- One-step solvent-free aerobic oxidation of aliphatic alcohols to esters using a tandem Sc-Ru?MOF catalyst
-
Esters are an important class of chemicals in industry. Traditionally, ester production is a multi-step process involving the use of corrosive acids or acid derivatives (e.g. acid chloride, anhydride, etc.). Therefore, the development of a green synthetic protocol is highly desirable. This work reports the development of a metal-organic framework (MOF) supported tandem catalyst that can achieve direct alcohol to ester conversion (DAEC) using oxygen as the sole oxidizing agent under strictly solvent-free conditions. By incorporating Ru nanoparticles (NPs) along with a homogeneous Lewis acid catalyst, scandium triflate, into the nanocavities of a Zr MOF, MOF-808, the compound catalyst, Sc-Ru?MOF-808, can achieve aliphatic alcohol conversion up to 92% with ester selectivity up to 91%. A mechanistic study reveals a unique “via acetal” pathway in which the alcohol is first oxidized on Ru NPs and rapidly converted to an acetal on Sc(iii) sites. Then, the acetal slowly decomposes to release an aldehyde in a controlled manner for subsequent oxidation and esterification to the ester product. To the best of our knowledge, this is the first example of DAEC of aliphatic alcohols under solvent-free conditions with high conversion and ester selectivity.
- Feng, Tingkai,Li, Conger,Li, Tao,Zhang, Songwei
-
supporting information
p. 1474 - 1480
(2022/03/08)
-
- Mild and Selective Rhodium-Catalyzed Transfer Hydrogenation of Functionalized Arenes
-
Diboron-mediated rhodium-catalyzed transfer hydrogenation of functionalized arenes is reported. In addition to good functional group tolerance, the reaction features operational simplicity and controllable chemoselectivity. The general applicability of this procedure is demonstrated by the selective hydrogenation of a range of arenes, including functionalized benzenes, biphenyls, and polyaromatics.
- Wang, Yuhan,Chang, Zhiqian,Hu, Yan,Lin, Xiao,Dou, Xiaowei
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supporting information
p. 1910 - 1914
(2021/03/08)
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- Method for preparing carboxylic acid by one-pot method
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The invention discloses a method for preparing carboxylic acid by a one-pot method, which comprises the steps of carrying out a Corey-Fuchs process on 1,1-dibromo olefin under the action of n-butyllithium, reacting with isopropanol pinacol borate, quenching with hydrogen chloride, oxidizing with an oxidant, separating and purifying to obtain carboxylic acid. The method disclosed by the invention is a one-pot preparation method, is simple and convenient to operate, does not need to use metal catalysis, uses cheap and easily available reagents for reaction, is green and environment-friendly, hasmild reaction conditions and wide substrate applicability, and provides a new way for rapidly preparing a series of carboxylic acids containing different functional groups.
- -
-
Paragraph 0076-0080
(2021/01/29)
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- Pd-Catalyzed Highly Chemo- And Regioselective Hydrocarboxylation of Terminal Alkyl Olefins with Formic Acid
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An efficient Pd-catalyzed hydrocarboxylation of alkenes with HCOOH is described. A wide variety of linear carboxylic acids bearing various functional groups can be obtained with excellent chemo- and regioselectivities under mild reaction conditions. The reaction process is operationally simple and requires no handling of toxic CO.
- Ren, Wenlong,Chu, Jianxiao,Sun, Fei,Shi, Yian
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supporting information
p. 5967 - 5970
(2019/08/26)
-
- Synthetic method of terminal carboxylic acid
-
The invention discloses a synthetic method of a terminal carboxylic acid. The synthetic method is characterized by comprising the steps of adding an olefin represented by a formula (3) shown in the description, formic acid, acetic anhydride, Pd(OAc)2 and a monophosphorus ligand TFPP into an organic solvent in a proportion, carrying out hydrogen carbonylation reaction on the olefin represented by the formula (3) shown in the description, formic acid and acetic anhydride at 80-90 DEG C for 48h-72h under the catalysis of the metal palladium salt Pd(OAc)2 and the monophosphorus ligand TFPP so as to obtain the terminal carboxylic acid represented by a formula shown in the description, and separating a target product, namely the terminal carboxylic acid after the reaction is finished, wherein olefin represented by the formula (3) is selected from cycloolefins, or linear olefins of which the R1 is electron donating groups. By virtue of the method disclosed by the invention, corresponding terminal carboxylic acid and a derivative thereof can be prepared through the reaction under mild conditions of low temperature and no high pressure; and the steps of the synthetic method are simple and convenient, the operation is convenient, the yield is high, the energy source can be greatly saved, and the synthetic efficiency can be greatly improved.
