- BF3·Et2O as a metal-free catalyst for direct reductive amination of aldehydes with amines using formic acid as a reductant
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A versatile metal- and base-free direct reductive amination of aldehydes with amines using formic acid as a reductant under the catalysis of inexpensive BF3·Et2O has been developed. A wide range of primary and secondary amines and diversely substituted aldehydes are compatible with this transformation, allowing facile access to various secondary and tertiary amines in high yields with wide functional group tolerance. Moreover, the method is convenient for the late-stage functionalization of bioactive compounds and preparation of commercialized drug molecules and biologically relevant N-heterocycles. The procedure has the advantages of simple operation and workup and easy scale-up, and does not require dry conditions, an inert atmosphere or a water scavenger. Mechanistic studies reveal the involvement of imine activation by BF3and hydride transfer from formic acid.
- Fan, Qing-Hua,Liu, Xintong,Luo, Zhenli,Pan, Yixiao,Xu, Lijin,Yang, Ji,Yao, Zhen,Zhang, Xin
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supporting information
p. 5205 - 5211
(2021/07/29)
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- Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3as a reductant
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Herein, we report the first example of efficient reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a catalyst and a reductant under mild conditions, affording various tertiary and secondary amines in excellent yields. A mechanistic study indicates that BH3N(C2H5)3 plays a dual function role of promoting imine and iminium formation and serving as a reductant in reductive amination. This journal is
- Zou, Qizhuang,Liu, Fei,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 8588 - 8591
(2021/09/04)
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- Highly economical and direct amination of sp3carbon using low-cost nickel pincer catalyst
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Developing more efficient routes to achieve C-N bond coupling is of great importance to industries ranging from products in pharmaceuticals and fertilizers to biomedical technologies and next-generation electroactive materials. Over the past decade, improvements in catalyst design have moved synthesis away from expensive metals to newer inexpensive C-N cross-coupling approaches via direct amine alkylation. For the first time, we report the use of an amide-based nickel pincer catalyst (1) for direct alkylation of amines via activation of sp3 C-H bonds. The reaction was accomplished using a 0.2 mol% catalyst and no additional activating agents other than the base. Upon optimization, it was determined that the ideal reaction conditions involved solvent dimethyl sulfoxide at 110 °C for 3 h. The catalyst demonstrated excellent reactivity in the formation of various imines, intramolecularly cyclized amines, and substituted amines with a turnover number (TON) as high as 183. Depending on the base used for the reaction and the starting amines, the catalyst demonstrated high selectivity towards the product formation. The exploration into the mechanism and kinetics of the reaction pathway suggested the C-H activation as the rate-limiting step, with the reaction second-order overall, holding first-order behavior towards the catalyst and toluene substrate.
- Brandt, Andrew,Rangumagar, Ambar B.,Szwedo, Peter,Wayland, Hunter A.,Parnell, Charlette M.,Munshi, Pradip,Ghosh, Anindya
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p. 1862 - 1874
(2021/01/20)
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- High-Throughput Screening of Reductive Amination Reactions Using Desorption Electrospray Ionization Mass Spectrometry
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This study describes the latest generation of a high-throughput screening system that is capable of screening thousands of organic reactions in a single day. This system combines a liquid handling robot with desorption electrospray ionization (DESI) mass spectrometry (MS) for a rapid reaction mixture preparation, accelerated synthesis, and automated MS analysis. A total of 3840 unique reductive amination reactions were screened to demonstrate the throughputs that are capable with the system. Products, byproducts, and intermediates were all monitored in full-scan mass spectra, generating a complete view of the reaction progress. Tandem mass spectrometry experiments were conducted to verify the identity of the products formed. The amine and electrophile reactivity trends represented in the data match what is expected from theory, indicating that the system accurately models the reaction performance. The DESI results correlated well with those generated using more traditional mass spectrometry techniques like liquid chromatography-mass spectrometry, validating the data generated by the system.
- Cooks, R. Graham,Ferreira, Christina R.,Li, Yangjie,Logsdon, David L.,Paschoal Sobreira, Tiago Jose,Thompson, David H.
