- Furan-based acetylating agent for the chemical modification of proteins
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We have synthesized a furan-based acetylating agent, 2,5-bisacetoxymethylfuran (BAMF) from carbohydrate derived 5-hydroxymethylfurfural (HMF) and studied its acetylation activity with amines and cytochrome c. The results show that BAMF can modify proteins in biological conditions without affecting their structure and function. The modification of cytochrome c with BAMF occurred through the reduction of heme center, but there was no change in the coordination property of iron and the tertiary structure of cytochrome c. Further analysis using MALDI-TOF-MS spectrometer suggests that BAMF selectively targeted lysine amino acid of cytochrome c under our experimental conditions. Kinetics study revealed that the modification of cytochrome c with BAMF took place at faster rates than aspirin.
- De, Sudipta,Kumar, Tarun,Bohre, Ashish,Singh, Laishram R.,Saha, Basudeb
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- Ruthenium-supported catalysts for the stereoselective hydrogenation of paracetamol to 4-trans-acetamidocyclohexanol: Effect of support, metal precursor, and solvent
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The influence of the support, the metal precursor, and the solvent on the selective hydrogenation of paracetamol (4-acetamidophenol) was studied over supported ruthenium catalysts. The catalysts supported on the oxidic supports Al2O3 and SiO2 gave the best results in terms of activity, selectivity for the acetamidocyclohexanols (99%), and stereoselectivity for the trans isomer (53 and 46%, respectively). Carbon-supported catalysts produced larger amounts of secondary compounds, mainly N-cyclohexylacetamide, which was derived from the hydrogenolysis reaction of the OH group. The use of a chloride precursor resulted in the enhancement of the formation of N-cyclohexylacetamide and partially hydrogenated products; the stereoselectivity also increased. Moreover, because of the acidity caused by residual Cl, condensation led to oligomers of paracetamol. In spite of the decrease in the selectivity for cyclohexanol derivatives when the more polar solvent ethanol was used instead of isopropanol or tetrahydrofuran the stereoselectivity for the trans isomer increased from 30 to 38%. The results confirm that the factors studied affect the mode of adsorption of the molecule of paracetamol on the catalyst in different ways. These effects determine the product distribution and the selectivity of the reaction.
- Bachiller-Baeza,Guerrero-Ruiz,Rodriguez-Ramos
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- Colloid and nano-sized catalysts in organic synthesis: X. Synthesis of carboxamides by direct amidation of carboxylic acids and transamidation catalyzed by colloid copper
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Abstract It was found that in the presence of colloid copper the direct amidation of some carboxylic acids with primary and secondary amines in benzene with azeotropic distillation of water became possible. The catalyst was proven to be suitable also for transamidation reaction of a number of carboxylic acid amides under mild conditions in solvent-free conditions.
- Mokhov,Popov, Yu. V.,Budko
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- Amidomercuration; a New and Regiospecific Addition of Amides to Olefins
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The reaction of olefins with anhydrous mercury(II) nitrate in the presence of primary amides leads, after in situ alkaline sodium borohydride reduction, to the corresponding N-substituted amides; this procedure provides a new, convenient method for the Markovnikov amidation of carbon-carbon double bonds.
- Barluenga, Jose,Jimenez, Carmen,Najera, Carmen,Yus, Miguel
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- A Study on the Activation of Carboxylic Acids by Means of 2-Chloro-4,6-dimethoxy-1,3,5-triazine and 2-Chloro-4,6-diphenoxy-1,3,5-triazine
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Activation of carboxylic function by means of 2-chloro-4,6-disubstituted-1,3,5-triazines 1 and 2 leading to triazine esters was found to be a multistep process with participation of quarternary triazinylammonium salts 3-6 as the intermediates, with the rate of reaction strongly dependent on the structure of the tertiary amine. The studies on alkylation of tertiary amines with CDMT revealed the two-step process AN + DN, and zwitterionic addition product 9 was identified by 1H NMR spectroscopy. Semiempirical modeling of the reaction as well as measured nitrogen and chlorine isotope effects also support this mechanism.
- Kaminski,Paneth,Rudzinski
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- Titanocene-Catalyzed Radical Opening of N-Acylated Aziridines
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Aziridines activated by N-acylation are opened to the higher substituted radical through electron transfer from titanocene(III) complexes in a novel catalytic reaction. This reaction is applicable in conjugate additions, reductions, and cyclizations and suited for the construction of quaternary carbon centers. The concerted mechanism of the ring opening is indicated by DFT calculations.
- Zhang, Yong-Qiang,Vogelsang, Elisabeth,Qu, Zheng-Wang,Grimme, Stefan,Gans?uer, Andreas
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- AN IMPROVED MODIFICATION OF RITTER REACTION
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The reaction of alcohols 1 with trifluoromethane sulfonic anhydride (Tf2O) in dichloromethane in presence of a 2:1 excess of nitriles 3 affords the corresponding amides 5 in good yields.
- Martinez, A. Garcia,Alvarez, A. Martinez,Vilar, E. Teso,Fraile, A. Garcia,Hanack, M.,Subramanian, L. R.
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- Decarboxylative Ritter-Type Amination by Cooperative Iodine (I/III)─Boron Lewis Acid Catalysis
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Recent years have witnessed important progress in synthetic strategies exploiting the reactivity of carbocations via photochemical or electrochemical methods. Yet, most of the developed methods are limited in their scope to certain stabilized positions in molecules. Herein, we report a metal-free system based on the iodine (I/III) catalytic manifold, which gives access to carbenium ion intermediates also on electronically disfavored benzylic positions. The unusually high reactivity of the system stems from a complexation of iodine (III) intermediates with BF3. The synthetic utility of our decarboxylative Ritter-type amination protocol has been demonstrated by the functionalization of benzylic as well as aliphatic carboxylic acids, including late-stage modification of different pharmaceutical molecules. Notably, the amination of ketoprofen was performed on a gram scale. Detailed mechanistic investigations by kinetic analysis and control experiments suggest two mechanistic pathways.
