- S,S-dimethyl dithiocarbonate: A novel carbonyl dication synthon in the synthesis of ketones
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We report herein the use of DMDTC as an effective carbonyl dication equivalent in ketone synthesis. According to our strategy, we also successfully devised a synthetic pathway for S-methyl (trimethylsilyl)thioacetate which may be a potentially useful synthetic reagent in organic synthesis.
- Chen, Chiar-Dy,Huang, Jui-Wen,Leung, Man-Kit,Li, Huei-Hsu
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- Synthesis and characterization of alkyl-imidazolium-based periodic mesoporous organosilicas: A versatile host for the immobilization of perruthenate (RuO4-) in the aerobic oxidation of alcohols
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The preparation and characterization of a set of periodic mesoporous organosilicas (PMOs) that contain different fractions of 1,3-bis(3- trimethoxysilylpropyl)imidazolium chloride (BTMSPI) groups uniformly distributed in the silica mesoporous framework is described. The mesoporous structure of the materials was characterized by powder X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption analysis. The presence of propyl imidazolium groups in the silica framework of the materials was also characterized by solid-state NMR spectroscopy and diffuse-reflectance Fourier-transform infrared spectroscopy. The effect of the BTMSPI concentration in the initial solutions on the structural properties (including morphology) of the final materials was also examined. The total organic content of the PMOs was measured by elemental analysis, whereas their thermal stability was determined by thermogravimetric analysis. Among the described materials, it was found that PMO with 10 % imidazolium content is an effective host for the immobilization of perruthenate through an ion-exchange protocol. The resulting Ru@PI-10 was then employed as a recyclable catalyst in the highly efficient aerobic oxidation of various types of alcohols.
- Karimi, Babak,Elhamifar, Dawood,Yari, Omolbanin,Khorasani, Mojtaba,Vali, Hojatollah,Clark, James H.,Hunt, Andrew J.
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- Site-selective oxidation, amination and epimerization reactions of complex polyols enabled by transfer hydrogenation
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Polyoxygenated hydrocarbons that bear one or more hydroxyl groups comprise a large set of natural and synthetic compounds, often with potent biological activity. In synthetic chemistry, alcohols are important precursors to carbonyl groups, which then can be converted into a wide range of oxygen- or nitrogen-based functionality. Therefore, the selective conversion of a single hydroxyl group in natural products into a ketone would enable the selective introduction of unnatural functionality. However, the methods known to convert a simple alcohol, or even an alcohol in a molecule that contains multiple protected functional groups, are not suitable for selective reactions of complex polyol structures. We present a new ruthenium catalyst with a unique efficacy for the selective oxidation of a single hydroxyl group among many in unprotected polyol natural products. This oxidation enables the introduction of nitrogen-based functional groups into such structures that lack nitrogen atoms and enables a selective alcohol epimerization by stepwise or reversible oxidation and reduction.
- Hill, Christopher K.,Hartwig, John F.
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- C(sp3)-H Bond Acylation with N -Acyl Imides under Photoredox/ Nickel Dual Catalysis
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A novel Ni/photoredox-catalyzed acylation of aliphatic substrates, including simple alkanes and dialkyl ethers, has been developed. The method combines C-N bond activation of amides with a radical relay mechanism involving hydrogen-atom transfer. The protocol is operationally simple, employs bench-stable N -acyl imides as acyl-transfer reagents, and permits facile access to alkyl ketones under very mild conditions.
- Kerackian, Taline,Reina, Antonio,Krachko, Tetiana,Boddaert, Hugo,Bouyssi, Didier,Monteiro, Nuno,Amgoune, Abderrahmane
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- Synthesis of Dialkyl Ketones from Alkenes Using Ph(Et)2N:BH3/CoCl2/CO Reagent System
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Reaction of alkenes with Ph(Et)2N:BH3/CoCl2/Co in THF followed by oxidation gives the corresponding dialkyl ketones.