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supporting information
p. 1647 - 1657
(2020/10/26)
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- Colloidal and Nanosized Catalysts in Organic Synthesis: XXIII. Reductive Amination of Carbonyl Compounds Catalyzed by Nickel Nanoparticles in a Plug-Flow Reactor
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Reductive amination of aldehydes and ketones with primary and secondary amines under catalysis with nickel nanoparticles supported on zeolite X, MgO, or activated carbon in the gas phase or in the gas-liquid system in a plug-flow reactor proceeds at atmospheric pressure of hydrogen with the formation of secondary or tertiary amines in high yield.
- Mokhov, V. M.,Nebykov, D. N.,Paputina, A. N.,Popov, Yu. V.,Shishkin, E. V.
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p. 2333 - 2340
(2020/02/25)
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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
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supporting information
p. 6084 - 6093
(2019/05/24)
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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
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- Highly Selective Reductive Cross-Amination between Aniline or Nitroarene Derivatives and Alkylamines Catalyzed by Polysilane-Immobilized Rh/Pt Bimetallic Nanoparticles
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Reductive cross-amination between imine intermediates generated through partial hydrogenation of aniline or nitroarene derivatives and alkylamines is an ideal method for obtaining N-alkylated cyclohexylamine derivatives; however, no such transformations have hitherto been established. Here, we report a highly selective reductive cross-amination using aniline derivatives and alkylamines catalyzed by heterogeneous Rh/Pt bimetallic nanoparticles under mild conditions. The catalyst was recovered and reused for five runs, keeping high activity. In this reaction, imine intermediates generated during the course of partial hydrogenation of aniline derivatives were trapped immediately by strongly interacting primary alkylamines with the catalyst, which caused a highly selective transformation to give the desired products, while suppressing dicyclohexylamine formation.
- Suzuki, Aya,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information
p. 387 - 392
(2019/02/26)
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- N-Alkylation of amines with phenols over highly active heterogeneous palladium hydride catalysts
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Phenols are directly converted to secondary amines in considerable yield via hydrogenation and amination tandem reaction over Al2O3 supported palladium hydride (PdHx) bi-functional catalyst. Note that this system proceeds efficiently with mild conditions under H2 atmosphere, which was difficult to achieve in previous reports. The catalyst and the mechanism of reaction are both studied. Furthermore, various secondary amines can be formed in good yields under this conversion system.
- Yan, Long,Liu, Xin-Xin,Fu, Yao
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p. 109702 - 109705
(2016/11/30)
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- Reductive amination using a combination of CaH2 and noble metal
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Amines were prepared by a reductive amination reaction in the presence of calcium hydride and Pt/C. The in situ formation of water seems to be the key to activate CaH2 to reduce the intermediate imine.
- Guyon, Carole,Da Silva, Eric,Lafon, Romain,Mtay, Estelle,Lemaire, Marc
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p. 2292 - 2298
(2015/02/05)
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- Selective alkylation of amines with alcohols by Cp*- iridium(III) half-sandwich complexes
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[Cp*Ir(Pro)Cl] (Pro = prolinato) was identified among a series of Cp*-iridium half-sandwich complexes as a highly reactive and selective catalyst for the alkylation of amines with alcohols. It is active under mild conditions in either toluene or water without the need for base or other additives, tolerates a wide range of alcohols and amines, and gives secondary amines in good to excellent isolated yields.
- Wetzel, Alexander,Woeckel, Simone,Schelwies, Mathias,Brinks, Marion K.,Rominger, Frank,Hofmann, Peter,Limbach, Michael
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supporting information
p. 266 - 269
(2013/03/14)
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- Convenient direct reductive amination of carbonyl compounds in a completely aqueous media
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We report hereby a particularly efficient synthesis of secondary, and tertiary amines respectively, through a direct reductive amination process carried for the first time in a completely aqueous media.