- Narobe, Rok,Murugesan, Kathiravan,Schmid, Simon,K?nig, Burkhard
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p. 809 - 817
(2022/01/15)
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- A Metal-Free, Photocatalytic Method for Aerobic Alkane Iodination
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Halogenation is an important alkane functionalization strategy, but O2 is widely considered the most desirable terminal oxidant. Here, the aerobic iodination of alkanes, including methane, was performed using catalytic [nBu4N]Cl and light irradiation (390 nm). Up to 10 turnovers of CH3I were obtained from CH4 and air, using a stop-flow microtubing system. Mechanistic studies using cyclohexane as the substrate revealed important details about the iodination reaction. Iodine (I2) serves multiple roles in the catalysis: (1) as the alkyl radical trap, (2) as a precursor for the light absorber, and (3) as a mediator of aerobic oxidation. The alkane activation is attributed to Cl? derived from photofragmentation of the electron donor-acceptor complex of I2 and Cl-. The kinetic profile of cyclohexane iodination showed that aerobic oxidation of I3- to produce I2 in CH3CN is turnover-limiting.
- Anna, Jessica M.,Goldberg, Karen I.,Hirscher, Nathanael A.,Ohri, Nidhi,Schelter, Eric J.,Yang, Qiaomu,Zhou, Jiawang
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supporting information
p. 19262 - 19267
(2021/11/30)
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- Metal-free Photocatalytic Intermolecular anti-Markovnikov Hydroamination of Unactivated Alkenes
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The development of photocatalytic intermolecular hydroamination reaction between N-aminated dihydropyridines and unactivated alkenes is reported. Metal-free co-catalysts, rhodamine 6G and thiophenol, in presence of visible light are used to initiate the process. The transformation shows a broad substrate scope, both alkenes and amidyl radical can act as coupling partners. The radical strategy provides excellent anti-Markovnikov selectivity and regioselectivity in diene substrates.
- Li, Juncheng,Wang, Ting,Zhao, Gaoyuan
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supporting information
p. 2650 - 2654
(2021/06/25)
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- Preparation method of acetamide compound
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The invention discloses a preparation method of an acetamide compound, the preparation method comprises the following steps: reacting tetracarbonyl dichloride rhodium, 1, 3-bis (diphenylphosphine) propane, tungsten carbonyl, sodium phosphate, sodium iodide, water, a nitro compound and dimethyl carbonate at 120 DEG C for 24 hours, and after the reaction is completed, performing post-treatment to obtain the acetamide compound. According to the preparation method, dimethyl carbonate serves as a C1 source and also serves as a green solvent, operation is easy, reaction starting raw materials are low in price and easy to obtain, the tolerance range of substrate functional groups is wide, and reaction efficiency is high. Various acetamide compounds can be synthesized according to actual needs, so that the practicability of the method is widened while the operation is convenient.
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Paragraph 0035-0047; 0060-0063
(2021/05/19)
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- Tropylium-promoted Ritter reactions
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The Ritter reaction used to be one of the most powerful synthetic tools to functionalize alcohols and nitriles, providing valuableN-alkyl amide products. However, this reaction has not been frequently used in modern organic synthesis due to its employment of strongly acidic and harsh reaction conditions, which often lead to complicated side reactions. Herein, we report the development of a new method using salts of the tropylium ion to promote the Ritter reaction. This method works well on a range of alcohol and nitrile substrates, giving the corresponding products in good to excellent yields. This reaction protocol is amenable to microwave and continuous flow reactors, offering an attractive opportunity for further applications in organic synthesis.
- Doan, Son H.,Hussein, Mohanad A.,Nguyen, Thanh Vinh
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supporting information
p. 8901 - 8904
(2021/09/10)
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- Preparation and catalytic evaluation of a palladium catalyst deposited over modified clinoptilolite (Pd&at;MCP) for chemoselective N-formylation and N-acylation of amines
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Novel palladium nanoparticles stabilized by clinoptilolite as a natural inexpensive zeolite prepared and used for N-formylation and N-acylation of amines at room temperature at environmentally benign reaction conditions in good to excellent yields. Pd (II) was immobilized on the surface of clinoptilolite via facile multi-step amine functionalization to obtain a sustainable, recoverable, and highly active nano-catalyst. The structural and morphological characterizations of the catalyst carried out using XRD, FT-IR, BET and TEM techniques. Moreover, the catalyst is easily recovered using simple filtration and reused for 7 consecutive runs without any loss in activity.
- Amirsoleimani, Mina,Khalilzadeh, Mohammad A.,Zareyee, Daryoush
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- Mild and Selective Rhodium-Catalyzed Transfer Hydrogenation of Functionalized Arenes
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Diboron-mediated rhodium-catalyzed transfer hydrogenation of functionalized arenes is reported. In addition to good functional group tolerance, the reaction features operational simplicity and controllable chemoselectivity. The general applicability of this procedure is demonstrated by the selective hydrogenation of a range of arenes, including functionalized benzenes, biphenyls, and polyaromatics.
- Wang, Yuhan,Chang, Zhiqian,Hu, Yan,Lin, Xiao,Dou, Xiaowei
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supporting information
p. 1910 - 1914
(2021/03/08)
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- A novel construction of acetamides from rhodium-catalyzed aminocarbonylation of DMC with nitro compounds
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Dimethyl carbonate (DMC), an environment-friendly compound prepared from CO2, shows diverse reactivities. In this communication, an efficient procedure using DMC as both a C1 building block and solvent in the aminocarbonylation reaction with nitro compounds has been developed. W(CO)6acts both a CO source and a reductant here.
