- Catalytic Radical Trifluoromethylalkynylation of Unactivated Alkenes
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The trifluoromethylalkynylation of unactivated alkenes with alkynyl sulfones and Togni's reagent was developed. The reaction was catalyzed by 2,4,6-trimethylpyridine, leading to various β-trifluoromethylated alkynes under metal-free conditions with a broad substrate scope and wide functional group compatibility. A mechanism involving catalytic nonchain radical processes is proposed.
- Zhou, Shaofang,Song, Tao,Chen, He,Liu, Zhonglin,Shen, Haigen,Li, Chaozhong
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- Chemoselective reduction of ?,¢-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
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The selective reduction of ?,¢-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ¢ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ¢-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
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p. 590 - 599
(2021/03/29)
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- Visible-Light Decatungstate/Disulfide Dual Catalysis for the Hydro-Functionalization of Styrenes
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We describe an efficient photoredox system, relying on decatungstate/disulfide catalysts, for the hydrofunctionalization of styrenes. In this methodology the use of disulfide as a cocatalyst was shown to be crucial for the reaction efficiency. This photoredox system was employed for the hydro-carbamoylation, -acylation, -alkylation, and -silylation of styrenes, giving access to a large variety of useful building blocks and high-value molecules such as amides and unsymmetrical ketones from simple starting materials.
- Prieto, Alexis,Taillefer, Marc
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supporting information
p. 1484 - 1488
(2021/03/08)
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- Preparation of 2-Arylquinolines from 2-Arylethyl Bromides and Aromatic Nitriles with Magnesium and N -Iodosuccinimide
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Treatment of 2-arylethylmagnesium bromides, prepared from 2-arylethyl bromides and magnesium, with aromatic nitriles, followed by reaction with water and then with N -iodosuccinimide under irradiation with a tungsten lamp, gave the corresponding 2-arylquinolines in good to moderate yields under transition-metal-free conditions. 2-Alkylquinolines could be also obtained in moderate yields by the same procedure with 2-arylethyl bromides, magnesium, aliphatic nitriles bearing a secondary alkyl group, and N -iodosuccinimide.
- Naruto, Hiroki,Togo, Hideo
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p. 1122 - 1130
(2020/04/01)
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- Visible-Light-Promoted Catalytic Ring-Opening Isomerization of 1,2-Disubstituted Cyclopropanols to Linear Ketones
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Isomerization to linear ketones is a valuable transformation of 1,2-disubstituted cyclopropanols proceeding through radical intermediates. Despite simplicity of this reaction, the known protocol required stoichiometric amounts of both an oxidant and a reducing agent. In this article, we report a catalytic isomerization of 1,2-disubstituted cyclopropanols to linear ketones enabled by the photoredox catalytic system consisting of an acridinium photocatalyst and diphenyl disulfide under irradiation with blue LEDs.
- Laktsevich-Iskryk, Marharyta V.,Varabyeva, Nastassia A.,Kazlova, Volha V.,Zhabinskii, Vladimir N.,Khripach, Vladimir A.,Hurski, Alaksiej L.
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p. 2431 - 2434
(2020/04/20)
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- Conversion of Aldehydes to Branched or Linear Ketones via Regiodivergent Rhodium-Catalyzed Vinyl Bromide Reductive Coupling-Redox Isomerization Mediated by Formate
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A regiodivergent catalytic method for direct conversion of aldehydes to branched or linear alkyl ketones is described. Rhodium complexes modified by PtBu2Me catalyze formate-mediated aldehyde-vinyl bromide reductive coupling-redox isomerization to form branched ketones. Use of the less strongly coordinating ligand, PPh3, promotes vinyl-to allylrhodium isomerization en route to linear ketones. This method bypasses the 3-step sequence often used to convert aldehydes to ketones involving the addition of pre-metalated reagents to Weinreb or morpholine amides.
- Swyka, Robert A.,Shuler, William G.,Spinello, Brian J.,Zhang, Wandi,Lan, Chunling,Krische, Michael J.
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supporting information
p. 6864 - 6868
(2019/05/10)
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- Enamines as Surrogates of Alkyl Carbanions for the Direct Conversion of Secondary Amides to α-Branched Ketones
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A direct transformation of secondary amides into α-branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot coupling of secondary amides with aldehydes to yield ketones. (Figure presented.).