- Rao, Maddali L. N.,Periasamy, Mariappan
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- Nucleophilic reactivity of a copper(II)-superoxide complex
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Metal-bound superoxide intermediates are often implicated as electrophilic oxidants in dioxygen-activating metalloenzymes. In the nonheme iron α-ketoglutarate dependent oxygenases and pterin-dependent hydroxylases, however, FeIII-superoxide intermediates are postulated to react by nucleophilic attack on electrophilic carbon atoms. By reacting a Cu II-superoxide complex (1) with acyl chloride substrates, we have found that a metal-superoxide complex can be a very reactive nucleophile. Furthermore, 1 was found to be an efficient nucleophilic deformylating reagent, capable of Baeyer-Villiger oxidation of a number of aldehyde substrates. The observed nucleophilic chemistry represents a new domain for metal-superoxide reactivity. Our observations provide support for the postulated role of metal-superoxide intermediates in nonheme iron α-ketoglutarate dependent and pterin-dependent enzymes. Nucleophilic superoxide: A copper(II)-superoxide complex has been found to be a highly reactive nucleophile. The complex reacts readily with certain electrophiles and is capable of the nucleophilic deformylation of electron-rich aldehydes (Baeyer-Villiger oxidation). These observations provide experimental support for the postulated nucleophilic reactivity of metal-superoxide intermediates in the catalytic cycles of certain nonheme iron enzymes.
- Pirovano, Paolo,Magherusan, Adriana M.,McGlynn, Ciara,Ure, Andrew,Lynes, Amy,McDonald, Aidan R.
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- Diisopropyloxy(η2-cyclopentene)titanium for the diastereoselective synthesis of various 1,2-disubstituted cyclopentanes
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The reaction of 3 equiv of cyclopentylmagnesium chloride with 2 equiv of titanium(IV) isopropoxide at low temperature (-70 to -50 °C) leads to the formation of 1 equiv of diisopropyloxy(η2-cyclopentene)titanium containing low amounts of the starting Grignard reagent. The sequential addition of two electrophiles onto this titanium complex involved as an intermediate in Kulinkovich-type reactions delivers various 1,2-disubstituted cyclopentane rings with generally high diastereoselectivity. Mechanistic considerations and possible extensions of this method are discussed.
- Cadoret, Frédéric,Retailleau, Pascal,Six, Yvan
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- Electrochemistry Broadens the Scope of Flavin Photocatalysis: Photoelectrocatalytic Oxidation of Unactivated Alcohols
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Riboflavin-derived photocatalysts have been extensively studied in the context of alcohol oxidation. However, to date, the scope of this catalytic methodology has been limited to benzyl alcohols. In this work, mechanistic understanding of flavin-catalyzed oxidation reactions, in either the absence or presence of thiourea as a cocatalyst, was obtained. The mechanistic insights enabled development of an electrochemically driven photochemical oxidation of primary and secondary aliphatic alcohols using a pair of flavin and dialkylthiourea catalysts. Electrochemistry makes it possible to avoid using O2 and an oxidant and generating H2O2 as a byproduct, both of which oxidatively degrade thiourea under the reaction conditions. This modification unlocks a new mechanistic pathway in which the oxidation of unactivated alcohols is achieved by thiyl radical mediated hydrogen-atom abstraction.
- Zhang, Wen,Carpenter, Keith L.,Lin, Song
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- Synthesis of Ketones and Tertiary Alcohols from Trialkylboranes. Use of Lithium Tris(phenylthio)methanide
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The interaction of lithium tris(phenylthio)methanide with trialkylboranes followed by oxidation allows the production of ketones or tertiary alcohols in good yields under mild conditions.
- Pelter, Andrew,Rao, J. Madhusudhana
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- PET-oxidative cyclization of unsaturated enol silyl ethers
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Unsaturated enol silyl ethers are irradiated in the presence of the electron transfer sensitizer 9, 10-dicyanoanthracene to form silyloxy radical cations which cyclize efficiently to yield cyclic ketones. Cyclization reactions of ε,ζ-unsaturated enol silyl ethers lead exclusively to 6-membered rings.
- Heidbreder, Andreas,Mattay, Jochen
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- Cooperative Electrocatalytic and Chemoselective Alcohol Oxidation by Shvo's Catalyst
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A new electrocatalytic conversion of alcohols to ketones and aldehydes was developed based on an electrochemical study of Shvo's complex. The oxidation of secondary alcohols was efficiently performed under mild conditions using a catalytic amount of Shvo's catalyst, in combination with a sub-stoichiometric amount of 2,6-dimethoxy-1,4-benzoquinone in N,N-dimethylformamide at 80 °C. The hydroquinone thus formed is continuously reoxidized with the aid of an electrochemical device. Excellent yields for different ketones, aromatic as well as aliphatic and α,β-unsaturated ketones, are obtained. In addition, chemoselectivity towards oxidation of the secondary alcohol is achieved when converting vicinal diols such as 1,2-octanediol and 1,2-decanediol. (Figure presented.).