- Bao, Zhi-Peng,Miao, Ren-Guan,Qi, Xinxin,Wu, Xiao-Feng
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supporting information
p. 1955 - 1958
(2021/03/02)
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- New approach for induction of alkyl moiety to aliphatic amines by NaBH(OAc)3 with carboxylic acid
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We had found the novel N-alkylation method, which utilizes carboxylic acids as alkyl sources with sodium triacetoxyborohydride [NaBH(OAc)3]. Our methodology had been revealed to have some advantages over the reported similar procedures. Through
- Tamura, Satoru,Sugawara, Aoi,Sato, Erika,Sato, Fuka,Sato, Keigo,Kawano, Tomikazu
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supporting information
(2020/04/15)
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- Copper(II)-Photocatalyzed N-H Alkylation with Alkanes
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We report a practical method for the alkylation of N-H bonds with alkanes using a photoinduced copper(II) peroxide catalytic system. Upon light irradiation, the peroxide serves as a hydrogen atom transfer reagent to activate stable C(sp3)-H bonds for the reaction with a broad range of nitrogen nucleophiles. The method enables the chemoselective alkylation of amides and is utilized for the late-stage functionalization of N-H bond containing pharmaceuticals with good to excellent yields. The mechanism of the reaction was preliminarily investigated by radical trapping experiments and spectroscopic methods.
- Donabauer, Karsten,K?nig, Burkhard,Narobe, Rok,Yakubov, Shahboz,Zheng, Yi-Wen
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p. 8582 - 8589
(2020/09/23)
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- An Electrochemical Beckmann Rearrangement: Traditional Reaction via Modern Radical Mechanism
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Abstract: Electrosynthesis as a potential means of introducing heteroatoms into the carbon framework is rarely studied. Herein, the electrochemical Beckmann rearrangement, i. e. the direct electrolysis of ketoximes to amides, is presented for the first time. Using a constant current as the driving force, the reaction can be easily carried out under neutral conditions at room temperature. Based on a series of mechanistic studies, a novel radical Beckmann rearrangement mechanism is proposed. This electrochemical Beckmann rearrangement does not follow the trans-migration rule of the classical Beckmann rearrangement.
- Tang, Li,Wang, Zhi-Lv,He, Yan-Hong,Guan, Zhi
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p. 4929 - 4936
(2020/08/21)
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- New half-sandwich (η6-p-cymene)ruthenium(II) complexes with benzothiazole hydrazone Schiff base ligand: Synthesis, structural characterization and catalysis in transamidation of carboxamide with primary amines
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Few half-sandwich (η6-p-cymene) ruthenium(II) complexes supported by benzothiazole hydrazone Schiff bases were synthesized. The new complexes possess the general formulae [Ru(η6-p-cymene)(L)Cl] (1-3) (L = salicyl((2-(benzothiazol-2-yl)hydrazono)methylphenol) (SAL-HBT), 2-((2-(benzothiazol-2-yl)hydrazono)methyl)-6 methoxyphenol) (VAN-HBT) or naphtyl-2-((2-(benzothiazol-2-yl)hydrazono)methyl phenol) (NAP-HBT). All compounds were fully studied by analytical, spectroscopic techniques (IR, NMR) and also by mass spectrometry. The solid state structure of the complex 3 reveals the coordination of p-cymene moieties with ruthenium(II) in a three-legged piano-stool geometry along with benzothiazole hydrazone Schiff base ligand in a monobasic bidentate fashion. The catalytic properties of the complexes were screened in transamidation of primary amide with amines after optimization with respect to solvent, substituents, time and catalyst loading. The results show that the complex 3 is the most efficient catalyst for the transamidation of carboxamides with amines.
- Vijayapritha, Subbarayan,Viswanathamurthi, Periasamy
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supporting information
(2020/10/18)
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- Generation of amine dehydrogenases with increased catalytic performance and substrate scope from ε-deaminating L-Lysine dehydrogenase
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Amine dehydrogenases (AmDHs) catalyse the conversion of ketones into enantiomerically pure amines at the sole expense of ammonia and hydride source. Guided by structural information from computational models, we create AmDHs that can convert pharmaceutically relevant aromatic ketones with conversions up to quantitative and perfect chemical and optical purities. These AmDHs are created from an unconventional enzyme scaffold that apparently does not operate any asymmetric transformation in its natural reaction. Additionally, the best variant (LE-AmDH-v1) displays a unique substrate-dependent switch of enantioselectivity, affording S- or R-configured amine products with up to >99.9% enantiomeric excess. These findings are explained by in silico studies. LE-AmDH-v1 is highly thermostable (Tm of 69 °C), retains almost entirely its catalytic activity upon incubation up to 50 °C for several days, and operates preferentially at 50 °C and pH 9.0. This study also demonstrates that product inhibition can be a critical factor in AmDH-catalysed reductive amination.
- Tseliou, Vasilis,Knaus, Tanja,Masman, Marcelo F.,Corrado, Maria L.,Mutti, Francesco G.
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- Hydrative syntheses of amides from alkynes catalyzed by an Au(I) complex containing pyridyl-functionalized NHC ligand
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An Au(I)-NHC complex [L1AuBr] (1) with appended pyridyl group on the ligand scaffold is synthesized and its catalytic efficacy for the direct synthesis of the amide from alkyne and sodium azide in acidic water is evaluated. Catalyst 1 readily converts a wide range of internal and terminal alkynes to the corresponding amides with low catalyst loading in TFA/DCE (2 mL, 1:1 v/v) at room temperature in short reaction time (2 h) and without the use of Ag(I) additive. A related catalyst that is devoid of the pyridyl fragment displays significantly lower activity illustrating the role of the promoter ligand for water activation. Mechanistic studies reveal an initial alkyne hydration to ketone followed by the Schmidt reaction to afford the amide.