- -
-
Paragraph 0115-0118
(2019/11/21)
-
- Method for synthesizing cyclohexanecarboxylic acid by catalyzing hydrogenation of benzene rings through rubidium-gallium-loaded catalytic material
-
The invention relates to the fine chemical engineering field and particularly relates to a method for synthesizing cyclohexanecarboxylic acid by catalyzing hydrogenation of benzene rings through a rubidium-gallium-loaded catalytic material. According to the method, aromatic ring carboxylic acid is catalyzed by virtue of the rubidium-gallium-loaded catalytic material in deionized water and generates selective addition reaction with hydrogen at a low temperature and a relatively low pressure so as to generate cyclohexanecarboxylic acid; the reaction temperature is low, the reaction pressure is lower than that in the prior art, no organic solvent is adopted, the side reactions are few, and the product is conveniently purified, and the method is suitable for industrial production; and the prepared rubidium-gallium-loaded catalytic material can be recycled, is high in catalytic activity and strong in selectivity and is a very promising novel catalytic material.
- -
-
Paragraph 0024
(2019/01/24)
-
- Polysilane-Immobilized Rh-Pt Bimetallic Nanoparticles as Powerful Arene Hydrogenation Catalysts: Synthesis, Reactions under Batch and Flow Conditions and Reaction Mechanism
-
Hydrogenation of arenes is an important reaction not only for hydrogen storage and transport but also for the synthesis of functional molecules such as pharmaceuticals and biologically active compounds. Here, we describe the development of heterogeneous Rh-Pt bimetallic nanoparticle catalysts for the hydrogenation of arenes with inexpensive polysilane as support. The catalysts could be used in both batch and continuous-flow systems with high performance under mild conditions and showed wide substrate generality. In the continuous-flow system, the product could be obtained by simply passing the substrate and 1 atm H2 through a column packed with the catalyst. Remarkably, much higher catalytic performance was observed in the flow system than in the batch system, and extremely strong durability under continuous-flow conditions was demonstrated (>50 days continuous run; turnover number >3.4 × 105). Furthermore, details of the reaction mechanisms and the origin of different kinetics in batch and flow were studied, and the obtained knowledge was applied to develop completely selective arene hydrogenation of compounds containing two aromatic rings toward the synthesis of an active pharmaceutical ingredient.
- Miyamura, Hiroyuki,Suzuki, Aya,Yasukawa, Tomohiro,Kobayashi, Shu
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supporting information
p. 11325 - 11334
(2018/09/06)
-
- Selective hydrogenation of benzoic acid to cyclohexane carboxylic acid over microwave-activated Ni/carbon catalysts
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High yields of cyclohexane carboxylic acids were obtained by direct hydrogenation of aromatic carboxylic acids over different Ni/carbon catalysts having distinctive surface properties. The catalysts were characterized by SEM, TEM, H2-TPR and N2 adsorption isotherms for the determination of BET surface area and porosity. The hydrogenation reaction was carried out in batch pressure reactor in gas-liquid phase at 200 °C. High selectivity (100%) of cyclohexane carboxylic acids at 86.2 mol% conversion of benzoic acid was achieved over microwave-activated biochar supported non-precious metal Ni catalyst. The 10%Ni/CSC-b catalyst has been investigated for hydrogenation of benzoic acid to cyclohexane carboxylic acids and shown little deactivation in stability test. The effects of Ni loading, high dispersion of Ni species, appropriate power of microwave heating and strong interaction of Ni species with carbon are of benefit to the reaction.