- Lybaert, Jeroen,Trashin, Stanislav,Maes, Bert U. W.,De Wael, Karolien,Abbaspour Tehrani, Kourosch
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- Fragment Couplings via CO2 Extrusion-Recombination: Expansion of a Classic Bond-Forming Strategy via Metallaphotoredox
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In this study we demonstrate that molecular fragments, which can be readily coupled via a simple, in situ RO-C=OR bond-forming reaction, can subsequently undergo metal insertion-decarboxylation-recombination to generate Csp2-Csp3 bonds when subjected to metallaphotoredox catalysis. In this embodiment the conversion of a wide variety of mixed anhydrides (formed in situ from carboxylic acids and acyl chlorides) to fragment-coupled ketones is accomplished in good to high yield. A three-step synthesis of the medicinal agent edivoxetine is also described using this new decarboxylation-recombination protocol.
- Le, C. Chip,MacMillan, David W. C.
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- LITHIUM TRIS(PHENYLTHIO)METHANE FOR THE HOMOLOGATION OF TRIALKYLBORANES: CONVENIENT SYNTHESES OF KETONES AND t-CARBINOLS
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Lithium tris(phenylthio)methane is a readily available, cheap reagent for the production of ketones and t-carbinols from trialkylboranes.The scope and limitations of the reactions are indicated as are some of its unique features.
- Pelter, Andrew,Rao, J. Madhusudhana
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- Catalytic Acceptorless Dehydrogenation of Aliphatic Alcohols
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We developed the first acceptorless dehydrogenation of aliphatic secondary alcohols to ketones under visible light irradiation at room temperature by devising a ternary hybrid catalyst system comprising a photoredox catalyst, a thiophosphate organocatalyst, and a nickel catalyst. The reaction proceeded through three main steps: hydrogen atom transfer from the α-C-H bond of an alcohol substrate to the thiyl radical of the photo-oxidized organocatalyst, interception of the generated carbon-centered radical with a nickel catalyst, and β-hydride elimination. The reaction proceeded in high yield under mild conditions without producing side products (except H2 gas) from various alcohols, including sterically hindered alcohols, a steroid, and a pharmaceutical derivative. This catalyst system also promoted acceptorless cross-dehydrogenative esterification from aldehydes and alcohols through hemiacetal intermediates.
- Fuse, Hiromu,Mitsunuma, Harunobu,Kanai, Motomu
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- Alkane carbonylation photocatalyzed by aromatic ketones under high CO pressure
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Aromatic ketones photocatalyze the carbonylation of alkanes to the corresponding aldehydes at room temperature under high CO pressures (20 - 80 atm). In the presence of CCl4, cyclohexanecarbonylchloride is formed from cyclohexane; this reaction was used to determine the rate of addition of cyclohexyl radical to CO.
- Boese, William T.,Goldman, Alan S.
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- Rapid and Direct Photocatalytic C(sp3)?H Acylation and Arylation in Flow
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Herein, we report a photocatalytic procedure that enables the acylation/arylation of unfunctionalized alkyl derivatives in flow. The method exploits the ability of the decatungstate anion to act as a hydrogen atom abstractor and produce nucleophilic carbon-centered radicals that are intercepted by a nickel catalyst to ultimately forge C(sp3)?C(sp2) bonds. Owing to the intensified conditions in flow, the reaction time can be reduced from 12–48 hours to only 5–15 minutes. Finally, kinetic measurements highlight how the intensified conditions do not change the reaction mechanism but reliably speed up the overall process.
- Bovy, Lo?c,Broersma, Rémy,Mazzarella, Daniele,No?l, Timothy,Pulcinella, Antonio
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supporting information
p. 21277 - 21282
(2021/08/23)
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- Ni-Catalyzed Reductive Carbonylation of Alkyl Halides to Form Dialkyl Ketones Using Diphenyl Oxalate as CO Surrogate
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In this work, we disclosed that diphenyl oxalate serves as a CO surrogate to enable a Ni-catalyzed carbonylation of alkyl bromides/tosylates to afford dialkyl ketones. The reaction shows broad substrate scope and good functional group tolerance.
