- Electrochemical radical reactions of alkyl iodides: a highly efficient, clean, green alternative to tin reagents
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An electrochemical ‘redox-relay’ system has been developed which allows the generation of C-centered radicals. Intermolecular ‘tin-like’ radical reactions can subsequently be conducted under the most benign of conditions. The yields and efficiency of the processes are competitive and even superior in most cases to comparable conditions with tributyltin hydride. The use of air and electricity as the promotor (instead of a tin or other reagent) combined with the aqueous reaction media make this a clean and ‘green’ alternative to these classic C-C bond forming processes.
- Li, Diyuan,Ma, Tsz-Kan,Scott, Reuben J.,Wilden, Jonathan D.
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p. 5333 - 5338
(2020/06/04)
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- A Redox-Active Nickel Complex that Acts as an Electron Mediator in Photochemical Giese Reactions
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We report a simple protocol for the photochemical Giese addition of C(sp3)-centered radicals to a variety of electron-poor olefins. The chemistry does not require external photoredox catalysts. Instead, it harnesses the excited-state reactivity of 4-alkyl-1,4-dihydropyridines (4-alkyl-DHPs) to generate alkyl radicals. Crucial for reactivity is the use of a catalytic amount of Ni(bpy)32+ (bpy=2,2′-bipyridyl), which acts as an electron mediator to facilitate the redox processes involving fleeting and highly reactive intermediates.
- van Leeuwen, Thomas,Buzzetti, Luca,Perego, Luca Alessandro,Melchiorre, Paolo
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supporting information
p. 4953 - 4957
(2019/03/13)
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- Formal reductive addition of acetonitrile to aldehydes and ketones
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An efficient and highly productive rhodium-catalyzed method for the synthesis of nitriles employing aldehydes or ketones, methyl cyanoacetate, water and carbon monoxide as starting materials has been developed. Simple rhodium chloride without any ligands can be used. The fine tuning of the substrate can lead to the activity higher than 5000 TON.
- Muratov, Karim,Kuchuk, Ekaterina,Vellalath, Sreekumar,Afanasyev, Oleg I.,Moskovets, Alexei P.,Denisov, Gleb,Chusov, Denis
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supporting information
p. 7693 - 7701
(2018/11/02)
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- Efficient nickel-catalyzed hydrocyanation of alkenes using acetone cyanohydrin as a safer cyano source
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An active nickel catalyst prepared in situ from a Ni(II) compound, phosphine ligand, and zinc powder was found to be an efficient catalyst system for the hydrocyanation of various alkenes using acetone cyanohydrin as a safer cyano source. The combination of NiCl2·6H2O and 1,3-bis(diphenylphosphino)propane was the most efficient catalyst precursor in DMF. Under the optimized conditions, various styrenes, heterocyclic alkenes, and aliphatic alkenes were converted to their corresponding nitriles in excellent yields.
- Nemoto, Koji,Nagafuchi, Tsuyoshi,Tominaga, Ken-ichi,Sato, Kazuhiko
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p. 3199 - 3203
(2016/07/06)
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- Reductive Transformations of Carbonyl Compounds Catalyzed by Rhodium Supported on a Carbon Matrix by using Carbon Monoxide as a Deoxygenative Agent
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An efficient method for the rhodium on carbon matrix catalyzed preparation of secondary and tertiary amines, cyanoesters, and nitriles through the reductive amination/alkylation of carbonyl compounds was developed, including a convenient procedure for the tandem formal reductive addition of acetonitrile to aldehydes. The catalyst could be reused, and at least three consecutive reaction cycles were performed with comparable efficiency. The method was shown to be compatible with functional groups prone to reduction by hydrogen and complex hydrides. Beyond the matrix: An efficient method for the rhodium on carbon matrix catalyzed preparation of secondary and tertiary amines, cyanoesters, and nitriles through the reductive amination/alkylation of carbonyl compounds is developed, including a convenient procedure for the tandem formal reductive addition of acetonitrile to aldehydes. TON=turnover number.
