jianliang
-
supporting information
p. 3800 - 3806
(2019/07/12)
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- B(C6F5)3-Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane
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The first B(C6F5)3-catalyzed deoxygenative reduction of amides into the corresponding amines with readily accessible and stable ammonia borane (AB) as a reducing agent under mild reaction conditions is reported. This metal-free protocol provides facile access to a wide range of structurally diverse amine products in good to excellent yields, and various functional groups including those that are reduction-sensitive were well tolerated. This new method is also applicable to chiral amide substrates without erosion of the enantiomeric purity. The role of BF3 ? OEt2 co-catalyst in this reaction is to activate the amide carbonyl group via the in situ formation of an amide-boron adduct. (Figure presented.).
- Pan, Yixiao,Luo, Zhenli,Han, Jiahong,Xu, Xin,Chen, Changjun,Zhao, Haoqiang,Xu, Lijin,Fan, Qinghua,Xiao, Jianliang
-
supporting information
p. 2301 - 2308
(2019/01/30)
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- Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines
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The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C-O bonds in amides and allows the C-N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.
- Yao, Wubing,He, Lili,Han, Deman,Zhong, Aiguo
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p. 14627 - 14635
(2019/12/02)
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- Heterogeneous Catalytic Reduction of Tertiary Amides with Hydrosilanes Using Unsupported Nanoporous Gold Catalyst
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We have demonstrated that the unsupported nanoporous gold (AuNPore) was a green and highly efficient heterogeneous catalyst for the reduction of amides to amines using hydrosilanes as reductants. A variety of tertiary amides with a broad functional groups were reduced to the corresponding tertiary amines in the presence of 2 mol% of AuNPore and PheMe2SiH or (Me2SiH)2O under mild conditions. AuNPore catalyst was recovered by simple filtration and used for twelve times without any loss of catalytic activity. The AuNPore/hydrosilane system was also successfully applied to the hydrosilative reduction of sulfoxides and N-oxides. (Figure presented.).
- Zhao, Yuhui,Zhang, Sheng,Yamamoto, Yoshinori,Bao, Ming,Jin, Tienan,Terada, Masahiro
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supporting information
p. 4817 - 4824
(2019/10/28)
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- Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines
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The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C-O bonds in amides and allows the C-N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.
- Yao, Wubing,He, Lili,Han, Deman,Zhong, Aiguo
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- A BEt3-Base catalyst for amide reduction with silane
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Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
-
-
- A BEt3-Base Catalyst for Amide Reduction with Silane
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Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
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p. 6084 - 6093
(2019/05/24)
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- Method for selective reducing reaction of tertiary aryl amide and borane
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The present invention relates to a method for a selective reducing reaction of a tertiary aryl amide and borane. A tertiary amine product is prepared by the reducing reaction of a tertiary aryl amidederivative and a cheap and easily available organoboron reagent under mild conditions under the convenient catalysis of a non-transition metal compound sodium triethylborohydride used as a catalyst for the first time. Compared with traditional methods, the method of the method generally has the advantages of wide universality of a substrate, low cost and easy availability of the catalyst, and simplicity in reaction operation. The selective reducing reaction of the tertiary aryl amide compound and the organoboron reagent under the catalysis of the transition metal catalyst is realized for the first time, and a brand new "green" reaction strategy is provided for the laboratory preparation or industrial production of tertiary arylamine products.
- -
-
Paragraph 0009-0012
(2019/10/23)
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- Iron-Catalyzed Selective N-Methylation and N-Formylation of Amines with CO2
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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)
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- Biomass-derived N-doped porous carbon: An efficient metal-free catalyst for methylation of amines with CO2
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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
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supporting information
p. 6252 - 6257
(2019/12/03)
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- Endergonic addition of N -methylamines to aromatic ketones driven by photochemical offset of the entropic cost
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Intermolecular addition reactions are generally accompanied by an entropic penalty due to the decrease of molecular numbers during the reaction, which sometimes makes the reaction endergonic. Here we demonstrate that such an endergonic reaction can be promoted with light-energy as a driving force; N-methylamines were added to aromatic ketones to produce aminoalcohols under UV-light irradiation. The reaction represents an obvious example showing that the photochemical approach is effective to offset such an entropic cost, and thereby to drive thermodynamically uphill addition reactions. Moreover the present reactions are highly expedient from the synthetic view point, being transition-metal-catalyst-free, scalable, highly atom economical, and regioselective. The product amines can be converted in one step to functional multi-arylated enamines, which are potentially valuable compounds in electronic materials.