- Singh, Kuldeep,Pal, Nilay Kumar,Guha, Chirajyoti,Bera, Jitendra K.
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- An Ammonium-Formate-Driven Trienzymatic Cascade for ω-Transaminase-Catalyzed (R)-Selective Amination
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(R)-Amination mediated by (R)-specific ω-transaminases generally requires costly d-alanine in excess to obtain the desired chiral amines in high yield. Herein, a one-pot, trienzymatic cascade comprising an (R)-specific ω-transaminase, an amine dehydrogenase, and a formate dehydrogenase was developed for the economical and eco-friendly synthesis of (R)-chiral amines. Using inexpensive ammonium formate as the sole sacrificial agent, the established cascade system enabled efficient ω-transaminase-mediated (R)-amination of various ketones, with high conversions and excellent ee (>99%); water and CO2 were the only waste products.
- Chen, Fei-Fei,Liu, Lei,Wu, Jian-Ping,Xu, Jian-He,Zhang, Yu-Hui,Zhang, Zhi-Jun,Zheng, Gao-Wei
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p. 14987 - 14993
(2019/12/02)
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- Manganese-Catalyzed Direct Conversion of Ester to Amide with Liberation of H2
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A simple and efficient Mn-catalyzed acylation of amines is achieved using both acyl and alkoxy functions of unactivated esters with the liberation of molecular hydrogen as a sole byproduct. The present protocol provides an atom-economical and sustainable route for the synthesis of amides from esters by employing an earth-abundant manganese salt and inexpensive phosphine-free tridentate ligand.
- Mondal, Akash,Subaramanian, Murugan,Nandakumar, Avanashiappan,Balaraman, Ekambaram
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supporting information
p. 3381 - 3384
(2018/06/11)
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- Pivotal role of intramolecular catalysis in the selective acetylation of alkyl amines
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Preparation of amides by the use of esters as the "acyl donor" is less explored because they are less reactive and usually more steric demanding than conventional acid halides and anhydrides. Here, we report that 3-acetoxy-2-naphthoic acid, an aspirin analogue, can be used as a mild amine acetylating agent in ethanol at 25°C. The reaction is sensitive to steric and polar effects of the attacking amine, and the rate constants can be appropriately fitted by the Pavelich-Taft correlation. Density functional theory calculations used to study all reaction steps indicate that the o-carboxy group plays a pivotal role, guiding the attacking amine and accelerating the reaction. The reaction can be conveniently used for the acylation of a variety of primary and secondary amines.
- Nishida, Elvis N.,Vitto, Ramon,Peixoto, R?mulo C.R.,Nome, Faruk,Souza, Bruno S.
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- Are Aminomethyl Thioesters Viable Intermediates in Native Chemical Ligation Type Amide Bond Forming Reactions?
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The condensation of N-mercaptomethyl amines and thioesters is a potential route to amides, via aminomethyl thioester intermediates, in a native chemical ligation type process followed by self-cleavage of the 'mercaptomethyl' auxiliary. This paper describes investigations towards the preparation of aminomethyl thioesters, and subsequent conversion into amides, from a three-component coupling of formaldehyde, a thioacid, and an amine. Our studies suggest that while such intermediates may be formed en route to amides, no advantages are offered over the direct reaction of the amine and thioacid precursors.
- Charron, Carlie L.,Cottam Jones, Jade M.,Hutton, Craig A.
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p. 697 - 701
(2018/09/11)
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- Mechanochemical Activation of the Reaction of Tetraacetylglycoluril with Some Cyclic Primary Amines. Synthesis of Acetamides
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A new mechanochemical method has been proposed for the synthesis of some acetamides containing a cyclic fragment by reaction of primary cyclic amines with tetraacetylglycoluril.
- Bakibaev,Khoang,Mamontov
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p. 668 - 669
(2018/06/11)
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- Scope and mechanism of a true organocatalytic beckmann rearrangement with a boronic acid/perfluoropinacol system under ambient conditions
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Catalytic activation of hydroxyl functionalities is of great interest for the production of pharmaceuticals and commodity chemicals. Here, 2-alkoxycarbonyl- and 2-phenoxycarbonyl-phenylboronic acid were identified as efficient catalysts for the direct and chemoselective activation of oxime N-OH bonds in the Beckmann rearrangement. This classical organic reaction provides a unique approach to prepare functionalized amide products that may be difficult to access using traditional amide coupling between carboxylic acids and amines. Using only 5 mol % of boronic acid catalyst and perfluoropinacol as an additive in a polar solvent mixture, the operationally simple protocol features mild conditions, a broad substrate scope, and a high functional group tolerance. A wide variety of diaryl, aryl-alkyl, heteroaryl-alkyl, and dialkyl oximes react under ambient conditions to afford high yields of amide products. Free alcohols, amides, carboxyesters, and many other functionalities are compatible with the reaction conditions. Investigations of the catalytic cycle revealed a novel boron-induced oxime transesterification providing an acyl oxime intermediate involved in a fully catalytic nonself-propagating Beckmann rearrangement mechanism. The acyl oxime intermediate was prepared independently and was subjected to the reaction conditions. It was found to be self-sufficient; it reacts rapidly, unimolecularly without the need for free oxime. A series of control experiments and 18O labeling studies support a true catalytic pathway involving an ionic transition structure with an active and essential role for the boronyl moiety in both steps of transesterification and rearrangement. According to 11B NMR spectroscopic studies, the additive perfluoropinacol provides a transient, electrophilic boronic ester that is thought to serve as an internal Lewis acid to activate the ortho-carboxyester and accelerate the initial, rate-limiting step of transesterification between the precatalyst and the oxime substrate.
- Mo, Xiaobin,Morgan, Timothy D. R.,Ang, Hwee Ting,Hall, Dennis G.