- Lu,Shen,He,Jing,Tao,Hu,Nie,Zhou,Xia
-
-
- CATALYTIC CARBOXYLATION OF ACTIVATED ALKANES AND/OR OLEFINS
-
The present invention relates to a method of reacting starting materials with an activating group, namely alkanes carrying a leaving group and/or olefins, with carbon dioxide under transition metal catalysis to give carboxyl group-containing products. It is a special feature of the method of the present invention that the carboxylation predominantly takes place at a preferred position of the molecule irrespective of the position of the activating group. The carboxylation position is either an aliphatic terminus of the molecule or it is a carbon atom adjacent to a carbon carrying an electron withdrawing group. The course of the reaction can be controlled by appropriately choosing the reaction conditions to yield the desired regioisomer.
- -
-
Page/Page column 57; 62; 63; 65; 66
(2018/02/28)
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- Silver-Catalyzed Dehydrogenative Synthesis of Carboxylic Acids from Primary Alcohols
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A simple silver-catalyzed protocol has been developed for the acceptorless dehydrogenation of primary alcohols into carboxylic acids and hydrogen gas. The procedure uses 2.5 % Ag2CO3 and 2.5–3 equiv of KOH in refluxing mesitylene to afford the potassium carboxylate which is then converted into the acid with HCl. The reaction can be applied to a variety of benzylic and aliphatic primary alcohols with alkyl and ether substituents, and in some cases halide, olefin, and ester functionalities are also compatible with the reaction conditions. The dehydrogenation is believed to be catalyzed by silver nanoparticles that are formed in situ under the reaction conditions.
- Ghalehshahi, Hajar Golshadi,Madsen, Robert
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p. 11920 - 11926
(2017/09/07)
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- Remote carboxylation of halogenated aliphatic hydrocarbons with carbon dioxide
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Catalytic carbon-carbon bond formation has enabled the streamlining of synthetic routes when assembling complex molecules. It is particularly important when incorporating saturated hydrocarbons, which are common motifs in petrochemicals and biologically relevant molecules. However, cross-coupling methods that involve alkyl electrophiles result in catalytic bond formation only at specific and previously functionalized sites. Here we describe a catalytic method that is capable of promoting carboxylation reactions at remote and unfunctionalized aliphatic sites with carbon dioxide at atmospheric pressure. The reaction occurs via selective migration of the catalyst along the hydrocarbon side-chain with excellent regio- and chemoselectivity, representing a remarkable reactivity relay when compared with classical cross-coupling reactions. Our results demonstrate that site-selectivity can be switched and controlled, enabling the functionalization of less-reactive positions in the presence of a priori more reactive ones. Furthermore, we show that raw materials obtained in bulk from petroleum processing, such as alkanes and unrefined mixtures of olefins, can be used as substrates. This offers an opportunity to integrate a catalytic platform en route to valuable fatty acids by transforming petroleum-derived feedstocks directly.
- Juliá-Hernández, Francisco,Moragas, Toni,Cornella, Josep,Martin, Ruben
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- Bridging C?H Activation: Mild and Versatile Cleavage of the 8-Aminoquinoline Directing Group
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8-Aminoquinoline has emerged as one of the most powerful bidentate directing groups in history of C?H activation within the last decade. However, cleavage of its robust amide bond has shown to be challenging in several cases, thus jeopardizing the general synthetic utility of the method. To overcome this limitation, we herein report a simple oxidative deprotection protocol. This transformation rapidly converts the robust amide to a labile imide, allowing subsequent cleavage in a simple one-pot fashion to rapidly access carboxylic acids or amides as final products.
- Berger, Martin,Chauhan, Rajan,Rodrigues, Catarina A. B.,Maulide, Nuno
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supporting information
p. 16805 - 16808
(2016/11/16)
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- Selective hydrogenation of aromatic carboxylic acids over basic N-doped mesoporous carbon supported palladium catalysts
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Mesoporous carbon nitride (MCN) has been prepared through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard-templating approach. The obtained MCN possesses high surface area (166.3 m2/g), average pore size of 9.2 nm and high N content (up to 18.5 wt%). The negative charge and the basicity on MCN surface are originated from its rich carbon nitride heterocycles, which notably improves the surface hydrophilicity and the adsorption of acidic molecules. Furthermore, MCN can be adopted as the proper support for highly dispersed Pd NPs with well-controlled size distribution. Compared with microporous N-doped active carbon with low N-content, the MCN-supported Pd catalyst shows an enhanced activity in water phase for the selective ring hydrogenation of benzoic acid, benzamide and phenol, in which 11.3 times higher activity in comparison to undoped catalyst is achieved. Wide characterizations reveal that big pore size, selective adsorption for acid substrate and strong interaction between N and Pd may lead to the high activity of Pd/MCN.
