- Zirconium-hydride-catalyzed site-selective hydroboration of amides for the synthesis of amines: Mechanism, scope, and application
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Developing mild and efficient catalytic methods for the selective synthesis of amines is a longstanding research objective. In this respect, catalytic deoxygenative amide reduction has proven to be promising but challenging, as this approach necessitates selective C–O bond cleavage. Herein, we report the selective hydroboration of primary, secondary, and tertiary amides at room temperature catalyzed by an earth-abundant-metal catalyst, Zr-H, for accessing diverse amines. Various readily reducible functional groups, such as esters, alkynes, and alkenes, were well tolerated. Furthermore, the methodology was extended to the synthesis of bio- and drug-derived amines. Detailed mechanistic studies revealed a reaction pathway entailing aldehyde and amido complex formation via an unusual C–N bond cleavage-reformation process, followed by C–O bond cleavage.
- Han, Bo,Jiao, Haijun,Wu, Lipeng,Zhang, Jiong
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p. 2059 - 2067
(2021/09/02)
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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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- Method for catalytically synthesizing 1-substituted pyrrolidine/piperidine derivative by using supported metal
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The invention provides a method for catalytically synthesizing a 1-substituted pyrrolidine/piperidine derivative by using a supported metal. The method comprises: carrying out a reaction with ammoniato form a pyrrolidine ring/piperidine ring by using a supported metal as a catalyst, using 1,4-butanediol/1, 5-pentanediol as a cyclization raw material and using alcohol as an N-alkylation raw material, wherein the high-selectivity synthesis of the 1-substituted pyrrolidine/piperidine derivative is achieved through the one-step reaction, the active components of the supported metal catalyst are Cu, Ni and Pd/Ru, the total loading capacity of the active components Cu and Ni is 3-15 wt% of the carrier, and the loading capacity of Pd/Ru is 0-1 wt% of the carrier. According to the invention, themethod is simple, low in cost and environmentally friendly, the conversion rate of 1,4-butanediol/1,5-pentanediol is high, the selectivity of the pyrrolidine/piperidine derivatives is high, and the method is a production route with practical application value.
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Paragraph 0016
(2020/02/20)
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- Electroactivated alkylation of amines with alcohols: Via both direct and indirect borrowing hydrogen mechanisms
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A green, efficient N-alkylation of amines with simple alcohols has been achieved in aqueous solution via an electrochemical version of the so-called "borrowing hydrogen methodology". Catalyzed by Ru on activated carbon cloth (Ru/ACC), the reaction works well with methanol, and with primary and secondary alcohols. Alkylation can be accomplished by either of two different electrocatalytic processes: (1) in an undivided cell, alcohol (present in excess) is oxidized at the Ru/ACC anode; the aldehyde or ketone product condenses with the amine; and the resulting imine is reduced at an ACC cathode, combining with protons released by the oxidation. This process consumes stoichiometric quantities of current. (2) In a membrane-divided cell, the current-activated Ru/ACC cathode effects direct C-H activation of the alcohol; the resulting carbonyl species, either free or still surface-adsorbed, condenses with amine to form imine and is reduced as in (1). These alcohol activation processes can alkylate primary and secondary aliphatic amines, as well as ammonia itself at 25-70 °C and ambient pressure.
- Appiagyei, Benjamin,Bhatia, Souful,Keeney, Gabriela L.,Dolmetsch, Troy,Jackson, James E.
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supporting information
p. 860 - 869
(2020/02/21)
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- An efficient synthesis of tertiary amines from nitriles in aprotic solvents
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Tertiary amines are utilized extensively as non-nucleophilic proton scavengers for a number of organic transformations. Herein we report the efficient syntheses of tertiary alkyl amines from their corresponding alkyl nitriles in the presence of a heterogeneous palladium catalyst and a source of dihydrogen in aprotic solvents. The reaction is atom economic, the conditions are mild, and the isolated yields are virtually quantitative. The degree of amine alkylation shows some solvent dependency; in polar protic solvents such as ethanol or methanol, the reaction affords a mixture of products with the secondary alkyl amine as the major product.
- Shares, Jonathan,Yehl, Jenna,Kowalsick, Amanda,Byers, Philip,Haaf, Michael P.
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scheme or table
p. 4426 - 4428
(2012/09/25)
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- METHOD FOR THE CATALYTIC REDUCTION OF AMIDES
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Described is a method for the catalytic reduction of an amide for the preparation of an amine at a temperature of below 200° C and a pressure of below 50 bar, the catalyst being chosen from bimetallic and trimetallic catalysts of the group consisting of ABC, AB, AC and BC, wherein: A is a metal, chosen from the group, consisting of Co, Fe, Ir, Pt, Rh and Ru, B is a metal, chosen from the group, consisting of Cr, Mo, Re and V, and, C is a metal, chosen from the group, consisting of Cu, In and Zn. Further, novel catalysts and a selection method for such catalysts is disclosed.
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Page/Page column 7-8; 9-10
(2008/06/13)
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- Theoretical and model studies on the chemoselectivity of a Grignard reagent's reaction with a combined aminonitrile-oxazolidine system
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Semi-empirical quantum chemical studies using PM3 suggest that the preferred reaction between a Grignard reagent and a combined aminonitrile-oxazolidine system involves initial formation of a Lewis acid-base complex between magnesium and the central nitrogen atom, followed by preferred reaction with the aminonitrile function; model studies confirm that this reaction proceeds by addition rather than substitution.
- Aitken, David J,Beaufort, Virginie,Chalard, Pierre,Cladière, Jean-Luc,Dufour, Monique,Pereira, Elisabeth,Théry, Vincent
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p. 5933 - 5940
(2007/10/03)
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- Study on the Effect of the Structure of the Leaving Group in the E1cb Mechanism of the Base-Promoted β-Elimination Reactions from N-alkylammonium Ions
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Studies of acid-base catalysis, H/D exchange, and solvent isotope effect on the β-elimination reactions with formation of p-nitrostyrene in acetohydroxamate/acetohydroxamic acid buffers at pH 9.05, H2O, μ = 1 M KCl, from N-alkylammonium ions with different leaving groups, such as N-methylpyrrolidine 1, N-ethylpyrrolidine 2, N-isopropylpyrrolidine 3, N-methylpiperidine 5, and N-methylazepane 6, show a change a partially reversible E1cb mechanism with 1, 2, and 4 to an irreversible E1cb mechanism with 3, 5, and 6.The change in the rate-determining step is related to the increased steric requirement of the leaving group.A steric acceleration from the carbanion intermediate to product step is proposed.
- Alunni, S.,Tijskens, P.
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p. 8371 - 8374
(2007/10/02)
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- Transition Metal-catalysed N-Alkylation of Amines by Alcohols
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Primary and secondary alcohols effect alkylation of primary and secondary amines in the presence of rhodium, iridium, and ruthenium compounds at = 100 deg C, whereby selective monoalkylation of primary amines can be achieved, and heterocyclic rings can be constructed by both inter- and intra-molecular processes.
- Grigg, R.,Mitchell, T. R. B.,Sutthivaiyakit, S.,Tongpenyai, N.
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p. 611 - 612
(2007/10/02)
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