- Sun, Yuren,Su, Lei,Tong, Weiqi,Yao, Ken,Gong, Hegui
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supporting information
p. 1762 - 1766
(2021/08/13)
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- Base-free oxidation of alcohols enabled by nickel(ii)-catalyzed transfer dehydrogenation
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An efficient nickel(ii)-catalyzed transfer dehydrogenation oxidation of alcohols is reported that relies on cyclohexanone as the formal oxidant and does not require the use of an external base. The synthetic utility of this protocol is demonstratedviathe facile oxidation of structurally complicated natural products.
- Ye, Danfeng,Liu, Zhiyuan,Sessler, Jonathan L.,Lei, Chuanhu
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supporting information
p. 11811 - 11814
(2020/10/13)
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- Decarboxylative Oxygenation via Photoredox Catalysis
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The direct conversion of aliphatic carboxylic acids to their dehomologated carbonyl analogues has been accomplished through photocatalytic decarboxylative oxygenation. This transformation is applicable to an array of carboxylic acid motifs, producing ketones, aldehydes, and amides in excellent yields. Preliminary results demonstrate that this methodology is further amenable to aldehyde substrates via in situ oxidation to the corresponding acid and subsequent decarboxylative oxygenation. We have exploited this strategy for the sequential oxidative dehomologation of linear aliphatic chains.
- Faraggi, Tomer M.,Li, Wei,MacMillan, David W. C.
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p. 410 - 415
(2019/12/24)
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- Synergistic Activation of Amides and Hydrocarbons for Direct C(sp3)–H Acylation Enabled by Metallaphotoredox Catalysis
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The utilizations of omnipresent, thermodynamically stable amides and aliphatic C(sp3)?H bonds for various functionalizations are ongoing challenges in catalysis. In particular, the direct coupling between the two functional groups has not been realized. Here, we report the synergistic activation of the two challenging bonds, the amide C?N and unactivated aliphatic C(sp3)?H, via metallaphotoredox catalysis to directly acylate aliphatic C?H bonds utilizing amides as stable and readily accessible acyl surrogates. N-acylsuccinimides served as efficient acyl reagents for the streamlined synthesis of synthetically useful ketones from simple C(sp3)?H substrates. Detailed mechanistic investigations using both computational and experimental mechanistic studies were performed to construct a detailed and complete catalytic cycle. The origin of the superior reactivity of the N-acylsuccinimides over other more reactive acyl sources such as acyl chlorides was found to be an uncommon reaction pathway which commences with C?H activation prior to oxidative addition of the acyl substrate.
- Baik, Mu-Hyun,Choi, Seulhui,Hong, Soon Hyeok,Lee, Geun Seok,Won, Joonghee
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p. 16933 - 16942
(2020/08/03)
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- Homogeneous oxidation reactions catalysed by in situ-generated triazolylidene copper(I) complexes
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Abstract: Four new Cu complexes bearing triazolylidene ligands 1-(R)-3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium-5-yl: R = phenyl (2a), mesitylenyl (2b), propyl (2c), hexyl (2d) (NHC) were synthesised in high yields. Characterisation by spectroscopic and analytical methods confirmed the molecular composition of the complexes as NHC–Cu-I. The complexes 2(a–d) bearing NHC wingtip variations were tested as in situ-generated catalysts for homogeneous oxidation catalysis with H2O2 as oxidant. The in situ technique was adopted for ease of application and to circumvent the poor stability of the complexes in solution. The results showed that the NHC–Cu-I complexes are capable of initiating oxidation reactions, yielding ketones/aldehydes as dominant products for the oxidation of alkanes under optimised reaction conditions, with complexes bearing aliphatic N-substituents showing the highest catalytic activities. Oxidation of toluene with 2c resulted in a mixture of benzaldehyde and benzyl alcohol as the main products. Also, 2c catalysed the oxidation of n-octane, yielding a mixture of mainly C-8 oxidation products with over 75% selectivity for the isomeric octanones. Analysis of regioselectivity indicated that the internal Csp3–H bonds of n-octane [especially C(2)] are more reactive than the terminal ones. Graphical abstract: [Figure not available: see fulltext.].
- Mncube, Siyabonga G.,Bala, Muhammad D.