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supporting information
p. 5264 - 5271
(2018/04/24)
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- 3D Micropatterned All-Flexible Microfluidic Platform for Microwave-Assisted Flow Organic Synthesis
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A large-area, all-flexible, microwaveable polydimethoxysilane microfluidic reactor was fabricated by using a 3D printing system. The sacrificial microchannels were printed on polydimethoxysilane substrates by a direct ink writing method using water-soluble Pluronic F-127 ink and then encapsulated between polydimethoxysilane layers. The structure of micron-sized channels was analyzed by optical and electron microscopy techniques. The fabricated flexible microfluidic reactors were utilized for the acetylation of different amines under microwave irradiation to obtain acetamides in shorter reaction times and good yields by flow organic synthesis.
- Hur, Deniz,Say, Mehmet G.,Diltemiz, Sibel E.,Duman, Fatma,Ers?z, Arzu,Say, R?dvan
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- Copper-(II) Catalyzed N-Formylation and N-Acylation of Aromatic, Aliphatic, and Heterocyclic Amines and a Preventive Study in the C-N Cross Coupling of Amines with Aryl Halides
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A Cu-(II) catalyzed N-formylation and N-acylation of amines with moderate to excellent yields, using N, N-dimethyl formamide (DMF) and N, N-dimethyl acetamide (DMA) as a formyl and acylating sources in the presence of 1,2,4-triazole is reported. This novel, highly efficient and simple protocol shows broad substrate scope for aliphatic, aromatic, and heterocyclic amines. In addition, the conditions to prevent N-formylation and N-acylation impurities in the C?N cross coupling of amines and aryl halides are described typically when DMF and DMA are used as solvents, with various catalysts, ligands, and bases.
- Sonawane, Rahul B.,Rasal, Nishant K.,Bhange, Dattatraya S.,Jagtap, Sangeeta V.
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p. 3907 - 3913
(2018/09/12)
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- Imidazolium chloride: An efficient catalyst for transamidation of primary amines
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A highly efficient and convenient protocol of imidazolium chloride (30 mol %) catalyzed amidation of amines with moderate to excellent yields was reported. The protocol shows broad substrate scope for aromatic, aliphatic, and heterocyclic primary amines.
- Tian, Qingqiang,Gan, Zongjie,Wang, Xuetong,Li, Dan,Luo, Wen,Wang, Huajun,Dai, Zeshu,Yuan, Jianyong
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supporting information
(2018/09/10)
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- Flower-like AgNPs@m-MgO as an excellent catalyst for CO2 fixation and acylation reactions under ambient conditions
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Synthesis of fine chemicals from the chemical fixation of CO2 is one of the attractive research areas of today to utilise greenhouse gas CO2 in a greener pathway. A flower-like silver nanoparticle grafted mesoporous magnesium oxide (AgNPs@m-MgO) nanocomposite has been prepared by a facile in situ pathway. The materials are characterised by XRD, FTIR, UV-vis, TG-DTA, FESEM, HR-TEM and N2 adsorption-desorption studies. This AgNPs@m-MgO material showed a mesoporous nature with good surface area. It indicated brilliant catalytic activity for both the carboxylation of terminal alkynes by chemical fixation of CO2 (1 atm) and the acylation of various amines by utilizing acetic acid as a reagent in solvent-free conditions showing yields up to 98% and 99% of the propiolic acid and acetamide products, respectively. The reusability of this catalyst has also been verified and it showed high recycling efficiency for both the reactions together with no considerable catalyst deactivation.
- Chowdhury, Arpita Hazra,Ghosh, Swarbhanu,Islam, Sk. Manirul
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p. 14194 - 14202
(2018/08/28)
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- Polysilane-Immobilized Rh-Pt Bimetallic Nanoparticles as Powerful Arene Hydrogenation Catalysts: Synthesis, Reactions under Batch and Flow Conditions and Reaction Mechanism
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Hydrogenation of arenes is an important reaction not only for hydrogen storage and transport but also for the synthesis of functional molecules such as pharmaceuticals and biologically active compounds. Here, we describe the development of heterogeneous Rh-Pt bimetallic nanoparticle catalysts for the hydrogenation of arenes with inexpensive polysilane as support. The catalysts could be used in both batch and continuous-flow systems with high performance under mild conditions and showed wide substrate generality. In the continuous-flow system, the product could be obtained by simply passing the substrate and 1 atm H2 through a column packed with the catalyst. Remarkably, much higher catalytic performance was observed in the flow system than in the batch system, and extremely strong durability under continuous-flow conditions was demonstrated (>50 days continuous run; turnover number >3.4 × 105). Furthermore, details of the reaction mechanisms and the origin of different kinetics in batch and flow were studied, and the obtained knowledge was applied to develop completely selective arene hydrogenation of compounds containing two aromatic rings toward the synthesis of an active pharmaceutical ingredient.
- Miyamura, Hiroyuki,Suzuki, Aya,Yasukawa, Tomohiro,Kobayashi, Shu
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supporting information
p. 11325 - 11334
(2018/09/06)
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- Chemoselective N-acetylation of primary aliphatic amines promoted by pivalic or acetic acid using ethyl acetate as an acetyl donor
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The combination of pivalic or acetic acid as a promoter and EtOAc as a solvent and acetyl donor proved to be efficient for the chemoselective N-acetylation of primary aliphatic amines to afford the corresponding acetamides. We developed a simple and convenient approach, which requires mild reaction conditions. Competitive inter- and intramolecular reactions between aliphatic amines, alcohols, and aromatic amines were examined, and chemoselectivity was achieved by adjusting the conditions of the reaction.