- Liu, Yong-Peng,Wang, Shu-Ren,Chen, Ting-Ting,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
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supporting information
p. 971 - 975
(2019/01/25)
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- Alkylation of Ketones Catalyzed by Bifunctional Iron Complexes: From Mechanistic Understanding to Application
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Cyclopentadienone iron dicarbonyl complexes were applied in the alkylation of ketones with various aliphatic and aromatic ketones and alcohols via the borrowing hydrogen strategy in mild reaction conditions. DFT calculations and experimental works highlight the role of the transition metal Lewis pairs and the base. These iron complexes demonstrated a broad applicability in mild conditions and extended the scope of substrates.
- Seck, Charlotte,Mbaye, Mbaye Diagne,Coufourier, Sébastien,Lator, Alexis,Lohier, Jean-Fran?ois,Poater, Albert,Ward, Thomas R.,Gaillard, Sylvain,Renaud, Jean-Luc
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p. 4410 - 4416
(2017/11/20)
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- Radical-Based C?C Bond-Forming Processes Enabled by the Photoexcitation of 4-Alkyl-1,4-dihydropyridines
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We report herein that 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) can directly reach an electronically excited state upon light absorption and trigger the generation of C(sp3)-centered radicals without the need for an external photocatalyst. Selective excitation with a violet-light-emitting diode turns alkyl-DHPs into strong reducing agents that can activate reagents through single-electron transfer manifolds while undergoing homolytic cleavage to generate radicals. We used this photochemical dual-reactivity profile to trigger radical-based carbon–carbon bond-forming processes, including nickel-catalyzed cross-coupling reactions.
- Buzzetti, Luca,Prieto, Alexis,Roy, Sudipta Raha,Melchiorre, Paolo
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supporting information
p. 15039 - 15043
(2017/11/20)
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- Method for synthesizing alpha-alkyl ketone
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The invention discloses a method for synthesizing alpha-alkyl ketone, and especially includes the following steps of: in a reaction vessel, adding secondary alcohol, a transition metal catalyst, and a solvent tertiary amyl alcohol; and heating and refluxing a reaction mixture in an oil bath for several hours, cooling the mixture to a room temperature; then adding primary alcohol and alkali, heating and refluxing the reaction mixture for several hours, and then obtaining a target compound through column separation. The method for synthesizing the alpha-alkyl ketone starts from the primary alcohol and the secondary alcohol. With the participation of the transition metal catalyst, the alpha-alkyl ketone is generated through a serial secondary alcohol non-acceptor dehydrogenation oxidation reaction/alpha-alkylation reaction of ketone. The reaction shows three obvious advantages that 1) non-toxic alcohols are used as the starting materials; 2) only hydrogen and water are generated in the reaction without environmental hazards; 3) atomic economy is high in the reaction; and 4) only 0.1 equivalents of carbonate is needed for the reaction, and the reaction only takes 3-6 hours. Therefore, the reaction meets the requirements of green chemistry and has broad development prospects.
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Paragraph 0173; 0174; 0175; 0176; 0177
(2017/04/12)
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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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- Bifunctional Ru(II) complex catalysed carbon-carbon bond formation: an eco-friendly hydrogen borrowing strategy
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The atom economical borrowing hydrogen methodology enables the use of alcohols as alkylating agents for selective C-C bond formation. A bifunctional 2-(2-pyridyl-2-ol)-1,10-phenanthroline (phenpy-OH) based Ru(ii) complex (2) was found to be a highly efficient catalyst for the one-pot β-alkylation of secondary alcohols with primary alcohols and double alkylation of cyclopentanol with different primary alcohols. Exploiting the metal-ligand cooperativity in complex 2, several aromatic, aliphatic and heteroatom substituted alcohols were selectively cross-coupled in high yields using significantly low catalyst loading (0.1 mol%). An outer-sphere mechanism is proposed for this system as exogenous PPh3 has no significant effect on the rate of the reaction. Notably, this is a rare one-pot strategy for β-alkylation of secondary alcohols using a bifunctional Ru(ii)-complex. Moreover, this atom-economical methodology displayed the highest cumulative turn over frequency (TOF) among all the reported transition metal complexes in cross coupling of alcohols.