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p. 145 - 151
(2018/10/26)
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- From Alkyl Halides to Ketones: Nickel-Catalyzed Reductive Carbonylation Utilizing Ethyl Chloroformate as the Carbonyl Source
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Ketones are an important class of molecules in synthetic and medicinal chemistry. Rapid and modular synthesis of ketones remains in high demand. Described here is a nickel-catalyzed three-component reductive carbonylation method for the synthesis of dialkyl ketones. A wide range of both symmetric and asymmetric dialkyl ketones can be accessed from alkyl halides and a safe CO source, ethyl chloroformate. The approach offers complementary substrate scope to existing carbonylation methods while avoiding the use of either toxic CO or metal carbonyl reagents.
- Shi, Renyi,Hu, Xile
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supporting information
p. 7454 - 7458
(2019/04/30)
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- Iron-catalyzed urea synthesis: Dehydrogenative coupling of methanol and amines
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Substituted ureas have numerous applications but their synthesis typically requires the use of highly toxic starting materials. Herein we describe the first base-metal catalyst for the selective synthesis of symmetric ureas via the dehydrogenative coupling of methanol with primary amines. Using a pincer supported iron catalyst, a range of ureas was generated with isolated yields of up to 80% (corresponding to a catalytic turnover of up to 160) and with H2 as the sole byproduct. Mechanistic studies indicate a stepwise pathway beginning with methanol dehydrogenation to give formaldehyde, which is trapped by amine to afford a formamide. The formamide is then dehydrogenated to produce a transient isocyanate, which reacts with another equivalent of amine to form a urea. These mechanistic insights enabled the development of an iron-catalyzed method for the synthesis of unsymmetric ureas from amides and amines.
- Lane, Elizabeth M.,Hazari, Nilay,Bernskoetter, Wesley H.
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p. 4003 - 4008
(2018/05/04)
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- Chelation-Assisted C-H and C-C Bond Activation of Allylic Alcohols by a Rh(I) Catalyst under Microwave Irradiation
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Chelation-assisted Rh(I)-catalyzed ketone synthesis from allylic alcohols and alkenes through C-H and C-C bond activations under microwave irradiation was developed. Aldimine is formed via olefin isomerization of allyl alcohol under Rh(I) catalysis and condensation with 2-amino-3-picoline, followed by continuous C-H and C-C bond activations to produce a dialkyl ketone. The addition of piperidine accelerates the reaction rate by promoting aldimine formation under microwave conditions.
- Lee, Chang-Hee,Jun, Chul-Ho
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p. 736 - 741
(2017/11/27)
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- Nickel/Photoredox-Catalyzed Amidation via Alkylsilicates and Isocyanates
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A nickel/photoredox, dual-catalyzed amidation reaction between alkylsilicate reagents and alkyl/aryl isocyanates is reported. In contrast to the previously reported reductive coupling process, this protocol is characterized by mild reaction conditions and the absence of a stoichiometric reductant. A mechanistic hypothesis involving a nickel-isocyanate adduct is proposed based on literature precedent and further validation by experimental results.
- Zheng, Shuai,Primer, David N.,Molander, Gary A.
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p. 7957 - 7961
(2017/11/10)
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- Synergistic Photoredox/Nickel Coupling of Acyl Chlorides with Secondary Alkyltrifluoroborates: Dialkyl Ketone Synthesis
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Visible light photoredox/nickel dual catalysis has been employed in the cross-coupling of acyl chlorides with potassium alkyltrifluoroborates. This protocol, based on single-electron-mediated alkyl transfer, circumvents the restriction of using reactive alkylmetallic nucleophiles in transition-metal-catalyzed acylation and achieves a mild and efficient method for the synthesis of unsymmetrical alkyl ketones. In this approach, a variety of acyl chlorides have been successfully coupled with structurally diverse potassium alkyltrifluoroborates, generating the corresponding ketones with good yields.
- Amani, Javad,Molander, Gary A.
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p. 1856 - 1863
(2017/02/10)
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- Selective hydrogenation of arenes to cyclohexanes in water catalyzed by chitin-supported ruthenium nanoparticles
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The selective hydrogenation of aromatic compounds to cyclohexanes was found to be promoted by chitin-supported ruthenium nanoparticles (Ru/chitin) under near-neutral, aqueous conditions without the loss of C-O/C-N linkages at benzylic positions.