- Yoshida, Tomoki,Kawamura, Shimpei,Nakata, Kenya
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supporting information
p. 1181 - 1184
(2017/03/02)
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- Hypervalent Iodine(III)-Mediated Decarboxylative Ritter-Type Amination Leading to the Production of α-Tertiary Amine Derivatives
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α-Tertiary amines (ATAs) are attractive structural motifs that are frequently found in biologically active molecules. Therefore, the development of an efficient method for the synthesis of ATAs represents an important research topic in the field of medicinal chemistry as well as organic chemistry. Although the Ritter reaction is a reliable approach for preparing α-tertiary amine derivatives via intermolecular amination reactions, the typical methods suffer from disadvantages such as harsh reaction conditions and the use of strong acids. Because of this, it has been of limited use in the synthesis of ATAs. We report here on the decarboxylative Ritter-type amination of carboxylic acids bearing an α-quaternary carbon center using a combination of PhI(OAc)2 and molecular iodine (I2) to produce the corresponding α-tertiary amine derivatives. This reaction proceeded at ambient temperature on the benchtop with a fluorescent light. Mechanistic investigations suggest that the reaction proceeds via the formation of an alkyl iodide and a higher oxidation state iodine(III) species as key intermediates. Similarly, a stepwise protocol for the Ritter-type amination of alcohols via the formation of oxalic acid monoalkyl esters was also achieved. The present methods represent a useful tool for the synthesis of ATAs that are difficult to prepare by conventional methods.
- Kiyokawa, Kensuke,Watanabe, Tomoki,Fra, Laura,Kojima, Takumi,Minakata, Satoshi
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p. 11711 - 11720
(2017/11/27)
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- Nickel-(II)-Catalyzed N-Formylation and N-Acylation of Amines
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A highly efficient protocol of Ni(II) metal complex, [Ni(quin)2], catalyzing N-formylation and N-acylation of amines with moderate to excellent yields, using N,N-dimethylformamide and N,N-dimethylacetamide in the presence of imidazole, is described here. The protocol shows broad substrate scope for aliphatic, aromatic, and heterocyclic amines.
- Sonawane, Rahul B.,Rasal, Nishant K.,Jagtap, Sangeeta V.
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supporting information
p. 2078 - 2081
(2017/04/28)
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- An Unconventional Reaction of 2,2-Diazido Acylacetates with Amines
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We have discovered that 2,2-diazido acylacetates, a class of compounds with essentially unknown reactivity, can be coupled to amines through a new strategy that does not involve any reagents. 2,2-Diazido acetate is the unconventional leaving group under carbon–carbon bond cleavage. This reaction leads to the construction of amide bonds, tolerates various functionalities and is performed equally well in numerous solvents under experimentally simple conditions. We also demonstrate that the isolation of the 2,2-diazido acylacetate compounds can be circumvented: Acylacetates were easily fragmented when treated with (Bu4N)N3 and iodine in the presence of an amine at room temperature. By using this method, a broad range of acylacetates with various structural motifs were directly transformed into amides.
- H?ring, Andreas P.,Biallas, Phillip,Kirsch, Stefan F.
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supporting information
p. 1526 - 1539
(2017/04/01)
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- An unexpected copper-catalyzed carbonylative acetylation of amines
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A novel copper-catalyzed carbonylative acetylation of amines has been developed. With peroxide as the oxidant as well as the methyl source with a copper catalyst under CO pressure, good yields of N-acetyl amides could be obtained. Notably, this is the first example of carbonylative acetylation.
- Li, Yahui,Wang, Changsheng,Zhu, Fengxiang,Wang, Zechao,Fran?ois Soulé, Jean,Dixneuf, Pierre H.,Wu, Xiao-Feng
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supporting information
p. 142 - 144
(2016/12/27)
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- A unified photoredox-catalysis strategy for C(sp3)-H hydroxylation and amidation using hypervalent iodine
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We report a unified photoredox-catalysis strategy for both hydroxylation and amidation of tertiary and benzylic C-H bonds. Use of hydroxyl perfluorobenziodoxole (PFBl-OH) oxidant is critical for efficient tertiary C-H functionalization, likely due to the enhanced electrophilicity of the benziodoxole radical. Benzylic methylene C-H bonds can be hydroxylated or amidated using unmodified hydroxyl benziodoxole oxidant Bl-OH under similar conditions. An ionic mechanism involving nucleophilic trapping of a carbocation intermediate by H2O or CH3CN cosolvent is presented.
- Li, Guo-Xing,Morales-Rivera, Cristian A.,Gao, Fang,Wang, Yaxin,He, Gang,Liu, Peng,Chen, Gong
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p. 7180 - 7185
(2017/10/05)
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- Eco-friendly, catalyst and solvent-free, synthesis of acetanilides and N-benzothiazole-2-yl-acetamides
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An expeditious and green synthesis of acetamides in a solvent-free simple way is described, without catalyst or additives, and in good yield by an instantaneous reaction of anilines or 2-aminothiazoles and acetic anhydride without external heating, and with simple purification. Sixteen substituted acetanilides and four N-benzothiazole-2-yl-acetamides were formed, but aliphatic amines of low molecular weight were not as effective as aromatic ones, and only cyclohexylamine and the enaminone ethyl 3-amino-2-butenoate afforded the corresponding acetamides in good yield.
- Cunha, Silvio,De Santana, Louren?o L. B.
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p. 1137 - 1144
(2017/05/01)
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- N-Acyl-N-(4-chlorophenyl)-4-nitrobenzenesulfonamides: Highly selective and efficient reagents for acylation of amines in water
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A variety of N-acyl-N-(4-chlorophenyl)-4-nitrobenzenesulfonamides (1a-e) were synthesized in one pot from 4-chloroaniline under solvent-free conditions and have been developed as chemoselective N-acylation reagents. Selective protection of primary amines in the presence of secondary amines, acylation of aliphatic amines in the presence of aryl amines, and monofunctionalization of primary-secondary diamines as well as selective N-acylation of amino alcohols using these reagents are described. All of the acylation reactions were carried out in water as a green solvent. High stability and easy preparation of these acylating reagents are other advantages of this method.