- Jiang, Hezhan,Yu, Xiaolong,Nie, Renfeng,Lu, Xinhuan,Zhou, Dan,Xia, Qinghua
-
-
- A NiPdB-PEG(800) amorphous alloy catalyst for the chemoselective hydrogenation of electron-deficient aromatic substrates
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A new Pd and polyethylene glycol 800 [PEG(800)]-modified NiB [NiPdB-PEG(800)] amorphous alloy catalyst was prepared, which demonstrated excellent activities, similar to those of noble metal catalysts, in the chemoselective hydrogenation of a series of electron-deficient aromatic substrates in water. The addition of small amounts of Pd to NiB markedly improved its activity. The Pd not only benefits the dispersion of active species but also contributes to the activity of the catalyst. The accompanying agglomeration can be inhibited with the further addition of PEG(800), which results in the largest surface area, the smallest particle size, and the greatest number of active species, resulting in optimum H2- chemisorption and accounting for its highest activity. The key factors determining the main reaction products depend not only on the structures of the substrates but also on the character of the solvents. Water is found to be the most effective solvent for most of the substrates. Disperse and be active! A Pd and polyethylene glycol 800 [PEG(800)]-modified NiB [NiPdB-PEG(800)] amorphous alloy catalyst demonstrates excellent activities, similar to those of noble metal catalysts, in the chemoselective hydrogenation of a series of electron-deficient aromatic substrates in water. The addition of Pd benefits the dispersion of active species and contributes to the activity of the catalyst. Copyright
- Bai, Guoyi,Zhao, Zhen,Dong, Huixian,Niu, Libo,Wang, Yalong,Chen, Qingzhi
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p. 655 - 662
(2014/03/21)
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- A chemoselective oxidation of monosubstituted ethylene glycol: Facile synthesis of optically active α-hydroxy acids
-
A mild and efficient method for the synthesis of optically active α-hydroxy acids through chemoselective oxidation of monosubstituted ethylene glycols using the TEMPO-NaOCl reagent system is described. It is evident from our studies that the solvent, pH and reaction temperature are very crucial for the success of this oxidation. The versatility of this method has been demonstrated with a variety of aliphatic, aromatic and carbohydrate substrates bearing various functional groups. the Partner Organisations 2014.
- Chinthapally, Kiran,Baskaran, Sundarababu
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p. 4305 - 4309
(2014/06/23)
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- Unexpected dehomologation of primary alcohols to one-carbon shorter carboxylic acids using o-iodoxybenzoic acid (IBX)
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A novel and efficient transformation of primary alcohols to one-carbon shorter carboxylic acids using IBX is reported. Mechanistic studies revealed that the combination of IBX and molecular iodine produces a different active hypervalent iodine species.
- Xu, Shu,Itto, Kaori,Satoh, Masahide,Arimoto, Hirokazu
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p. 2758 - 2761
(2014/03/21)
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- Carbon dioxide as a C1 building block for the formation of carboxylic acids by formal catalytic hydrocarboxylation
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A happy marriage of two processes: An effective catalytic system was identified for the direct synthesis of carboxylic acids from non-activated olefins or alcohols, CO2, and H2. Detailed analysis together with labeling studies indicated that the overall hydrocarboxylation of simple olefins results from a combination of the reverse water-gas shift (rWGS) reaction and a hydroxycarbonylation step, each promoted by a rhodium catalyst (see scheme). Copyright
- Ostapowicz, Thomas G.,Schmitz, Marc,Krystof, Monika,Klankermayer, Juergen,Leitner, Walter
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p. 12119 - 12123
(2013/12/04)
-
- Synthesis of α-CF3-substituted carbonyl compounds with relative and absolute stereocontrol using electrophilic CF3-transfer reagents
-
Evans-type chiral lithium imide enolates undergo diastereoselective α-trifluoromethylation with a hypervalent iodine-CF3 reagent with up to 91% combined isolated yield and 97:3 dr. The resulting isolated diastereopure products can be further transformed into valuable products without racemization.