- Simion, Cristian,Simion, Alina M.,Arimura, Takashi,Miyazawa, Akira,Tashiro, Masashi
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scheme or table
p. 388 - 391
(2011/04/12)
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- Reductive amination agents: comparison of Na(CN)BH3 and Si-CBH
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Reductive amination is a chemical reaction commonly employed by organic chemists in academics and the pharmaceutical industry. In this reaction a carbonyl group is converted to an amine via an imine intermediate, the formation of which is rate limiting. A major reagent necessary for the completion of this reaction is a hydride source, commonly sodium cyanoborohydride (Na(CN)BH3). The objective of this research was to compare the efficacy of Na(CN)BH3 with silica-bound cyanoborohydride (Si-CBH) as hydride sources in reductive amination reactions. Work has shown that reactions employing Si-CBH as a hydride source showed significant improvement, exhibiting an average percent conversion 25% greater than reactions using Na(CN)BH3.
- Grenga, Paolo N.,Sumbler, Brittany L.,Beland, Fran?ois,Priefer, Ronny
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scheme or table
p. 6658 - 6660
(2010/03/03)
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- Direct reductive amination of carbonyl compounds using bis(triphenylphosphine) copper(I) tetrahydroborate
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A direct reductive amination protocol for aldehydes/ketones using bis(triphenylphosphine) copper(I) tetrahydroborate as a novel reducing agent in the presence of sulfamic acid has been developed. The reagent chemoselectively reduces the imine moiety and does not affect other reducible functionalities such as chloro, nitro, cyano and methoxy.
- Bhanushali, Mayur J.,Nandurkar, Nitin S.,Bhor, Malhari D.,Bhanage, Bhalchandra M.
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p. 1273 - 1276
(2007/10/03)
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- Erbium(III) triflate: A valuable catalyst for the synthesis of aldimines, ketimines, and enaminones
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Aldimines, ketimines, and enaminones can be obtained under erbium(III) inflate catalysis. The reaction mechanism is that typical of imine synthesis. The role of the catalyst is demonstrated for the synthesis of aromatic imines. In contrast to CeCl3/NaI addition to unsaturated aldehydes, which results in Michael addition, no Michael adduct was observed under erbium(III) triflate catalysis. Georg Thieme Verlag Stuttgart.
- Dalpozzo, Renato,De Nino, Antonio,Nardi, Monica,Russo, Beatrice,Procopio, Antonio
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p. 1127 - 1132
(2007/10/03)
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- A novel ruthenium-catalyzed amination of primary and secondary alcohols
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An improved method for the N-alkylation of primary amines with primary and secondary alcohols has been developed. Novel, effective catalyst systems, for example, Ru3(CO)12 combined with tri-o-tolylphosphine or n-butyl-di-1-adamantylphosphine, allow for aminations in a good yield under comparatively mild conditions.
- Tillack, Annegret,Hollmann, Dirk,Michalik, Dirk,Beller, Matthias
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p. 8881 - 8885
(2007/10/03)
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- The use of a continuous flow-reactor employing a mixed hydrogen-liquid flow stream for the efficient reduction of imines to amines
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Imines have been reduced to amines in high yield, and with excellent chemoselectivity, by catalytic hydrogenation in a continuous flow-reactor, utilising an electrochemically-generated hydrogen source to produce a mixed hydrogen-liquid flow stream. The Royal Society of Chemistry 2005.
- Saaby, Steen,Knudsen, Kristian Rahbek,Ladlow, Mark,Ley, Steven V.
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p. 2909 - 2911
(2007/10/03)
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- Borohydride exchange resin, a new reducing agent for reductive amination
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Borohydride Exchange Resin is a useful, convenient reducing agent for the reductive amination of aldehydes and ketones in alcoholic solvent.
- Yoon,Kim,Son,Choi
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p. 1595 - 1599
(2007/10/02)
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- Arene chromium tricarbonyl catalyzed reactions in organic synthesis
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Arene chromium tricarbonyl complexes have been widely used in synthetic organic chemistry. In this article, catalytic activities of these complexes in hydrogenation and isomerization are discussed. Furthermore, their application to the syntheses of biologically significant compounds such as prostaglandins, sex pheromones and antitumor antibiotics is also reviewed.
- Sodeoka,Shibasaki
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p. 643 - 658
(2007/10/02)
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- Polycyclic amines and intermediates therefor
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This invention relates to a new method for the preparation of amines containing alkylene groups by using cyclic alkylene sulphuric esters, and novel intermediates for use in the method. The new method is useful for preparation of i.a. pharmaceuticals. The novel intermediates are useful i.a. as surfactants.
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