- Yagafarov, Niyaz Z.,Usanov, Dmitry L.,Moskovets, Alexey P.,Kagramanov, Nikolai D.,Maleev, Victor I.,Chusov, Denis
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p. 2590 - 2593
(2015/09/15)
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- Chemoenzymatic synthesis of a series of 4-substituted glutamate analogues and pharmacological characterization at human glutamate transporters subtypes 1-3
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A series of nine L-2,4-s;yrc-4-alkylglutamic acid analogues (1a-i) were synthesized in high yield and high enantiomeric excess (>99% ee) from their corresponding 4-substituted ketoglutaric acids (2a-i), using the enzyme aspartate aminotransferase (AAT) from pig heart or E. coli. The synthesized compounds were evaluated as potential ligands for the glutamate transporters EAAT1, EAAT2, and EAAT3 (excitatory amino acid transporter, subtypes 1-3) in the FLIPR membrane potential (FMP) assay. We found a distinct change in the pharmacological profile when the 4-methyl group (compound 1a, an EAAT1 substrate and EAAT2,3 inhibitor) was extended to a 4-ethyl group, compound 1b, as this analogue is an inhibitor at all three subtypes, EAAT1-3. Furthermore, we conclude that both large and bulky hydrophobic substituents in the 4-position of L-2,4-syn Glu are allowed by all three glutamate transporter subtypes EAAT1-3 while maintaining inhibitory activity.
- Alaux, Sebastien,Kusk, Mie,Sagot, Emanuelle,Bolte, Jean,Jensen, Anders A.,Br?uner-Osborne, Hans,Gefflaut, Thierry,Bunch, Lennart
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p. 7980 - 7992
(2007/10/03)
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- Electrochemical oxidation of substituted amide oximes and 4,5-dihydro-1,2,4-oxadiazoles
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The electrooxidation of several substituted amide oximes to yield the corresponding nitriles, alcohols, and imidate was successfully carried out. The reaction products were dependent on the substituents. Additionally, 4,5-dihydro-1,2,4-oxadiazoles derived from amide oximes were electro-oxidized to afford 1,2,4-oxadiazoles in good yields.
- Okimoto, Mitsuhiro,Takahashi, Yukio
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p. 427 - 428
(2007/10/03)
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- The conversion of 1-propanamine on copper-containing MFI and BEA zeolites prepared by aqueous and vapor ion-exchange
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A process has been developed for exchanging one Cu atom per ion exchange site in an MFI zeolite. The material is synthesized by reaction of the acidic zeolite with CuCl vapor, followed by oxidation with oxygen, and conversion of the Cu2+ species to copper hydroxyl ions and copper hydroxyl dimers by reaction of the oxidized material with water upon exposure to humid air. This material, a similarly prepared BEA material, and copper-containing MFI and BEA zeolites prepared by conventional aqueous ion-exchange have been comparatively investigated for the conversion of 1-propanamine. Reaction products include C6 products such as dipropanamine and 1-propanamine, N-(1-propylidene). A bifunctional acid/metal reaction pathway is proposed to account for the observed products.
- Guidry, Trent F.,Price, Geoffrey L.
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- Silicon Hydrides and Molybdenum(O) Catalyst: A Novel Approach for Conjugate Reduction of α,β-Unsaturated Carbonyl Compounds
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A novel reducing system comprised of phenylsilane and catalytic amounts of Mo(CO)6 in refluxing THF efficiently effects conjugate reduction of Michael acceptors, including α,β-unsaturated ketones, carboxylic acids, carboxylic esters, amides, and nitriles.The process involves molybdenum-catalyzed hydrosilation, followed by hydrolysis of the intermediate silyl enol ether.Hydride is regioselectively transferred from the hydridosilane to the β-carbon of the substrate, and a proton from water is incorporated into the α-carbon.
- Keinan, Ehud,Perez, Daniel
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p. 2576 - 2580
(2007/10/02)
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- Synthetic applications of α-hydroxydiazenes. III. Uncatalyzed and phenol catalyzed hydroalkylation of alkenes and of azobenzene with alkylazodiphenylmethanols
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Alkylazodiphenylmethanols (C6H5)2C(OH)N=NR, (R = CH(CH3)2, CH2CH3, CH3), when decomposed in the presence of olefinic substrates or in the presence of azobenzene, hydroalkylate those substrates.Addition of R and H across the double bond of an unsymmetric alkene occurs with the regiochemistry expected for a radical mechanism, in which the grooup R adds first.Radical intermediates from decomposition of alkylazodiphenylmethanols have been demonstrated earlier with spin trapping experiments.The fact that addition of phenol can enhance the yield of hydroalkylation product suggests that the process is a radical chain reaction, with chain carrying steps consisting of the reactions: (i) R. + CH2=CHY -> RCH2C.HY (ii) RCH2C.HY + (C6H5)2C(OH)N2R -> RCH2CH2Y + (C6H5)2CO + N2 + R..One deuterioalkylation and some yield-optimizing experiments are also reported.
- Yeung, Dominic W. K.,Warkentin, John
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p. 2386 - 2394
(2007/10/02)
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