- Chakrabarti, Kaushik,Paul, Bhaskar,Maji, Milan,Roy, Bivas Chandra,Shee, Sujan,Kundu, Sabuj
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p. 10988 - 10997
(2016/12/06)
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- General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand
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Remarkably simple IrIIIcatalysts enable the isomerization of primary and sec-allylic alcohols under very mild reaction conditions. X-ray absorption spectroscopy (XAS) and mass spectrometry (MS) studies indicate that the catalysts, with the general formula [Cp*IrIII], require a halide ligand for catalytic activity, but no additives or additional ligands are needed.
- Erbing, Elis,Vázquez-Romero, Ana,Bermejo Gómez, Antonio,Platero-Prats, Ana E.,Carson, Fabian,Zou, Xiaodong,Tolstoy, P?ivi,Martín-Matute, Belén
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p. 15659 - 15663
(2016/10/25)
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- Nickel-Catalyzed Hydroacylation of Styrenes with Simple Aldehydes: Reaction Development and Mechanistic Insights
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The first nickel-catalyzed intermolecular hydroacylation reaction of alkenes with simple aldehydes has been developed. This reaction offers a new approach to the selective preparation of branched ketones in high yields (up to 99%) and branched selectivities (up to 99:1). Experimental data provide evidence for reversible formation of acyl-nickel-alkyl intermediate, and DFT calculations show that the aldehyde C-H bond transfer to a coordinated alkene without oxidative addition is involved. The origin of the reactivity and regioselectivity of this reaction was also investigated computationally, which are consistent with experimental observations.
- Xiao, Li-Jun,Fu, Xiao-Ning,Zhou, Min-Jie,Xie, Jian-Hua,Wang, Li-Xin,Xu, Xiu-Fang,Zhou, Qi-Lin
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supporting information
p. 2957 - 2960
(2016/03/19)
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- Synthesis of a-Alkylated Ketones via Tandem Acceptorless Dehydrogenation/a-Alkylation from Secondary and Primary Alcohols Catalyzed by Metal-Ligand Bifunctional Iridium Complex [CpIr(2,2′-bpyO)(H2O)]
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A new strategy for the synthesis of α-alkylated ketones via tandem acceptorless dehydrogenation/α-alkylation from secondary and primary alcohols was proposed and accomplished. In the presence of metal-ligand bifunctional iridium complex [CpIr(2,2′-bpyO)(H2O)], various desirable products were obtained in high yields. Compared with previous methods for the direct dehydrogenative coupling of secondary alcohols with primary alcohols to α-alkylated ketones, this protocol has obvious advantages including complete selectivity for α-alkylated ketones and more environmentally benign conditions. Notably, the study also exhibited the potential to develop tandem reactions catalyzed using a metal-ligand bifunctional iridium complex.
- Wang, Rongzhou,Ma, Juan,Li, Feng
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p. 10769 - 10776
(2015/11/18)
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- Michael Addition of Soft Carbon Nucleophiles to Alkylidene Isoxazol-5-ones: A Divergent Entry to β-Branched Carbonyl Compounds
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A novel, divergent strategy toward the synthesis of β-branched (and linear) carbonyl compounds is developed by taking advantage of alkylidene isoxazol-5-ones as key building blocks. The yields obtained range from good to excellent, therefore making the described methods attractive options for building such molecules. (Chemical Equation).
- Capreti, Naylil M. R.,Jurberg, Igor D.
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supporting information
p. 2490 - 2493
(2015/05/27)
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- Scope and mechanism in palladium-catalyzed isomerizations of highly substituted allylic, homoallylic, and alkenyl alcohols
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Herein we report the palladium-catalyzed isomerization of highly substituted allylic alcohols and alkenyl alcohols by means of a single catalytic system. The operationally simple reaction protocol is applicable to a broad range of substrates and displays a wide functional group tolerance, and the products are usually isolated in high chemical yield. Experimental and computational mechanistic investigations provide complementary and converging evidence for a chain-walking process consisting of repeated migratory insertion/β-H elimination sequences. Interestingly, the catalyst does not dissociate from the substrate in the isomerization of allylic alcohols, whereas it disengages during the isomerization of alkenyl alcohols when additional substituents are present on the alkyl chain.