- Iwamoto, Takahiro,Hosokawa, Atsushi,Nakamura, Masaharu
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supporting information
p. 11683 - 11686
(2019/10/02)
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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
-
supporting information
(2019/05/29)
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- Method for Preparting Alkylamines
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The present invention relates to a method for preparing alkylamines using carbon monoxide and the use of this method in the manufacturing of vitamins, pharmaceutical products, adhesives, acrylic fibres and synthetic leathers, pesticides, surfactants, detergents and fertilisers. It also relates to a method for manufacturing vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, pesticides, surfactants, detergents and fertilisers, comprising a step of preparing alkylamines by the method according to the invention. The present invention further relates to a method for preparing marked alkylamines and uses thereof.
- -
-
Paragraph 0203-0208
(2019/04/05)
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- Eco-friendly acetylcholine-carboxylate bio-ionic liquids for controllable: N-methylation and N-formylation using ambient CO2 at low temperatures
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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
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supporting information
p. 567 - 577
(2019/02/14)
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- Well-Defined Phosphine-Free Iron-Catalyzed N-Ethylation and N-Methylation of Amines with Ethanol and Methanol
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An iron(0) complex bearing a cyclopentadienone ligand catalyzed N-methylation and N-ethylation of aryl and aliphatic amines with methanol or ethanol in mild and basic conditions through a hydrogen autotransfer borrowing process is reported. A broad range of aromatic and aliphatic amines underwent mono- or dimethylation in high yields. DFT calculations suggest molecular hydrogen acts not only as a reducing agent but also as an additive to displace thermodynamic equilibria.
- Lator, Alexis,Gaillard, Sylvain,Poater, Albert,Renaud, Jean-Luc
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supporting information
p. 5985 - 5990
(2018/10/02)
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- DBU-Catalyzed Selective N-Methylation and N-Formylation of Amines with CO2 and Polymethylhydrosiloxane
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We describe herein an efficient organocatalytic system for the selective N-methylation and N-formylation of amines with carbon dioxide (CO2) as a sustainable C1 feedstock and polymethylhydrosiloxane (PMHS) as a cost-effectvie reducing reagent. High-yielding N-methylation products are obtained with low catalyst loading (1%) of DBU. Selective N-formylation of amines is achieved using the same catalytic system at a lower reaction temperature. (Figure presented.).
- Li, Gang,Chen, Jie,Zhu, Dao-Yong,Chen, Ye,Xia, Ji-Bao
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supporting information
p. 2364 - 2369
(2018/05/07)
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- Diverse catalytic reactivity of a dearomatized PN3P?-nickel hydride pincer complex towards CO2 reduction
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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
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supporting information
p. 11395 - 11398
(2018/10/20)
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- 1,4-Dioxane-Tuned Catalyst-Free Methylation of Amines by CO2 and NaBH4
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A catalyst-free reductive functionalization of CO2 with amines and NaBH4 was developed. The N-methylation of amines was carried out with CO2 as a C1 building block and 1,4-dioxane as the solvent. Notably, the six-electron reduction of CO2 to form the methyl group occurred simultaneously with formation of the C?N bond to give the N-methylated amine.