- Ebrahimi, Sara,Saiadi, Safoura,Dakhilpour, Simin,Mirsattari, Seyed Nezamoddin,Massah, Ahmad Reza
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- Efficient one-stage procedure of Beckmann ketones rearrangement in the presence of hydroxylamine
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Ketoximes formed from ketones in the presence of hydroxylamine and silica gel in formic acid undergo in situ the Beckmann rearrangement under mild conditions affording in high yields the corresponding amides. Unsymmetrical aromatic ketones, methyl aryl ketones, and methyl cyclohexyl ketone under these conditions form as a rule amides mixtures.
- Kuksenok,Shtrykova,Filimonov,Sidel'nikova
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p. 196 - 199
(2016/04/19)
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- Competitive Deprotonation and Superoxide [O2 -?] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions
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Carboxamides bearing an N-H functionality are known to undergo deprotonation under negative-ion-generating mass spectrometric conditions. Herein, we report that N-H bearing carboxamides with acidities lower than that of the hydroperoxyl radical (HO-O?) preferentially form superoxide radical-anion (O2 -?) adducts, rather than deprotonate, when they are exposed to the glow discharge of a helium-plasma ionization source. For example, the spectra of N-alkylacetamides show peaks for superoxide radical-anion (O2 -?) adducts. Conversely, more acidic amides, such as N-alkyltrifluoroacetamides, preferentially undergo deprotonation under similar experimental conditions. Upon collisional activation, the O2 -? adducts of N-alkylacetamides either lose the neutral amide or the hydroperoxyl radical (HO-O?) to generate the superoxide radical-anion (m/z 32) or the deprotonated amide [m/z (M - H)-], respectively. For somewhat acidic carboxamides, the association between the two entities is weak. Thus, upon mildest collisional activation, the adduct dissociates to eject the superoxide anion. Superoxide-adduct formation results are useful for structure determination purposes because carboxamides devoid of a N-H functionality undergo neither deprotonation nor adduct formation under HePI conditions. [Figure not available: see fulltext.]
- Hassan, Isra,Pinto, Spencer,Weisbecker, Carl,Attygalle, Athula B.
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p. 394 - 401
(2016/02/23)
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- Iron-catalyzed olefin hydrogenation at 1 bar H2 with a FeCl3-LiAlH4 catalyst
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The scope and mechanism of a practical protocol for the iron-catalyzed hydrogenation of alkenes and alkynes at 1 bar H2 pressure were studied. The catalyst is formed from cheap chemicals (5 mol% FeCl3-LiAlH4, THF). A homogeneous mechanism operates at early stages of the reaction while active nanoparticles form upon ageing of the catalyst solution. This journal is
- Gieshoff, Tim N.,Villa, Matteo,Welther, Alice,Plois, Markus,Chakraborty, Uttam,Wolf, Robert,Jacobi Von Wangelin, Axel
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p. 1408 - 1413
(2015/03/18)
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- Direct Preparation of Amides from Amine Hydrochloride Salts and Orthoesters: A Synthetic and Mechanistic Perspective
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The conversion of a wide range of primary and secondary aliphatic and a few arylamine hydrochloride salts to their corresponding acetamides with trimethyl orthoacetate is described. Mechanistic studies using NMR and gas chromatography-mass spectrometry techniques indicate these reactions proceed via an O-methylimidate intermediate that undergoes in situ demethylation by chloride, affording the corresponding acetamides. Synthetically, this reaction represents a practical, high-yielding protocol with a simple workup for the rapid conversion of amine hydrochloride salts to acetamides.
- Di Grandi, Martin J.,Bennett, Caitlin,Cagino, Kristen,Muccini, Arnold,Suraci, Corey,Saba, Shahrokh
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supporting information
p. 2601 - 2607
(2015/11/28)
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- Catalytic N-Alkylation of Amines Using Carboxylic Acids and Molecular Hydrogen
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A convenient, practical and green N-alkylation of amines has been accomplished by applying readily available carboxylic acids in the presence of molecular hydrogen. Applying an in situ formed ruthenium/triphos complex and an organic acid as cocatalyst, a broad range of alkylated secondary and tertiary amines are obtained in good to excellent yields. This novel method is also successfully applied for the synthesis of unsymmetrically substituted N-methyl/alkyl anilines through a direct three-component coupling reaction of the corresponding amines, carboxylic acids, and CO2 as a C1 source.
- Sorribes, Iván,Cabrero-Antonino, Jose R.,Vicent, Cristian,Junge, Kathrin,Beller, Matthias
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p. 13580 - 13587
(2015/11/10)
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- Generation and trapping of ketenes in flow
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Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95% conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (Ea = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.
- Henry, Cyril,Bolien, David,Ibanescu, Bogdan,Bloodworth, Sally,Harrowven, David C.,Zhang, Xunli,Craven, Andy,Sneddon, Helen F.,Whitby, Richard J.
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p. 1491 - 1499
(2015/03/04)
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- Synthesis of secondary amides from N-Substituted amidines by tandem oxidative rearrangement and isocyanate elimination
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In this work an efficient tandem process transforming N-substituted amidines into secondary amides has been described. The process involves N-acylurea formation by reaction of the substrate with bis(acyloxy)(phenyl)-λ3-iodane followed by isocyanate elimination. The periodinane reagents are obtained from the commercially available phenyl-iodine(III) diacetate [PhI(OAc)2, (PIDA)] by ligand exchange with carboxylic acids. The N-substituted amidine substrates are easily synthesized from readily available nitriles. The method is applicable for secondary amide synthesis, based on both aliphatic and (hetero)aromatic amines, including challenging amides consisting of sterically hindered acids and amines. Moreover, the protocol allows one to combine steric bulk with electron deficiency in the target amides (aniline based). Such compounds are difficult to synthesize efficiently based on classical condensation reactions involving carboxylic acids and amines. Overall, the synthetic protocol transforms a nitrile into a secondary amide in both aliphatic and (hetero)aromatic systems.
