- Rh-Catalyzed Coupling of Aldehydes with Allylboronates Enables Facile Access to Ketones
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We present herein a novel strategy for the preparation of ketones from aldehydes and allylic boronic esters. This reaction involves the allylation of aldehydes with allylic boronic esters and the Rh-catalyzed chain-walking of homoallylic alcohols. The key to this successful development is the protodeboronation of alkenyl borylether intermediate via a tetravalent borate anion species in the presence of KHF2 and MeOH. This approach features mild reaction conditions, broad substrate scope, and excellent functional group tolerance. Mechanistic studies also supported that the tandem allylation and chain-walking process were involved.
- Zhang, Kezhuo,Huang, Jiaxin,Zhao, Wanxiang
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supporting information
(2022/02/21)
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- Light-Driven Carbene Catalysis for the Synthesis of Aliphatic and α-Amino Ketones
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Single-electron N-heterocyclic carbene (NHC) catalysis has gained attention recently for the synthesis of C?C bonds. Guided by density functional theory and mechanistic analyses, we report the light-driven synthesis of aliphatic and α-amino ketones using single-electron NHC operators. Computational and experimental results reveal that the reactivity of the key radical intermediate is substrate-dependent and can be modulated through steric and electronic parameters of the NHC. Catalyst potential is harnessed in the visible-light driven generation of an acyl azolium radical species that undergoes selective coupling with various radical partners to afford diverse ketone products. This methodology is showcased in the direct late-stage functionalization of amino acids and pharmaceutical compounds, highlighting the utility of single-electron NHC operators.
- Bay, Anna V.,Cheong, Paul Ha-Yeon,Farah, Abdikani Omar,Fitzpatrick, Keegan P.,González-Montiel, Gisela A.,Scheidt, Karl A.
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supporting information
p. 17925 - 17931
(2021/07/17)
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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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- 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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- Isolation and Characterization of Regioisomers of Pyrazole-Based Palladacycles and Their Use in α-Alkylation of Ketones Using Alcohols
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Regioisomers of 3,5-diphenyl-1-(4-(trifluoromethyl)phenyl)-1H-pyrazole-based palladacycles (1 and 2) were synthesized by the aromatic C-H bond activation of N/3-aryl ring. The application of these regioisomers as catalysts to enable the formation of α-alkylated ketones or quinolines with alcohols using a hydrogen borrowing process is evaluated. Experimental results reveal that palladacycle 2 is superior over palladacycle 1 to catalyze the reaction under similar reaction conditions. The reaction mechanisms for the palladacycles 1 and 2 catalyzed α-alkylation of acetophenone were studied using density functional theoretical (DFT) methods. The DFT studies indicate that palladacycle 2 has an energy barrier lower than that of palladacycle 1 for the alkylation reaction, consistent with the better catalytic activity of palladacycle 2 seen in the experiments. The palladacycle-phosphine system was found to tolerate a wide range of functional groups and serves as an efficient protocol for the synthesis of α-alkylated products under solvent-free conditions. In addition, the synthetic protocol was successfully applied to prepare donepezil, a drug for Alzheimer's disease, from simple starting materials.
- Mamidala, Ramesh,Samser, Shaikh,Sharma, Nishant,Lourderaj, Upakarasamy,Venkatasubbaiah, Krishnan
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supporting information
p. 3343 - 3351
(2017/09/18)
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- Selective Aerobic Oxidation of Primary Alcohols to Aldehydes
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The 2-azaadamantane- N -oxyl (AZADO)- and 9-azanoradamantane- N -oxyl (nor-AZADO)-catalyzed selective oxidation of primary alcohols to the corresponding aldehydes is described. The use of tert -butyl nitrite as the co-catalyst enables efficient aerobic oxidation in MeCN instead of previously reported AcOH; this is important for the selectivity of the reaction. The addition of a solution of saturated aqueous NaHCO 3 after the completion of the reaction was effective to suppress the overoxidation of the product to the corresponding carboxylic acid during the workup.
- Shibuya, Masatoshi,Furukawa, Keisuke,Yamamoto, Yoshihiko
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p. 1554 - 1557
(2017/08/11)
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- Palladium-Catalyzed Desulfitative Oxidative Coupling between Arenesulfinic Acid Salts and Allylic Alcohols: A Strategy for the Selective Construction of β-Aryl Ketones and Aldehydes
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An efficient palladium-catalyzed desulfitative oxidative coupling of sodium arylsulfinites for highly region-selective Heck-type reaction of allylic alcohols has been developed. The compatibility of the functionalities of -I, -Br, and -F would explore further postfunctionalization of the C-X bonds. This method provides a new and straightforward protocol for the synthesis of β-aryl ketones and aldehydes. The deuterium labeling experiments indicated that this transformation may proceed via a [1, 2-H] shift process.