- Larionov, Evgeny,Lin, Luqing,Gune, Laure,Mazet, Clment
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supporting information
p. 16882 - 16894
(2015/01/09)
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- Rhodium-catalyzed ketone methylation using methanol under mild conditions: Formation of α-branched products
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The rhodium-catalyzed methylation of ketones has been accomplished using methanol as the methylating agent and the hydrogen-borrowing method. The sequence is notable for the relatively low temperatures that are required and for the ability of the reaction system to form α-branched products with ease. Doubly alkylated ketones can be prepared from methyl ketones and two different alcohols by using a sequential one-pot iridium- and rhodium-catalyzed process. Uniquely effective for making branched alkyl products from ketones (see scheme): The scope of the presented reaction includes aromatic and aliphatic ketones and consecutive one-pot double alkylation reactions to provide a convenient route to branched ketones from simple methyl ketones. A brief study into the mechanism of the reaction has given evidence for an aldol-based reaction pathway.
- Chan, Louis K. M.,Poole, Darren L.,Shen, Di,Healy, Mark P.,Donohoe, Timothy J.
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supporting information
p. 761 - 765
(2014/01/23)
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- Chemoselective transfer hydrogenation of α,β-unsaturated ketones catalyzed by pincer-Pd complexes using alcohol as a hydrogen source
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A pincer-Pd complex was utilized in the chemoselective transfer hydrogenation of α,β-unsaturated ketones using n-BuOH as a hydrogen source and solvent. Good to excellent yields were obtained for various substrates even with reducible groups. Based on deuterium-labeling experiments, the reaction mechanism is proposed to occur via a pincer-Pd-hydride intermediate.
- Ding, Boqiang,Zhang, Zhenfeng,Liu, Yangang,Sugiya, Masashi,Imamoto, Tsuneo,Zhang, Wanbin
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p. 3690 - 3693
(2013/08/23)
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- Stereospecific intramolecular C-H amination of 1-aza-2-azoniaallene salts
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We report that 1-aza-2-azoniaallene salts, generated from α-chloroazo compounds by treatment with halophilic Lewis acids, participate in intramolecular C-H amination reactions to provide pyrazoline products in good to excellent yield. This intramolecular amination occurs readily at both benzylic and tertiary aliphatic positions and proceeds at an enantioenriched chiral center without loss of enantiomeric excess. A competition reaction shows that insertion occurs more readily at an electron-rich benzylic position than an electron-deficient one. These observations are consistent with the 1-aza-2-azoniaallene intermediate reacting as a nitrenium-like ion by a concerted insertion mechanism.
- Bercovici, Daniel A.,Brewer, Matthias
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supporting information; body text
p. 9890 - 9893
(2012/08/08)
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- C-X (X=Br, I) bond-tolerant aerobic oxidative cross-coupling: A strategy to selectively construct β-aryl ketones and aldehydes
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Using moelcular oxygen as the terminal oxidant, various aryl halide-containing β-aryl ketones and aldehydes can be synthesized directly from readily available allyic alcohols and boronic acids via palladium-catalyzed oxidative cross-coupling reactions. The dual roles of copper, including electron-carrier and Lewis acid functions, are supposed to be critical for the high reactivity and selectivity of this aerobic oxidative coupling transformation. Copyright
- Chen, Mao,Wang, Jie,Chai, Ziyi,You, Cai,Lei, Aiwen
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supporting information; experimental part
p. 341 - 346
(2012/05/04)
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- Cyanocuprates convert carboxylic acids directly into ketones
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Carboxylic acids were converted directly in 56-99% yields into methyl, n-butyl, and isopropyl ketones using excess cyanocuprates R2CuLi 3 LiCN. A substrate with a stereocenter α to the carboxylic acid was converted into ketones with very little loss of enantiomeric purity. A variety of functional groups were tolerated including aryl bromides. This direct transformation of a carboxylic acid into ketone with minimal tertiary alcohol formation is proposed to involve a relatively stable copper ketal tetrahedral intermediate.
- Genna, Douglas T.,Posner, Gary H.
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supporting information; experimental part
p. 5358 - 5361
(2011/12/15)
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- A tertiary amine as a hydride donor: Trichlorosilyl triflate-mediated conjugate reduction of unsaturated ketones
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Bulky tertiary amines, especially dicyclohexylisobutylamine, smoothly reduced α,β-unsaturated ketones in the presence of trichlorosilyl triflate to give the corresponding saturated ketones in excellent yields. Isotope-labeling studies revealed that an α-hydrogen of the amine was transferred to the enones during reduction.