- Debnath, Pradip,Baeten, Mattijs,Lefvre, Nicolas,Van Daele, Stijn,Maes, Bert U. W.
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supporting information
p. 197 - 209
(2015/03/03)
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- An attractive route to transamidation catalysis: Facile synthesis of new o-aryloxide-N-heterocyclic carbene ruthenium(II) complexes containing trans triphenylphosphine donors
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Well-defined robust ruthenium(II) complexes 3a-d bearing o-aryloxide-N-heterocyclic carbene ligands with different wingtip substituents (3a (R = Me), 3b (R = Ph), 3c (R = iPr) and 3d (R = Mes)) in the imidazole ring were synthesized in good yields by the reaction of imidazolium proligands with metal precursor [RuHCl(CO)(PPh3)3] by transmetallation from the corresponding silver carbene complexes. All the Ru(II)-NHC complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. The molecular structure of the complex 3a was identified by means of single-crystal X-ray diffraction analysis, which revealed that the complexes possess a distorted octahedral geometry. In order to explore the catalytic potential of the synthesized complexes, all the four [Ru-NHC] complexes [3a-d] were tested as catalysts for transamidation of carboxamides with amines. Notably, the complex 3a was found to be very efficient and versatile catalyst toward transamidation of a wide range of amides with amines.
- Nirmala, Muthukumaran,Prakash, Govindan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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- Efficient conversion of acids and esters to amides and transamidation of primary amides using OSU-6
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OSU-6, an MCM-41 type hexagonal mesoporous silica with strong Bronsted acid properties, has been used to promote the high-yield conversion of carboxylic acids and esters to carboxamides as well as transamidations of primary amides in a one-pot solventless approach. A metal-free heterogeneous catalyst that promotes all of these processes has not been previously reported. OSU-6 enables these transformations to proceed in shorter times and at lower temperatures for a broad range of substrates. An added benefit is that the catalyst can be recycled and reused multiple times without significant loss of activity.
- Nammalwar, Baskar,Muddala, Nagendra Prasad,Watts, Field M.,Bunce, Richard A.
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p. 9101 - 9111
(2015/11/09)
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- Designing of thermally stable amide functionalized benzimidazolium perchlorate ionic liquid for transamidation of primary carboxamides
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In the present work, we have designed and synthesized a thermally stable catalyst based on functionalized benzimidazolium perchlorate ionic liquid and tested its efficacy towards metal free and solvent free transamidation of amides and amines. The ionic liquid comprising the perchlorate ion has shown remarkably better activity than those which contain other anions and accordingly a plausible mechanism for the catalytic activity is arrived. The developed catalytic system has shown excellent activity towards the transamidation of alicyclic and aromatic amines with acetamide, benzamide and p-nitrobenzamide under mild conditions. Furthermore, the transamidation of nicotinamide with benzylamine in presence of the ionic liquid catalyst was found to occur with very good yields and thus provides a facile route for the synthesis of pharmaceutically significant compounds. The catalyst has exhibited very good thermal stability upto 203 °C and very good recyclability upto 5 runs without significant loss in its activity.
- Muskawar, Prashant Narayan,Thenmozhi,Bhagat, Pundlik Rambhau
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p. 158 - 167
(2015/09/28)
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- Highly Selective Hydrogenation of Aromatic Ketones and Phenols Enabled by Cyclic (Amino)(alkyl)carbene Rhodium Complexes
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Air-stable Rh complexes ligated by strongly σ-donating cyclic (amino)(alkyl)carbenes (CAACs) show unique catalytic activity for the selective hydrogenation of aromatic ketones and phenols by reducing the aryl groups. The use of CAAC ligands is essential for achieving high selectivity and conversion. This method is characterized by its good compatibility with unsaturated ketones, esters, carboxylic acids, amides, and amino acids and is scalable without detriment to its efficiency.
- Wei, Yu,Rao, Bin,Cong, Xuefeng,Zeng, Xiaoming
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supporting information
p. 9250 - 9253
(2015/08/11)
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- Hydrogen Self-Sufficient Arene Reduction to Cyclohexane Derivatives Using a Combination of Platinum on Carbon and 2-Propanol
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Various arenes have been hydrogenated using platinum on carbon in a 2-propanol-aqueous mixed solvent at 100 C without the addition of flammable hydrogen gas to give the corresponding cyclohexane derivatives. 2-Propanol plays a role as an efficient hydrogen source based on the platinum on carbon-catalyzed dehydrogenation.
- Sawama, Yoshinari,Mori, Misato,Yamada, Tsuyoshi,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 3667 - 3670
(2016/01/25)
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- Facile arene hydrogenation under flow conditions catalyzed by rhodium or ruthenium on carbon
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An efficient and practical protocol for the flow hydrogenation of aromatic rings was developed. The hydrogenation of a variety of aromatic compounds, such as benzene, furan, and pyridine derivatives, could be completed within only 20 s during a single pass through a catalyst cartridge containing 10 % rhodium on carbon (Rh/C) or 10 % ruthenium on carbon (Ru/C) under neutral conditions. The protocol was successfully applied to a 10 mmol scale reaction. Furthermore, the 10 % Rh/C and 10 % Ru/C did not deteriorate during the entire study.
- Hattori, Tomohiro,Ida, Takashi,Tsubone, Aya,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 2492 - 2497
(2015/04/22)
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