- Matousek, Vaclav,Togni, Antonio,Bizet, Vincent,Cahard, Dominique
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supporting information; experimental part
p. 5762 - 5765
(2012/01/06)
-
- Novel aerobic oxidation of primary sulfones to carboxylic acids
-
Primary alkyl aryl sulfones are converted to the corresponding carboxylic acids in fair to excellent yield through double deprotonation and exposure to atmospheric oxygen. The methodology allows for the convenient synthesis of 13C labeled carboxylic acids.
- Bonaparte, Amy C.,Betush, Matthew P.,Panseri, Bettina M.,Mastarone, Daniel J.,Murphy, Ryan K.,Murphree, S. Shaun
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p. 1447 - 1449
(2011/05/08)
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- Aqueous phase hydrogenation of substituted phenyls over carbon nanofibre and activated carbon supported Pd
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The hydrogenation of aromatic acids and other substituted phenyls has been studied for two palladium-based catalysts; one supported on carbon nanofibres (CNFs) and the other on a steam-activated carbon. The reactions were conducted in both aqueous solution and aprotic organic solvents. The major product over both catalysts was the same irrespective of the substrate indicating that support characteristics and Pd dispersion play at most only a minor role in defining the reaction pathway. The key factor in determining the major reaction product resulting from either preferential hydrogenation of the aromatic ring, or reaction of the external functional group, was the extent to which the external group interacted with water molecules which acted in some cases to protect the external function from interaction with the metal surface and induced selective reduction of the aromatic ring.
- Anderson,Athawale,Imrie,McKenna,McCue,Molyneux,Power,Shand,Wells
-
experimental part
p. 9 - 15
(2010/06/12)
-
- General and practical conversion of aldehydes to homologated carboxylic acids
-
(Chemical Equation Presented) The reaction of aldehydes with trichloromethide followed by sodium borohydride or sodium phenylseleno(triethyl) borate under basic conditions affords homologated carboxylic acids in high yields. This operationally simple procedure provides a practical, efficient alternative to other homologation protocols. The approach is compatible with sensitive aldehydes including enals and enolizable aldehydes. It also offers convenient access to α-monodeuterated carboxylic acids.
- Cafiero, Lauren R.,Snowden, Timothy S.
-
supporting information; experimental part
p. 3853 - 3856
(2009/07/01)
-
- Electrocatalytic carboxylation of aliphatic halides at silver cathode in acetonitrile
-
A simple and efficient electrocarboxylation reaction of aliphatic halides has been developed using silver as cathode, magnesium as anode and CH3CN saturated CO2 as solvent in an undivided cell. The influence of some key factors (such as the nature of electrode materials, supporting electrolytes and temperature) on this reaction was investigated. Under the optimized condition, the corresponding carboxylic acids were obtained in moderate to good yields (22-89%). The electrochemical behaviour was studied at different electrodes (Ag, Cu, Ni and Ti) by cyclic voltammetry, which showed significant electrocatalytic effect of the silver electrode towards the reductive carboxylation of aliphatic halides.
- Niu, Dong-Fang,Xiao, Li-Ping,Zhang, Ai-Jian,Zhang, Gui-Rong,Tan, Qi-Yun,Lu, Jia-Xing
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p. 10517 - 10520
(2008/12/23)
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- Indium-mediated chemoselective deprotection and demonochlorination of 2,2,2-trichloroethyl esters
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On treatment with indium metal, the 2,2,2-trichloroethyl carboxylates smoothly undergo deprotection to carboxylic acids and reductive demonochlorination to 2,2-dichloroethyl esters, sharply depending on their structures.