- Kotani, Shunsuke,Osakama, Kazuki,Sugiura, Masaharu,Nakajima, Makoto
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supporting information; experimental part
p. 3968 - 3971
(2011/09/16)
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- Chemoselective conjugate reduction of α,β-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media
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Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C-O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C-O to C-C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones. Now we have found that a variety of α,β-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.
- Li, Xuefeng,Li, Liangchun,Tang, Yuanfu,Zhong, Ling,Cun, Linfeng,Zhu, Jin,Liao, Jian,Deng, Jingen
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supporting information; experimental part
p. 2981 - 2988
(2010/07/05)
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- A ruthenium-catalyzed one-pot method for α-alkylation of ketones with aldehydes
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Ketones react with an array of aldehydes in dioxane at 80 °C in the presence of a catalytic amount of RuCl2(PPh3)3 along with KOH to give the corresponding α-alkylated ketones in moderate to good yields. A reaction pathway involving base-catalyzed cross-aldol reaction between ketones and aldehydes to form α,β-unsaturated ketones and regioselective reduction of carbon-carbon double bond of α,β-unsaturated ketones is proposed for this catalytic process.
- Cho, Chan Sik,Shim, Sang Chul
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p. 4329 - 4332
(2007/10/03)
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- Recyclable palladium catalyst for highly selective α alkylation of ketones with alcohols
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(Chemical Equation Presented) An air-stable, heterogeneous, and recyclable catalyst composed of palladium nanoparticles entrapped in aluminum hydroxide was applied to a highly selective α alkylation. A wide range of aliphatic and aromatic ketones and primary alcohols were coupled to prepare enones in an O2 atmosphere and ketones in an argon atmosphere (see scheme).
- Kwon, Min Serk,Kim, Namdu,Seo, Seong Hyeok,Park, In Soo,Cheedrala, Ravi Kumar,Park, Jaiwook
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p. 6913 - 6915
(2007/10/03)
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- HIV protease inhibitors
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The present invention relates to novel dihydropyrones with tethered heterocycles having improved pharmacologic properties which potently inhibit the HIV aspartyl protease blocking HIV infectivity. The dihydropyrones are useful in the development of therapies for the treatment of viral infections and diseases, including AIDS. The present invention is also directed to methods of synthesis of the dihydropyrones and intermediates useful in the preparation of the final compounds.
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- Ruthenium-catalyzed regioselective α-alkylation of ketones with primary alcohols
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Ketones are regioselectively alkylated with an array of primary alcohols in dioxane at 80°C in the presence of a catalytic amount of a ruthenium catalyst together with KOH and a hydrogen acceptor.
- Cho, Chan Sik,Kim, Bok Tae,Kim, Tae-Jeong,Chul Shim, Sang
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p. 7987 - 7989
(2007/10/03)
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- Substituted guanidine derivatives and process for producing the same
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A compound represented by the general formula (1): wherein each of R1, R2, R3, R4and R5is a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, a saturated heterocyclic group, an aromatic group, an acyl group or the like; each of Y1, Y2, Y3and Y4is a single bond, —CH2—, —O—, —CO— or the like, provided that at least two of Y1through Y4are independently a group other than a single bond; and Z may be absent, or one or more Zs may be present and are independently an alkyl group, a substituted alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, a saturated heterocyclic group, a halogen atom, a carboxyl group, an alkoxycarbonyl group, an aromatic group, an acyl group or the like, is useful as a therapeutic or prophylactic agent for diseases caused by the acceleration of the sodium/proton exchange transport system.
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Page column 66-67
(2010/01/31)
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- Arylation of α-substituted acrylates in ionic liquids catalyzed by a Pd-benzothiazole carbene complex
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A Pd-catalyst with benzothiazole carbene as ligands allows, in tetrabutylammonium bromide melt as solvent, very fast and efficient reactions of bromoaromatics with 3-hydroxy-2-methylenealkanoates to give β-arylketones.
- Calò, Vincenzo,Nacci, Angelo,Lopez, Luigi,Napola, Annalisa
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p. 4701 - 4703
(2007/10/03)
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- Pd-catalyzed ring opening of cyclopropanols
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Treatment of substituted cyclopropanols with a Pd catalyst in MeCN at 50 °C gave enones in good yields.