- Guo, Zhiqiang,Zhang, Bo,Wei, Xuehong,Xi, Chanjuan
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p. 2296 - 2299
(2018/07/31)
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- Tungstate catalysis: Pressure-switched 2- and 6-electron reductive functionalization of CO2 with amines and phenylsilane
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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
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supporting information
p. 1564 - 1570
(2018/04/12)
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- Copper catalysis: Ligand-controlled selective: N -methylation or N -formylation of amines with CO2 and phenylsilane
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Cupric subcarbonate (Cu2(OH)2CO3) was found to be effective for the reductive functionalization of CO2 to produce formamides and methylamines with phenylsilane as reductant. Interestingly, N-formylation and N-methylation were switched on/off by subtly choosing the ligand: DPPB (1,4-bis(diphenylphosphino)butane) promoted N-methylation whereas Ph2CyP (diphenylcyclohexylphosphine) favored for N-formylation.
- Li, Xue-Dong,Xia, Shu-Mei,Chen, Kai-Hong,Liu, Xiao-Fang,Li, Hong-Ru,He, Liang-Nian
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supporting information
p. 4853 - 4858
(2018/11/21)
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- Tailored Cobalt-Catalysts for Reductive Alkylation of Anilines with Carboxylic Acids under Mild Conditions
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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
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supporting information
p. 11673 - 11677
(2018/09/10)
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- Method for preparing formamide and N-methylamines by carrying out selective reduction on carbon dioxide and amines regulated by ligand
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The invention relates to a method for preparing formamide and N-methylamines by carrying out selective reduction on carbon dioxide and amines regulated by a ligand. According to the method, copper salt is used as a catalyst, organic amine or organic phosphorus is used as the ligand, CO2 and a hydrosilane are respectively used as a C1 resource and a reducing agent, and amines are used as a nucleophilic reagent; a reaction is carried out in an organic solvent, the consumption of the catalyst is 1-5mol%, and the consumption of the ligand is 1-20 mol%, the reaction temperature is 20-80 DEG C, theCO2 pressure is 0.1-8.0 MPa, the reaction time is 10-48h, the highest yield of the formamide is up to 98%, and the highest yield of the N-methylamine is up to 95%. The method provided by the inventionhas the advantages that the ligand is used for a regulation method for selective reduction preparation of the formamide and the N-methylamines for the first time; the catalyst is low in price, easy to obtain and simple in composition; the renewable CO2 is used as a raw material, so that the use of the traditional toxic formylation and methylation reagents is avoided; the substrate is wide in application scope and is suitable for a variety of secondary amines.
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Paragraph 0135-0142
(2019/01/14)
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- Deoxygenation of tertiary amine N-oxides under metal free condition using phenylboronic acid
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A simple and efficient method for the deoxygenation of amine N-oxides to corresponding amines is reported using the green and economical reagent phenylboronic acid. Deoxygenation of N,N-dialkylaniline N-oxides, trialkylamine N-oxides and pyridine N-oxides were achieved in good to excellent yields. The reduction susceptible functional groups such as ketone, amide, ester and nitro groups are well tolerated with phenylboronic acid during the deoxygenation process even at high temperature. In addition, an indirect method for identification and quantification of tert-amine N-oxide is demonstrated using UV–Vis spectrometry which may be useful for drug metabolism studies.
- Gupta, Surabhi,Sureshbabu, Popuri,Singh, Adesh Kumar,Sabiah, Shahulhameed,Kandasamy, Jeyakumar
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supporting information
p. 909 - 913
(2017/02/15)
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- Novel nonmetal catalytic bidirectional selective reduction method of tertiary aromatic amide
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The invention relates to a novel effective bidirectional selective environment-friendly method for hydrosilation reduction of tertiary aromatic amide and an organic silicon reagent. The method comprises the following steps: selecting a nonmetal catalytic system, and selectively preparing a secondary or tertiary organic amine compound by successively catalyzing tertiary aromatic amide and cheap PHMS or triethoxysilane under a mild condition. By adopting the method, the bidirectional selective reduction of the tertiary aromatic amide is realized by innovatively utilizing an electronic effect and steric hindrance difference of an organic silicon reagent at first time, so that a brand new strategy is provided for the reduction of amide and derivative of the amide, the defects of the traditional method that the substrate functional group is poor in compatibility, the production cost is high and the like can be overcome, and the application prospect of the amine compound prepared in industrial production or laboratory is promising.