- Liao, Jianhua,Zhang, Zhenming,Tang, Xiaodong,Wu, Wanqing,Guo, Wei,Jiang, Huanfeng
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p. 8903 - 8909
(2015/09/15)
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- Gold- and silver-catalyzed reactions of propargylic alcohols in the presence of protic additives
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A wide range of primary, secondary and tertiary propargylic alcohols undergo a Meyer-Schuster rearrangement to give enones at room temperature in the presence of a gold(I) catalyst and small quantities of MeOH or 4-methoxyphenylboronic acid. The syntheses of the enone natural products isoegomaketone and daphenone were achieved using this reaction as the key step. The rearrangement of primary propargylic alcohols can readily be combined in a one-pot procedure with the addition of a nucleophile to the resulting terminal enone, to give β-aryl, β-alkoxy, β-amino or β-sulfido ketones. Propargylic alcohols bearing an adjacent electron-rich aryl group can also undergo silver-catalyzed substitution of the alcohol with oxygen, nitrogen and carbon nucleophiles. This latter reaction was initially observed with a batch of gold catalyst that was probably contaminated with small quantities of silver salt.
- Pennell, Matthew N.,Turner, Peter G.,Sheppard, Tom D.
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scheme or table
p. 4748 - 4758
(2012/05/04)
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- A general procedure for the synthesis of enones via gold-catalyzed Meyer-Schuster rearrangement of propargylic alcohols at room temperature
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Meyer-Schuster rearrangements of propargylic alcohols take place readily at room temperature in toluene with 1-2 mol % PPh3AuNTf2, in the presence of 0.2 equiv of 4-methoxyphenylboronic acid or 1 equiv of methanol. Good to excellent yields of enones can be obtained from secondary and tertiary alcohols, with high selectivity for the E-alkene in most cases. A one-pot procedure for the conversion of primary propargylic alcohols into β-arylketones was also developed, via Meyer-Schuster rearrangement followed by Pd-catalayzed addition of a boronic acid.(Figure Presented)
- Pennell, Matthew N.,Unthank, Matthew G.,Turner, Peter,Sheppard, Tom D.
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supporting information; experimental part
p. 1479 - 1482
(2011/04/26)
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- Tandem catalytic triple-bond cleavage of alkyne in association with aldehyde, alkene, and water
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In this tandem reaction the carbon-carbon triple bond of an alkyne is catalytically cleaved in association with aldehyde, al-kene, and H2O under catalyst mixtures of Rh(I), 2-amino-3-picoline, primary amine, and acid. The reaction starts with chelation-assisted hydroacylation of the alkyne with an aldehyde. The retro-Mannich-type fragmentation of the resulting ,α,β-unsaturated ketimine by an amine and acid affords a ketimine and an aldimine, which is trapped by an alkene and give ketones after hydrolysis. Georg Thieme Verlag Stuttgart.
- Cha, Kyung-Mi,Jo, Eun-Ae,Jun, Chul-Ho
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scheme or table
p. 2939 - 2942
(2010/01/21)
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- Synthesis of tipranavir analogues as non-peptidic HIV protease inhibitors
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An analogue of Tipranavir was designed by replacing the dihydropyrone core with a 1,3-cyclohexanedione ring. The thio-alky1 group was used as a temporary protection group for α, β-unsaturated cyclohexane-1,3-diketone derivative, and the resulting compound was reacted with an ethyl-organometallic reagent to form the desired Michael addition product. By using this strategy, a more stable analogue of Tipranavir was synthesized and exhibited excellent HIV protease inhibition (12 nM Ki).