- Okumoto, Hiroshi,Jinnai, Takamitsu,Shimizu, Hiroyuki,Harada, Yoshinori,Mishima, Hideki,Suzuki, Akira
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p. 629 - 630
(2007/10/03)
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- Cyclialkylation of arylalkyl epoxides with solid acid catalysts
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Solid acids, such as zeolites and clays, catalyse the intramolecular hydroxyalkylation (cyclialkylation) of several arylalkyl epoxides in moderate to excellent conversions and selectivities. The use of solid acids in these cyclialkylations provides a cleaner, better alternative to conventional Lewis and Bronsted acids, enabling a more facile workup of reaction mixtures and, in several cases, better selectivities.
- Elings, Jacob A.,Downing, Roger S.,Sheldon, Roger A.
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p. 837 - 846
(2007/10/03)
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- Reactions of in situ formed acyl tributylphosphonium ions with Grignard reagents as an effective route to ketones from acid chlorides
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The reactions of acyl tributylphosphonium ions in situ generated from acid chlorides and Bu3P in THF at -22°C with primary alkyl and arylmagnesium halides have proved to be a convenient and simple procedure to prepare ketones from acid chloride in one-pot.
- Maeda, Hatsuo,Okamoto, Junko,Ohmori, Hidenobu
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p. 5381 - 5384
(2007/10/03)
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- Novel Routes to Enol Ethers, Unsymmetrical Ketones, α-Bromoalkyl Ketones, 1,4-Diketones, 2-Ethoxy-2-cyclopenetenones, and α-Keto Enamines
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Highly regioselectve SN2' reactions of adducts 6 (readily prepared by reactions of halides with the allyl anion 12 of 11) with Grignard reagents gave enol ethers 13, which were converted (in one-pot reactions from 11) into ketones 14 and α-bromoalkyl ketones 15 in good yields.The monoprotected 1,4-diketone derivative 16 (prepared by Michael addition of the allyl anion 12 with methyl vinyl ketone) was converted both into 1,4-diketones 18 and into protected γ-hydroxyalkyl ketone 20 by propenoyl, or to both functionalities.The allyl anion 12 with α-substituted acetic esters gave α-acylated adducts 24, which underwent in situ unfavored endo-trig cyclization upon treatment with NaH and secondary amines, to give 2-ethoxy-2-cyclopenetenones 27 and 28 and α-keto enamines 25 in good yield.The mechanism for the cyclization is discussed.
- Katritzky, Alan R.,Zhang, Guifen,Jiang, Jinlong
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p. 7605 - 7611
(2007/10/03)
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- New Method for Generation of β-Oxido Carbenoid via Ligand Exchange Reaction of Sulfoxides: A Versatile Procedure for One-Carbon Homologation of Carbonyl Compounds
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A new procedure for one-carbon homologation of carbonyl compounds is described.The method is based on the rearrangement of β-oxido carbenoid which is generated via the ligand exchange reaction of the sulfinyl group of α-chloro β-hydroxy sulfoxide with tert-butyllithium.Addition of the carbanion of aryl 1-chloroalkyl sulfoxides to carbonyl compounds gave the adducts in good yields.The β-oxido carbenoid rearrangement of the adducts gave one-carbon homologated carbonyl compounds having an α-alkyl substituent.A similar reaction of the adducts derived from carbonyl compounds with chloromethyl p-tolyl sulfoxide yielded a procedure for a methylene insertion.The stereochemistry of the β-oxido carbenoid rearrangenment is also discussed.
- Satoh, Tsuyoshi,Itoh, Norifumi,Gengyo, Kaoru,Takada, Sae,Asakawa, Naoyuki,et al.