- Mineno, Tomoko,Kansui, Hisao,Kunieda, Takehisa
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p. 5027 - 5030
(2008/02/10)
-
- Highly efficient oxidation of alcohols to carbonyl compounds in the presence of molecular oxygen using a novel heterogeneous ruthenium catalyst
-
A ruthenium cation combined with microcrystals of cobalt hydroxide and cerium oxide acted as a highly efficient heterogeneous catalyst for the oxidation of various types of alcohols to carbonyl compounds under atmospheric pressure of molecular oxygen at 60°C. Especially, primary aliphatic alcohols could be oxidized to afford the carboxylic acids in high yields.
- Ji, Hongbing,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 7179 - 7183
(2007/10/03)
-
- Ligand exchange reaction of sulfoxides in organic synthesis: A versatile procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides
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A novel two-step procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides is described. Methylesters are reacted with lithium carbanion of chloromethyl phenyl sulfoxide to give α-chloro α-sulfinyl ketones in 70 to 90% yields. Potassium enolate of the α-chloro α-sulfinyl ketone was treated with tert-butyllithium at -78°C to give alkynolate via alkylidene carbenoid. This intermediate was treated with alcohols, thioles, 5% aqueous NaOH, and amine hydrochlorides to afford one-carbon homologated esters, thioesters, carboxylic acids and amides, respectively, in good to excellent yields.
- Satoh, Tsuyoshi,Unno, Hideaki,Mizu, Yasuhiro,Hayashi, Yasumasa
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p. 7843 - 7854
(2007/10/03)
-
- Unusual products from dirhodium tetraacetylate-catalyzed decomposition of diazoacetylcycloalkanes
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Rh2(OAc)4-assisted decompositions of diazoacetylcycloalkanes are shown to yield cycloalkylacetic acids (Wolff rearrangement), unexpected cycloalkylcarboxylic acids and bicyclic ketones (intramolecular C-H bond insertion). Rh2(OCOF3)4-promoted reactions, on the other hand, have furnished bicyclic ketones and ketene dimers.
- Ceccherelli, Paolo,Curini, Massimo,Marcotullio, Maria Carla,Pisani, Emanuela,Rosati, Ornelio,Wenkert, Ernest
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p. 8501 - 8506
(2007/10/03)
-
- Diastereoselectivity in the SE2″ reaction of chiral pentadienylsilanes: A test for the relative importance of steric and electronic effects
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The homochiral pentadienylsilanes (3Z,5E)-(hepta-3,5-dien-2-yl)dimethyl(phenyl)silane 9, (3Z,5E)-(hepta-3,5-dien-2-yl)trimethylsilane 13, (4Z,6E)-(2-methylocta-4,6-dien-3-yl)dimethyl(phenyl)silane 14 and (4Z,6E)-(2-methylocta-4,6-dien-3-yl)trimethylsilane 17 undergo Lewis acid catalysed reactions with isobutyraldehyde and its dimethyl acetal stereospecifically anti with surprisingly high levels of stereoselectivity, ca. 90:10. The pentadienylsilanes (3Z)-hexa-3,5-dien-2-yldimethyl(phenyl)silane 20aa, (4Z)-(2-methylhepta-4,6-dien-3-yl)dimethyl(phenyl)silane 20ab, (3Z)-(hexa-3,5-dien-2-yl)-trimethylsilane 20ba and (2Z)-(1-phenylpenta-2,4-dienyl)trimethylsilane 20bc undergo dipolar cycloadditions to 2,2-dimethylpropanenitrile oxide regioselectively at the terminal double bond and stereoselectively anti to the silyl group to a somewhat lower extent, ca. 70:30. The pentadienylsilane (3Z,5E)-(6-cyclohexylhexa-3,5-dien-2-yl)trimethylsilane 25 undergoes deuteriodesilylation stereospecifically anti to a lower extent still, ca. 55:45. The pentadienylsilane (3Z,5E)-(8-methyl-8-methoxyethoxymethoxynona-3,5-dien-2-yl)trimethylsilane 34 undergoes an intramolecular reaction stereospecifically anti again to the extent of about 60:40, whereas the reaction of the corresponding allylsilane (3Z)-(6-methyl-6-methoxyethoxymethoxyhept-3-en-2-yl)trimethylsilane 32 is essentially completely anti. These results show that SE2″ reactions can be highly stereoselective in the anti sense, that the high level is probably best accounted for by the steric effect of the silyl group, and that when the steric effect is minimised, the stereospecificity is low, but still measurable. The pentadienylsilanes were prepared by aldol reactions between β-silyl esters and the appropriate α,β-unsaturated aldehyde, followed by decarboxylative elimination. The products of the SE2″ reactions were identified and their stereochemistry determined by comparison with authentic materials or by degradation and synthesis, using chiral auxiliaries to determine the enantiomeric purity. The products of two of the dipolar cycloadditions were identified by degradation and stereospecific vinylogous Peterson elimination, but the vinylogous Peterson elimination taking place with (1RS,2Z,4SR,6SA)-(4,6-dihydroxy-7,7-dimethyl-1-phenyloct-2-enyl)trimethylsilane 67bc and its (1SR) diastereoisomer 68bc was not stereospecific, giving (5E,7E)-2,2-dimethyl-8-phenylocta-5,7-dien-3-ol 73 from both isomers. The stereochemistries of all the reactions are summarised.
