- Deoxygenative hydroboration of primary, secondary, and tertiary amides: Catalyst-free synthesis of various substituted amines
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Transformation of relatively less reactive functional groups under catalyst-free conditions is an interesting aspect and requires a typical protocol. Herein, we report the synthesis of various primary, secondary, and tertiary amines through hydroboration of amides using pinacolborane under catalyst-free and solvent-free conditions. The deoxygenative hydroboration of primary and secondary amides proceeded with excellent conversions. The comparatively less reactive tertiary amides were also converted to the corresponding N,N-diamines in moderate yields under catalyst-free conditions, although alcohols were obtained as a minor product.
- An, Duk Keun,Jaladi, Ashok Kumar,Kim, Hyun Tae,Yi, Jaeeun
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- Method for preparing amine compound by reducing amide compound
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The invention relates to a method for preparing an amine compound by reducing an amide compound, which comprises the following steps: in a protective atmosphere, mixing the amide compound or cyclic amide, a zirconium metal catalyst and pinacol borane, carrying out amide reduction reaction at room temperature, and carrying out aftertreatment by using an ether solution of hydrogen chloride after 12-48 hours to obtain an amine hydrochloride compound. The method is simple to operate, low in cost, good in functional group tolerance and wide in substrate range.
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Paragraph 0149-0151
(2021/02/10)
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- 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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- Practical access to amines by platinum-catalyzed reduction of carboxamides with hydrosilanes: Synergy of dual Si-H groups leads to high efficiency and selectivity
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The synergetic effect of two Si-H groups leads to efficient reduction of carboxamides to amines by platinum catalysts under mild conditions. The rate of the reaction is dependent on the distance of two Si-H groups; 1,1,3,3-tetramethyldisiloxane (TMDS) and 1,2-bis(dimethylsilyl)benzene are found to be an effective reducing reagent. The reduction of amides having other reducible functional groups such as NO2, CO2R, CN, CdC, Cl, and Br moieties proceeds with these groups remaining intact, providing a reliable method for the access to functionalized amine derivatives. The platinum-catalyzed reduction of amides with polymethylhydrosiloxane (PMHS) also proceeds under mild conditions. The reaction is accompanied by automatic removal of both platinum and silicon wastes as insoluble silicone resin, and the product is obtained by simple extraction. A mechanism involving double oxidative addition of TMDS to a platinum center is discussed.
- Hanada, Shiori,Tsutsumi, Emi,Motoyama, Yukihiro,Nagashima, Hideo
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supporting information; experimental part
p. 15032 - 15040
(2010/01/29)
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- Pyrano-[2,3b]-pyridines as potassium channel antagonists
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The design and synthesis of a series of highly functionalized pyrano-[2,3b]-pyridines is described. These compounds were assayed for their ability to block the IKur channel encoded by the gene hKV1.5 in patch-clamped L-929 cells. Six of the compounds in this series showed sub-micromolar activity, the most potent being 4-(4-ethyl-benzenesulfonylamino)-3-hydroxy-2,2-dimethyl-3,4-dihydro-2H-pyrano[2,3b]-pyridine-6-carboxylic acid ethyl-phenyl-amide with an IC50 of 378 nM.
- Finlay, Heather J.,Lloyd, John,Nyman, Michael,Conder, Mary Lee,West, Tonya,Levesque, Paul,Atwal, Karnail
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p. 2714 - 2718
(2008/12/21)
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- The ruthenium-catalyzed reduction and reductive N-alkylation of secondary amides with hydrosilanes: Practical synthesis of secondary and tertiary amines by judicious choice of hydrosilanes
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(Chemical Equation Presented) A triruthenium cluster, (μ3, η2,η3,η5-acenaphthylene)Ru 3(CO)7 (1) catalyzes the reaction of secondary amides with hydrosilanes, yielding a mixture of secondary amines, tertiary amines, and silyl enamines. Production of secondary amines with complete selectivity is achieved by the use of higher concentration of the catalyst (3 mol %) and the use of bifunctional hydrosilanes such as 1,1,3,3-tetramethyldisiloxane. Acidic workup of the reaction mixture affords the corresponding ammonium salts, which can be treated with a base, providing a facile method for isolation of secondary amines with high purity. In contrast, tertiary amines are formed with high selectivity by using lower concentration of the catalyst (1 mol %) and polymeric hydrosiloxanes (PMHS) as reducing agent. Reduction with PMHS encapsulates the ruthenium catalyst and organic byproducts to the insoluble silicone resin. The two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired secondary or tertiary amine as a single product. The product contaminated with only minimal amounts of ruthenium and silicon residues. On the basis of the products and observed side products as well as NMR studies a mechanistic scenario for the reaction is also described.
- Hanada, Shiori,Ishida, Toshiki,Motoyama, Yukihiro,Nagashima, Hideo
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p. 7551 - 7559
(2008/02/12)
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- Cross Interaction Constants As a Measure of Transition State structure. Part 7. Aminolysis of Alkyl Benzenesulphonates
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Kinetic studies of the reactions of methyl and ethyl benzenesulphonates with anilines and benzylamines in methanol and acetonitrile at 65.0 deg C have been reported.The magnitudes of cross-interaction constants between substituents in the nucleophile (X) and the leaving group (Z),ρxz and βxz, were found to be greater for the ethyl series which indicates a tighter transition state for ethyl rather than methyl derivatives.This unexpected trend has been rationalized by making the assumption that the small electron-donating polar effect, of the α-methyl substituent in the ethyl compounds, requires a tighter transition-state structure in addition to the major effect of steric repulsion on the activation barrier which is present in all SN2 reactions taking place at a carbon centre.
- Lee, Ikchoon,Choi, Young Hoon,Rhyu, Keun Woo,Shim, Chang Sub
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p. 1881 - 1886
(2007/10/02)
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