- Ding, Yili,Vara Prasad, Chamakura V.N.S.,Smith, Kenneth L.,Chang, Eugene,Hong, Jian,Yao, Nanhua
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scheme or table
p. 130 - 133
(2010/04/23)
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- Alcohols for the α-alkylation of methyl ketones and indirect aza-wittig reaction promoted by nickel nanoparticles
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Nickel nanoparticles have been found to activate primary alcohols used for the α-alkylation of ketones or in indirect aza-Wittig reactions. These processes involve hydrogen transfer from the alcohol to the intermediate α,β-unsaturated ketone or imine, respectively. All these reactions are carried out in the absence of any ligand, hydrogen acceptor or base under mild reaction conditions. For the first time nickel is employed as a potential alternative to noble-metal-based catalysts in both reactions. A reaction mechanism is proposed on the basis of some deuteration experiments. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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experimental part
p. 4908 - 4914
(2009/05/27)
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- A novel method of remotely triggering a cyclopropyl carbinyl to homo-allyl radical fragmentation process
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A series of model compounds were prepared in order to investigate the conditions that would favour the formation of a cyclopropyl carbinyl radical via a 1,5 hydrogen atom translocation process. The models varied in the degree of unsaturation adjacent to the cyclopropyl carbinyl position and it was found that the 1,5 hydrogen atom radical translocation process was favoured only when alternative cyclisation pathways were not possible.
- Penkett, Clive S.,Lane, Richard
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p. 112 - 114
(2008/02/02)
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- The α-alkylation of methyl ketones with primary alcohols promoted by nickel nanoparticles under mild and ligandless conditions
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Nickel nanoparticles have been found to promote the α-alkylation of ketones with primary alcohols in the absence of any added ligand or base, under mild reaction conditions. Georg Thieme Verlag Stuttgart.
- Alonso, Francisco,Riente, Paola,Yus, Miguel
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p. 1877 - 1880
(2008/02/10)
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- Design, synthesis, and biological evaluation of novel 4-hydroxypyrone derivatives as HIV-1 protease inhibitors
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Twenty-four 4-hydroxypyrone derivatives were synthesized with a facile synthetic method to develop novel HIV protease inhibitors. Most of them were shown to display good antiviral activities in SIV-infected CEM cells. The introduction of α-naphthylmethyl group to C-6 of 5,6-dihydropyran-2-ones led to an effective antiviral compound that showed an EC50 value at 1.7 μM with a therapeutic index of 46.
- Sun, Chun-Lai,Pang, Rui-Fang,Zhang, Hang,Yang, Ming
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p. 3257 - 3262
(2007/10/03)
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- Process for separating zinc salts from zinc alcoholates or zinc amides containing non-aqueous synthesis solvents
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A process for the removal of zinc from organic solutions containing zinc alcoholates or zinc amides comprises addition of an alkylating, arylating, acylating or silylating agent in the presence of a precipitating agent having at least two nitrogen donors followed by separation of the precipitated solid.
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Page/Page column 9-12
(2010/02/06)
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- Synthesis and antitumor activity of 4-hydroxycoumarin derivatives
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A series of 4-hydroxycoumarin derivatives was prepared and evaluated for antitumor activity against five human tumor cell lines. A series of 4-hydroxycoumarin derivatives was prepared and evaluated for antitumor activity. The key fragments were 2a-c, 5c, 12b, 13b, 17, and 18 which were prepared via dianion ring cyclization, Friedel-Crafts acylation, and Reformatsky reaction. Compound 20b showed the most potent antitumor activity among the total 12 derivatives and compounds 19a and 19b exhibited efficacy comparable to etoposide in vitro antitumor activity.
- Jung, Jae-Chul,Lee, Ji-Ho,Oh, Seikwan,Lee, Jae-Gon,Park, Oee-Sook
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p. 5527 - 5531
(2007/10/03)
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- Heck reactions of aryl bromides with alk-1-en-3-ol derivatives catalysed by a tetraphosphine/palladium complex
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cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/ [PdCl(C3H5)]2 efficiently catalyses the Heck reaction of alk-1-en-3-ol with a variety of aryl bromides. In the presence of hex-1-en-3-ol or oct-1-en-3-ol, the β-arylated carbonyl compounds were selectively obtained. Linalool and 2-methylbut-3-en-2-ol led to the corresponding 1-arylalk-1-en-3-ol derivatives. Turnover numbers up to 69,000 can be obtained for this reaction. A minor electronic effect of the substituents of the aryl bromide was observed. Similar reaction rates were observed in the presence of activated aryl bromides such as bromoacetophenone and deactivated aryl bromides such as bromoanisole.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 5633 - 5636
(2007/10/03)
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- Production method of (R) -3 hydroxy-3- (2-phenylethyl) hexanoic acid and intermediate thereof
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The present invention relates to a production method of (R)-3-hydroxy-3-(2-phenylethyl)hexanoic acid which comprises optical resolution of racemic 3-hydroxy-3-(2-phenylethyl)hexanoic acid with an optically active amine of the formula (VIII) 1wherein R2 is 3,4-dimethoxyphenyl or 2-chlorophenyl. According to the present invention, (R)-3-hydroxy-3-(2-phenylethyl)hexanoic acid useful as a starting material of a pharmaceutical agent can be efficiently produced with a high optical purity and a relatively high total yield.