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Paragraph 0018; 0019; 0020; 0021
(2017/10/22)
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- Carboxylate-promoted reductive functionalization of CO2 with amines and hydrosilanes under mild conditions
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Various oxygen-nucleophiles especially carboxylates, e.g. cesium/tetrabutylammonium carboxylate, were proved to be efficient and selective catalysts for reductive functionalization of CO2 with amines and hydrosilanes to methylamines. Various amines including aromatic and aliphatic, primary and secondary ones were methylated successfully in the presence of diphenylsilane as the reductant under 50 °C and an atmospheric pressure of CO2. Furthermore, a reaction pathway involving CO2 reduction to the C0 species i.e. aminal rather than the formamide as the intermediate was proposed. This protocol represents a transition metal-free and environmentally friendly option for CO2 conversion to useful chemicals via the formation of C-N bonds coupled with six-electron reduction of CO2 to the methanol level under mild conditions.
- Liu, Xiao-Fang,Qiao, Chang,Li, Xiao-Ya,He, Liang-Nian
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supporting information
p. 1726 - 1731
(2017/06/07)
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- Catalyst-free N-methylation of amines using CO2
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Recently, utilizing CO2 as a methylation reagent to construct functional chemicals has attracted significant attention. However, the conversion of CO2 is still a challenge due to its inherent inertness. In this study, we have developed a catalyst-free N-methylation of amines to prepare numerous methylamines using CO2 as a methyl source. By utilizing 2 eq. PhSiH3 as the reductant, amines could undergo N-methylation under 1 atm of CO2 in DMF at 90 °C. Aliphatic and aromatic amines were compatible, generating the desired products in up to 95% yield.
- Niu, Huiying,Lu, Lijun,Shi, Renyi,Chiang, Chien-Wei,Lei, Aiwen
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supporting information
p. 1148 - 1151
(2017/02/05)
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- Betaine Catalysis for Hierarchical Reduction of CO2 with Amines and Hydrosilane To Form Formamides, Aminals, and Methylamines
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An efficient, sustainable organocatalyst, glycine betaine, was developed for the reductive functionalization of CO2 with amines and diphenylsilane. Methylamines and formamides were obtained in high yield by tuning the CO2 pressure and reaction temperature. Based on identification of the key intermediate, that is, the aminal, an alternative mechanism for methylation involving the C0 silyl acetal and aminal is proposed. Furthermore, reducing the CO2 amount afforded aminals with high yield and selectivity. Therefore, betaine catalysis affords products with a diversified energy content that is, formamides, aminals and methylamines, by hierarchical two-, four- and six-electron reduction, respectively, of CO2 coupled with C?N bond formation.
- Liu, Xiao-Fang,Li, Xiao-Ya,Qiao, Chang,Fu, Hong-Chen,He, Liang-Nian
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supporting information
p. 7425 - 7429
(2017/06/13)
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- Copper(II)-Catalyzed Selective Reductive Methylation of Amines with Formic Acid: An Option for Indirect Utilization of CO2
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A copper-catalyzed protocol for reductive methylation of amines and imine with formic acid as a C1 source and phenylsilane as a reductant is reported for the first time, affording the corresponding methylamines in good to excellent yields under mild conditions. This protocol offers an alternative method for indirect utilization of CO2, as formic acid can be readily obtained from hydrogenation of CO2.
- Qiao, Chang,Liu, Xiao-Fang,Liu, Xi,He, Liang-Nian
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supporting information
p. 1490 - 1493
(2017/03/23)
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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 0131; 0132; 0133; 0134; 0135; 0136
(2017/08/10)
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- Preparation method of N-methylamine compound
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The invention discloses a preparation method of a N-methylamine compound. The preparation method comprises the following steps: under an inertia organic solvent or solvent-free condition and under a support-type nano-sized gold catalyst effect, a primary amine compound or a secondary amine compound is subjected to a N-methylation reaction with carbon dioxide and hydrogen to obtain the product. The preparation method takes CO2 as a methyl source, takes hydrogen as a reducing agent, and takes the support-type nano-gold as a catalyst, and has the advantages that process is simple, catalyst activity is high, reaction rate is fast, the catalyst recovery and utilization are convenient, the application scope of a substrate is wide, the production cost is low, the benifit is high, the post-treatment is simple, repeatability is good, safe performance is high, and environmental protection is achieved, and the method is adapted to industrial production.