- Fleming, Ian,Jones, Graeme R.,Kindon, Nicholas D.,Landais, Yannick,Leslie, Colin P.,Morgan, Ian T.,Peukert, Stefan,Sarkar, Achintya K.
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p. 1171 - 1196
(2007/10/03)
-
- The Invention of Radical Reactions. XXXIII Homologation Reactions of Carboxylic Acids by Radical Chain Chemistry
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Various carbon radicals can be generated from carboxylic acids via the corresponding Barton esters.These radicals can be used for the synthesis of longer chain homologues of the original acids.
- Barton, Derek H. R.,Chern, Ching-Yuh,Jaszberenyi, Joseph Cs.
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p. 407 - 426
(2007/10/02)
-
- Shape and aggregating tendency. The aggregating behavior of eight esters of eight-carbon carboxylic acids
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The aggregating tendencies of eight p-nitrophenyl esters of eight-carbon carboxylic acids (1-8) and two O-octyl phosphonates (10, 11) have been evaluated by measuring their critical aggregate concentrations (CAgG's). Results show that (1) branching reduce
- Jiang, Xi-Kui,Ji, Guo-Zhen,Tu, Bo,Zhang, Xin-Yu,Shi, Ji-Liang,Chen, Xin
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p. 12679 - 12682
(2007/10/03)
-
- Electron transfer induced reductive cleavage of γ-lactones to carboxylic acids by sodium-hexamethylphosphoric triamide (HMPA)
-
Sodium-hexamethylphosphoric triamide (HMPA) mediated electron transfer induced reductive cleavage of 1 -> 3 and 1 -> 2 γ-lactones fused in cyclohexane ring gives the corresponding carboxylic acids in good yields.
- Mukhopadhyaya, Jayanta K.,Mukhopadhyay, Chhanda,Ghatak, Usha Ranjan
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p. 132 - 136
(2007/10/02)
-
- HETEROCUMULENES IN ACYLATION REACTIONS II. REACTIVITY OF ALKYL-SUBSTITUTED KETENES IN SPONTANEOUS HYDROLYSIS REACTIONS
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The structures and electronic states of six ketenes were investigated by the semiempirical MNDO, MINDO/3, and AM1 quantum-chemical methods.The kinetics of the spontaneous hydrolysis of mono- and dialkylsubstituted ketenes in water and water-acetonitrile mixtures at 20 deg C were studied.The induction and steric effects of the substituents on the process rate were evaluated quantitatively in terms of a ρ? analysis.An increase in the number, length, and branching of the hydrocarbon substituents at the terminal carbon atom of the ketenes leads to a large decrease in the hydrolysis rate.The results of the calculations were compared with experimental data.Possible alternatives for the mechanism of the process are discussed.
- Lyashchuk, S. N.,Skrypnik, Yu. G.
-
-
- Homologation of carboxylic acids by improved methods based on radical chain chemistry of acyl derivatives of N-hydroxy-2-thiopyridone
-
Reaction of substituted terminal olefins with carbon radicals generated carboxylic acids gives adducts that can be transformed to one carbon atom longer homo-acids in high overall yield. With 6b yields are very good and the conditions of hydrolysis exceptionally mild.