- Morioka, Yuna,Matsuoka, Aki,Binder, Kellie,Knappett, Benjamin R.,Wheatley, Andrew E.H.,Naka, Hiroshi
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p. 5801 - 5805
(2016/08/06)
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- Poly(propylene sulfide)-borane: Convenient and versatile reagent for organic synthesis
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Poly(trimethylene sulfide)-borane adduct has been used as an efficient borane reagent in hydroboration reactions to produce various organoboranes, which have then been used without isolation in further reactions that involve single, double and triple migrations of alkyl groups. The presence of the polymer causes no problems, but there are practical advantages associated with its use, including lack of odour and easy recoverability.
- Smith, Keith,Balakit, Asim A.,El-Hiti, Gamal A.
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p. 7834 - 7839
(2012/09/22)
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- Practical one-pot preparation of ketones from aryl and alkyl bromides with aldehydes and DIH via Grignard reagents
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Various diaryl ketones, alkyl aryl ketones, and dialkyl ketones were efficiently prepared in good yields by the reactions of the Grignard reagents derived from aryl or alkyl bromides, followed by the reactions with aromatic or aliphatic aldehydes and the subsequent treatment with 1,3-diiodo-5,5- dimethylhydantoin and K2CO3, in a one-pot method. The same treatment of aromatic bromides bearing electron-withdrawing groups, such as ester, nitrile, ketone, and nitro groups with i-PrMgCl·LiCl or PhMgCl instead of Mg, also provided the corresponding diaryl and alkyl aryl ketones in good yields. The above methods are simple and practical transition-metal-free methods for the preparation of various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatic groups and electron-deficient aromatic groups, as well as dialkyl ketones.
- Dohi, Souya,Moriyama, Katsuhiko,Togo, Hideo
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experimental part
p. 6557 - 6564
(2012/08/27)
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- Synthesis of symmetrical ketones from Grignard reagents and 1,1′-carbonyldiimidazole
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Coupling reactions of 1,1′-carbonyldiimidazole with Grignard reagents provide a rapid and straightforward method for the synthesis of symmetrical ketones. Georg Thieme Verlag Stuttgart.
- Bottalico, Daniela,Fiandanese, Vito,Marchese, Giuseppe,Punzi, Angela
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experimental part
p. 2316 - 2318
(2010/02/28)
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- Tagged hypervalent iodine reagents: A new purification concept based on ion exchange through SN2 substitution
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(Chemical Equation Presented) The preparation of phenylsulfonate-tagged iodine(III) reagents as well as their use in a novel purification strategy for iodine(III)-promoted reactions is described. The concept is based on ion exchange and is initiated by an azide-promoted SN2-reaction at the alkyl sulfonate followed by trapping of the resulting aryl sulfonate anion with an ion-exchange resin. The concept is successfully proven for Ru-catalyzed oxidations of alcohols, the activation and glycosidatlon of thioglycosides, and the Suarez reaction of pyranoses.
- Kunst, Eike,Gallier, Florian,Dujardin, Gilles,Yusubov, Mekhman S.,Kirschning, Andreas
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p. 5199 - 5202
(2008/09/17)
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- Efficient oxidation of cycloalkanols by sodium nitrite with molecular oxygen in trifluoroacetic acid
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Oxidation of aliphatic cycloalkanols by sodium nitrite in trifluoroacetic acid gave α,ω-dicarboxylic acids in good yields. Adipic acid was obtained in a quantitative yield from cyclohexanol using 1 equiv of sodium nitrite under oxygen atmosphere but the oxidation required more than 3 equiv of sodium nitrite under nitrogen atmosphere. The oxidation method was applicable to the conversion of 1-alkanols to the corresponding carboxylic acids.
- Matsumura, Yoshihiro,Yamamoto, Yutaka,Moriyama, Noriaki,Furukubo, Shigeru,Iwasaki, Fumiaki,Onomura, Osamu
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p. 8221 - 8224
(2007/10/03)
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- Tetraethylammonium permanganate. A new selective and mild reagent for deoximation in solvent-free conditions
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A variety of oximes are easily and efficiently cleaved in excellent yields by tetraethylammonium permanganate in a solventless system.
- Bigdeli, Mohammad A.,Alavi Nikje,Heravi, Majid M.
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p. 496 - 497
(2007/10/03)
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- Mechanistic studies on PET-oxidative cyclization of unsaturated silyl enol ethers: Dependence of the regioselectivity on alcohol addition and pressure effects
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Unsaturated silyl enol ethers are irradiated in the presence of electron transfer sensitizers. The efficiency of the cyclization reaction using different sensitizers is investigated. The endo/exo regiochemistry of the ring closure reaction can either be controlled by variation of the silyl group or by addition of alcohol. Furthermore, a dependence of the regiochemistry on pressure is revealed and it seems that it can be related to acetonitrile acting as a nucleophile at 1500 bar. As key intermediates radical cations and radicals are involved.