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p. 11839 - 11852
(2007/10/02)
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- 1-Haloalkyl Aryl Sulfoxides as Useful Agents in Synthesis of α-Halo Ketones: A New Synthesis of α-Halo Ketones, α-Halo α,β-Unsaturated Ketones, and α-Halo Cross Dienones from Aldehydes
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α-Halo α-sulfinyl ketones were synthesized in two steps from 1-haloalkyl aryl sulfoxides and aldehydes in high yields.Desulfinylation of the α-halo α-sulfinyl ketones was performed with ethylmagnesium bromide in ether at low temperature to afford α-halo ketones via magnesium enolates in high yields.The magnesium enolate intermediates were trapped with various electrophiles such as deuterium oxide, ethyl chloroformate, and chlorotrimethylsilane.Trapping of the magnesium enolate intermediate with carbonyl compounds afforded a new type of the directed aldol reaction.Desulfi nylation of the sulfinyl group of the α-halo α-sulfinyl ketones under thermal conditions gave α-halo α,β-unsatureted ketones or α-halo cross dienones.
- Satoh, Tsuyoshi,Itoh, Norifumi,Onda, Ken-ichi,Kitoh, Yasushi,Yamakawa, Koji
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p. 2800 - 2806
(2007/10/02)
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- α-Benzylation of Ketones by Reaction with Benzylamine. Regioselective Reduction of C-C Double Bonds in Cohjugated Enones
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Prolonged reaction of some ketones with benzylamine at reflux converts them into α-benzyl derivatives by a route involving Aldol condensation of the related ketimine with benzaldimine followed by exclusive reduction of the resultant C-C double bond.Reduction does not occur when pure benzylamine is used under oxygen-free nitrogen, however the inclusion of a trace of benzaldehyde restores the efficiency of the reaction.Treatment of several ketones in this manner established the scope of the process.When the reaction was extended to the reduction of α,β-unsaturated enones again using benzylamine, reaction times were shorter and the product yield greater.The possibility that the reductive step was an intramolecular 1,5-hydrogen transfer was studied.
- Armesto, Diego,Esteban, Soledad,Horspool, William M.,Martin, Juan-Antonio F.,Martinez-Alcazar, Paz,Perez-Ossorio, Rafael
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p. 751 - 755
(2007/10/02)
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- Friedel-Crafts Cyclialkylations of Some Epoxides. 3. Cyclizations of Tertiary and Meta-Substituted Arylalkyl Epoxides
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The intramolecular cyclization of aryl groups to tertiary epoxide position was investigated, and the results were used to test the applicability of Baldwin's rules to this specific class of reactions.As a probe into mechanism of reactions studied earlier, the cyclizations of some meta-substituted 1,2-epoxy-5-phenylpentanes were examined to determine positional selectivities.The data obtained were compared with those of other studies, and comments are made on the reaction mechanism.
- Taylor, Stephen K.,Blankespoor, Curtis L.,Harvey, Suzanne M.,Richardson, Lynell J.
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p. 3309 - 3312
(2007/10/02)
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- SIMPLE AND CHEMOSELECTIVE SYNTHESIS OF KETONES FROM CARBOXYLIC ACIDS AND GRIGNARD REAGENTS USING DICHLOROTRIPHENYLPHOSPHORANE
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Dichlorotriphenylphosphorane was found to be a good condensation reagent for synthesis of ketones from carboxylic acids and Grignard reagents under mild conditions.Synthetic utility of the present method is demonstrated by the chemoselective reaction of carboxylic acids possessing such a functional group as halogen, cyano, or carbonyl.
- Fujisawa, Tamotsu,Iida, Sachio,Uehara, Hiroshi,Sato, Toshio
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p. 1267 - 1270
(2007/10/02)
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- ONE-POT SYNTHESIS OF KETONES FROM CARBOXYLIC ACIDS AND GRIGNARD REAGENTS USING N,N-DIPHENYL-p-METHOXYPHENYLCHLOROMETHYLENIMINIUM CHLORIDE
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N,N-Diphenyl-p-methoxyphenylchloromethyleniminium chloride is found to be an effective condensation reagent of carboxylic acids and Grignard reagents under mild conditions to afford the corresponding ketones in high yields.
- Fujisawa, Tamotsu,Mori, Toshiki,Sato, Toshio
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p. 5059 - 5062
(2007/10/02)
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- THE REACTION BETWEEN KETONES AND THIONYL CHLORIDE
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The reaction between thionyl chloride and ketones gives rise to a variety of products depending both on the structure of the ketone and on the reaction conditions.Two rules have been formulated enabling the initial reaction product to be predicted.Some reactions involving sulphuryl chloride have also been discussed.
- Pizey, James F.,Symeonides, Kyriakos
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