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- A hydroacylation-triggered carbon-carbon triple bond cleavage in alkynes via retro-Mannich type fragmentation
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The carbon-carbon triple bond in alkyne is cleaved via hydroacylation followed by retro-Mannich type fragmentation in the presence of aldehyde, which triggers a successive C-C bond cleavage. Copyright
- Lee, Dae-Yon,Hong, Boo-Sun,Cho, Eung-Goo,Lee, Hyuk,Jun, Chul-Ho
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p. 6372 - 6373
(2007/10/03)
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- Process for the preparation of hydroxy and amino compounds
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A process for the preparation of hydroxy and amino compounds, in which, in a first step, an aldehyde, ketone or imine is reacted in a Reformatsky reaction with a reactive halogen compound and zinc, in carboxylic esters as solvents, the reactive halogen compound being brought into contact with the zinc at the same time as or after contact with the aldehyde, ketone or imine, and in a second step, the reaction product of the first step is hydrolyzed.
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- Process for the preparation of carbonyl compounds by cleavage of hydroxycarboxylic acids
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The invention relates to a process for the preparation of a carbonyl compound of the general formula (1) R1R2C═O??(1), in which a β-hydroxycarboxylic acid or its salt of the general formula (2) R1R2C(OH)—CR3R4—COOM??(2) is cleaved in the presence of a Br?nstedt base which is selected from hydroxides, alkanolates, oxides, amides and hydrides of the alkali metals and alkaline earth metals, and in the presence of a hydroxyl-free solvent, R1, R2, R3, R4 and M having the meanings from claim 1.
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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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- Barbier-type reactions of nitriles and alkyl iodides mediated by samarium(II) iodide in the presence of catalytic nickel(II) iodide
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The samarium(II) iodide-mediated intermolecular Barbier-type reactions of nitriles and alkyl iodides have been investigated. In the presence of a catalytic amount of nickel(II) iodide, the reaction proceeded smoothly to provide the corresponding ketones. Amides also reacted to give ketones under the same Barbier-type conditions. (C) 2000 Elsevier Science Ltd.
- Kang, Han-Young,Song, Sang-Eun
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p. 937 - 939
(2007/10/03)
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- Highly Regioselective Monoalkylation of Ketones via Manganese Enolates. Prepared from Lithium Enolates
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Li-enolates are readily converted to Mn-enolates by treatment with manganese halides.In THF, the reaction is easily and economically performed with manganese chloride at room temperature.Mn-enolates can then be regioselectively monoalkylated in good yields.The formation of di and polyalkylated products is never observed (1percent).
- Cahiez, Gerard,Chau, Khi,Clery, Patrick
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p. 3069 - 3072
(2007/10/02)
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- ISOXAZOLINE OXIDATION. AN EFFICIENT METHOD FOR THE PREPARATION OF α,β-UNSATURATED CARBONYL COMPOUNDS
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MCPBA peracid oxidation of Δ4-isoxazolines derived from the dipolar cycloaddition reaction of nitrones with acetylenes or allenes produces α,β-unsaturated ketones in excellent yield.
- Padwa, Albert,Kline, Donald N.,Perumattam, John
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p. 913 - 916
(2007/10/02)
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- REDUCTION OF BENZYLIDENEACETONE DERIVATIVES WITH Pd/SiO2-AlPO4 AS CATALYST AND CYCLOHEXENE AS HYDROGEN DONOR
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The hydrogen transfer reduction of benzylidenacetone derivatives p-X-C6H4-CH=CH-CO-R (X=-OCH3, H; R=C6H5, alkyl, OR, OH) using cyclohexene as hydrogen donor has been studied.The selective reduction of the C=C bond is observed and the effects of the nature of X and R, solvent, catalyst, and reaction temperature on the initial reaction rate are analyzed.In all cases, and for any substrate or catalyst, the reaction is firts-order with respect to the hydrogen donor and acceptor.
- Alba, A.,Aramendia, A.,Borau, V.,Garcia-Raso, A.,Jimenez, C.,Marinas, J. M.
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p. 917 - 921
(2007/10/02)
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