- Ackermann, Lutz,Heidbreder, Andreas,Wurche, Frank,Klaerner, Frank-Gerrit,Mattay, Jochen
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p. 863 - 869
(2007/10/03)
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- The CoCl2/Ph(Et)2N:BH3/CO system: Reactions of the borane and cobalt carbonyl species
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The CoCl2/Ph(Et)2N:BH3/CO system is useful for the hydroboration and carbonylation of alkenes to obtain the corresponding dialkyl ketones. The cobalt carbonyl species formed in situ in this way is also useful for hydroacylation-cyclisation of norbornene and for the Pauson-Khand reaction.
- Rao, M. Lakshmi Narayana,Periasamy, Mariappan
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- Hindered Organoboron Groups in Organic Chemistry. Part 22. Some Interesting Properties of 2,4,6-Triisopropylphenylborane (Tripylborane, TripBH2, A New Useful Monoarylborane
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2,4,6-Triisopropylphenylborane (tripylborane, TripBH2) is a solid, stable, hydroborating agent that hydroborates monosubstituted alkenes to give either TripBHR1 or TripBR12.TripBHR1 can be converted into mixed boranes TripBR1R2 (R1,R2 = primary alkyl, Rp) and TripBRpRs and TripBRs2 are also readily available.Oxidation of these products gives the corresponding alcohols in excellent yields, with a high selectivity for alkan-1-ols in the cases of groups derived from alk-1-enes.Cyanidation of TripBR2 proceeds to give ketones without migration of the aryl group.This establishes the low migratory aptitude of the aryl group and also that no scrambling of alkyl groups occurs.The tripyl group of TripBRp2 can be selectively removed.
- Smith, Keith,Pelter, Andrew,Jin, Zhao
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p. 395 - 396
(2007/10/02)
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- Carbonylation of R2BI in the presence of NaCo(CO)4 and Na2Fe(CO)4: A simple synthesis of dialkyl ketones
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Reaction of NaCo(CO)4 with R2BI under carbon monoxide at atmospheric pressure at room temperature readily gives the dialkyl ketones in good yields (61-85 percent) after H2O2/OH- oxidation.
- Devasagayaraj, A.,Rao, Narayana M. Lakshmi,Periasamy, M.
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p. 147 - 150
(2007/10/02)
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- Mercury-Photosensitized Sulfination, Hydrosulfination, and Carbonylation of Hydrocarbons: Alkane and Alkene Conversion to Sulfonic Acids, Ketones, and Aldehydes
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Mercury-photosensitized sulfination of alkanes, RH, with SO2 forms sulfinic acids (RSOOH) and sulfinate esters (RSOOR) in high conversion and yield; oxidation of the mixture produces RSO2OH in high yield.Mercury-photosensitized hydrosulfination of alkenes with H2 and SO2 gives RSO2OH after oxidative workup.Mercury-photosensitized carbonylation of alkanes with CO gives RCHO and R2CO.
- Ferguson, Richard R.,Crabtree, Robert H.
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p. 5503 - 5510
(2007/10/02)
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- SYNTHESIS AND APPLICATION OF IMIDAZOLE DERIVATIVES. SYNTHESIS OF (1-METHYL-1H-IMIDAZOL-2-YL)METHANOL DERIVATIVES AND CONVERSION INTO CARBONYL COMPOUNDS
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(1-methyl-2H-imidazol-2-yl)methanol derivatives ( 4 and 7 ) were prepared by treating carbonyl compounds with 2-lithio-1-methyl-1H-imidazole ( 2 ) or by treating 2-acyl-1H-imidazoles ( 3 ) with organometallic reagents or sodium borohydride.The alcohols ( 4 and 7 ) were convertible into the carbonyl compounds via the corresponding quaternary salts ( 8 and 10 ).The stable (1-methyl-1H-imidazol-2-yl)methanol system, , can be regarded as a masked form of the carbonyl group as well as a synthon of the group.Keywords - (1-methyl-1H-imidazol-2-yl)methanol; 2-acyl-1-methyl-1H-imidazole; carbonyl compound synthesis; β-ketoester; protecting group; latent functionality; symmetric ketone; dihydrojasmone
- Ohta, Shunsaku,Hayakawa, Satoshi,Nishimura, Kazuko,Okamoto, Masao
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p. 1058 - 1069
(2007/10/02)
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- α,β-Epoxy Sulfoxides as Useful Intermediates in Organic Synthesis. I. A Novel Synthesis of Dialkyl Ketones and a Synthesis of Aldehydes from Ketones by One Carbon Elongation
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Treatment of α,β-epoxy sulfoxides, prepared from 1-chloroalkyl phenyl sulfoxides with ketones or aldehydes, with sodium benzeneselenolate gives dialkyl ketones or aldehydes in good yields under mild conditions.The mechanism of this reaction and an application of this process to a formal total synthesis of dihydrojasmone are described.