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Paragraph 0094; 0095; 0096; 0099
(2017/08/19)
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- Versatile, mild, and selective reduction of various carbonyl groups using an electron-deficient boron catalyst
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A mild and selective new method was discovered to reduce acetanilides and other carbonyl compounds. Unlike sodium borohydride, which is selective in reducing aldehydes and ketones, this new protocol is uniquely selective in reducing acetanilides and nitriles over other carbonyl containing functional groups. Additionally, β-ketoamides were shown to be reduced at the ketone preferentially over the amide.
- Lucas, Katherine M.,Kleman, Adam F.,Sadergaski, Luke R.,Jolly, Caitlyn L.,Bollinger, Brady S.,Mackesey, Brittany L.,McGrath, Nicholas A.
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supporting information
p. 5774 - 5778
(2016/07/06)
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- Direct Acylation of C(sp3)-H Bonds Enabled by Nickel and Photoredox Catalysis
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Using nickel and photoredox catalysis, the direct functionalization of C(sp3)-H bonds of N-aryl amines by acyl electrophiles is described. The method affords a diverse range of α-amino ketones at room temperature and is amenable to late-stage coupling of complex and biologically relevant groups. C(sp3)-H activation occurs by photoredox-mediated oxidation to generate α-amino radicals which are intercepted by nickel in catalytic C(sp3)-C coupling. The merger of these two modes of catalysis leverages nickel's unique properties in alkyl cross-coupling while avoiding limitations commonly associated with transition-metal-mediated C(sp3)-H activation, including requirements for chelating directing groups and high reaction temperatures. Teamwork: The direct functionalization of C(sp3)-H bonds of N-aryl amines by acyl electrophiles is achieved, thus affording a diverse range of α-amino ketones at room temperature. C(sp3)-H activation occurs by photoredox-mediated oxidation to generate α-amino radicals which are intercepted by nickel in catalytic C(sp3)-C coupling.
- Joe, Candice L.,Doyle, Abigail G.
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supporting information
p. 4040 - 4043
(2016/03/19)
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- Esters, Including Triglycerides, and Hydrogen as Feedstocks for the Ruthenium-Catalyzed Direct N-Alkylation of Amines
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Triglycerides are used for the direct N-alkylation of amines with molecular hydrogen for the first time. A broad range of interesting and industrially relevant secondary and tertiary amines are obtained in the presence of an in situ formed Ru/Triphos complex. Notably, plant oil can be efficiently applied in this single-step process. Moreover, a variety of other methyl esters can be used as N-alkylation agents in the presence of hydrogen for the synthesis of more advanced building blocks.
- Adam, Rosa,Cabrero-Antonino, Jose R.,Junge, Kathrin,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 11049 - 11053
(2016/10/13)
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- Towards a general ruthenium-catalyzed hydrogenation of secondary and tertiary amides to amines
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A broad range of secondary and tertiary amides has been hydrogenated to the corresponding amines under mild conditions using an in situ catalyst generated by combining [Ru(acac)3], 1,1,1-tris(diphenylphosphinomethyl)ethane (Triphos) and Yb(OTf)3. The presence of the metal triflate allows to mitigate reaction conditions compared to previous reports thus improving yields and selectivities in the desired amines. The excellent isolated yields of two scale-up experiments corroborate the feasibility of the reaction protocol. Control experiments indicate that, after the initial reduction of the amide carbonyl group, the reaction proceeds through the reductive amination of the alcohol with the amine arising from collapse of the intermediate hemiaminal.
- Cabrero-Antonino, Jose R.,Alberico, Elisabetta,Junge, Kathrin,Junge, Henrik,Beller, Matthias
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p. 3432 - 3442
(2016/05/19)
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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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