- Satoh, Tsuyoshi,Kaneko, Youhei,Izawa, Takao,Sakata, Kiichi,Yamakawa, Koji
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p. 1983 - 1990
(2007/10/02)
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- A SIMPLE SYNTHESIS OF DIALKYLKETONES FROM ALKENES VIA HYDROBORATION-CARBENOIDATION
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Hydroboration of alkenes with sodium acetoxyborohydride (NaBH3OAc) followed by carbenoidation using NaoCH3/CHCl3 sytem and oxidation with H2O2/NaOH give dialkylketones.
- Narayana, C.,Periasamy, M.
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p. 6361 - 6364
(2007/10/02)
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- IMPROVED SYNTHESIS OF ALIPHATIC KETONES BY THE REACTION OF ALKYLMERCURIC BROMIDES WITH NICKEL CARBONYL IN THE PRESENCE OF POTASSIUM IODIDE
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An improved and convenient procedure for symmetrical aliphatic ketone synthesis is described, which employs the reaction of alkylmercuric bromides with nickel carbonyl in the presence of potassium iodide.
- Ryu, Ilhyong,Ryang, Membo,Rhee, Ilsong,Omura, Haruo,Murai, Shinji,Sonoda, Noboru
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p. 1175 - 1180
(2007/10/02)
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- A NOVEL SYNTHESIS OF DIALKYL KETONES AND α-SULFENYLATED CARBONYL COMPOUNDS FROM α,β-EPOXY SULFOXIDES
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Treatment of α,β-epoxy sulfoides with excess sodium phenylselenide and various kinds of alkylthiolates gave dialkyl ketones and α-sulfenylated carbonyl compounds, respectively, in good yields under mild conditions.
- Satoh, Tsuyoshi,Kaneko, Youhei,Kumagawa, Takumi,Izawa, Takao,Sakata, Kiichi,Yamakawa, Koji
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p. 1957 - 1960
(2007/10/02)
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- Cyanidation Products of Organoboranes Derived from Linalyl Acetate
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The seven-membered cyclic borane obtained from the reaction of linalyl acetate and thexylborane loses 2,3-dimethylbut-2-ene, and the resulting dialkulborane gives an alcohol on treatment with sodium syanide, followed by trifluoroacetic anhydride and oxidation.The structure is confirmed by synthesis.The generality of this reaction was investigated but, of the dialkylboranes examined, only 9-borabicyclononane participated in the cyanidation procedure.A simple synthesis of menthone is presented
- Murphy, Roger,Prager, Rolf H.
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p. 143 - 150
(2007/10/02)
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- EFFET DU BENZENE DANS LA REACTION DE GRIGNARD SUR LES NITRILES
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Use of benzene containing one equivalent of ether as solvent in Grignard reactions of nitriles at room temperature, leads to increased yields of the corresponding ketones compared to results obtained for the same reactions in ether.A useful consequence of this is that undesirable side reactions are virtually eliminated.
- Canonne, Persephone,Foscolos, George B.,Lemay, Gilles
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p. 155 - 158
(2007/10/02)
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- Reactions of organoboranes and 2-lithio-2-alkyl-1,3-benzodithioles. A new, improved synthesis of ketones
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Reactions of trialkylboranes with 2-lithio-2-alkyl-1,3-benzodithioles followed by oxidation give ketones in good yields. This method is far less subject to steric hindrance than the analogous reactions using anions derived from bis(phenylthio)alkanes.
- Ncube, Smollie,Pelter, Andrew,Smith, Keith
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p. 1893 - 1894
(2007/10/09)
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