- Barton, Derek H. R.,Chern, Ching-Yuh,Jaszberenyi, Joseph Cs.
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p. 5013 - 5016
(2007/10/02)
-
- Pd-Catalyzed Regio- and Stereo-selective Carboxylation of Cycloalkanes with CO
-
The reactions of cycloalkanes with CO via the C-H bond activation by Pd(OAc)2 catalyst have been found to proceed regio- and stereo-selectively to give corresponding carboxylic acids.The reactivity of C-H bonds of cycloalkanes decreases in the order: tert- > sec- > prim-carbon, and the stereochemistry of the substitutents on the main products is all equatorial.
- Satoh, Ko-ichi,Watanabe, Jun,Takaki, Ken,Fujiwara, Yuzo
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p. 1433 - 1436
(2007/10/02)
-
- HOMOLOGATION OF ACIDS via CARBON RADICALS GENERATED FROM THE ACYL DERIVATIVES OF N-HYDROXY-2-THIOPYRIDONE. (THE TWO-CARBON PROBLEM).
-
Reaction of suitable substituted olefins with carbon radicals generated from the acyl derivatives of N-hydroxy-2-thiopyridone results in the formation of precursors for the corresponding homo-acids.These compounds can then be transformed to the desired end-products in high yield under mild conditions.
- Barton, Derek H. R.,Chern, Ching-Yuh,Jaszberenyi, Joseph Cs.
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p. 3309 - 3312
(2007/10/02)
-
- Selective Oxidation of Alcohols and Aldehydes with Hydrogen Peroxide Catalyzed by Methyltrioctylammonium Tetrakis(oxodiperoxotungsto)phosphate(3-) under Two-Phase Conditions
-
The use of methyltrioctylammonium tetrakis(oxodiperoxotungsto)phosphate(3-) (1c) in combination with hydrogen peroxide as the primary oxidant in an aqueous/organic biphase system provides a cheap, efficient, and versatile catalytic method for alcohol and aldehyde oxidation.By this method, a variety of water-insoluble primary and secondary alcohols and aldehydes were oxidized to carboxylic acids and ketones in good yields under mild conditions and after relatively short reaction times.
- Venturello, Carlo,Gambaro, Mario
-
p. 5924 - 5931
(2007/10/02)
-
- Direct Synthesis of Carboxylic Acids from Organoboranes
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Direct Synthesis of carboxylic acids through a two carbon atom homologation from organoboranes has been achieved, by the reaction with the dianion of phenoxyacetic acid.It is now possible to synthesize alkanoic, alkenoic, or alkynoic acids, from the corresponding alkenes, dienes, or enynes, respectively, via hydroboration.The reaction is tolerant of various functional groups present in alkenes, thus giving the corresponding carboxylic acids with chloro, sulfide, ether, acetal, and thioacetal functionalities in good yields.
- Hara, Shoji,Kishimura, Kotaro,Suzuki, Akira,Dhillon, Ranjit S.
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p. 6356 - 6360
(2007/10/02)
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- Phosphodiesterase inhibitors.
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A compound of formula (I), or a pharmaceutically acceptable salt thereof: in which, R1 is hydrogen, C1-6 alkyl or CH2OR6; R2 is hydrogen or C1-6 alkyl; R3 is hydrogen or C1-6 alkyl; each of W and Z, which are different, represents -CR4R5- or -(CRxRy)n-, in which, R4 is hydrogen, C1-3 alkyl, C1-3 alkylthio, C1-3 alkoxy or C1-6 alkyl phenyl; R5 is C1-3 alkyl, C1-3 alkylthio, C1-3 alkoxy, phenyl, substituted phenyl, C3-6 cycloalkyl, phenylthio, C1-6 alkyl phenyl, halo-substituted benzyl, or heteroaryl; or together R4 and R5 form a 3 to 6 membered carbocyclic ring, or a heterocyclic ring containing one or two ring oxygen, nitrogen or sulphur atoms, or R4 and R5 together form an oxo or methylene group; each of Rx and Ry is hydrogen or C1-3 alkyl; n is zero or 1; R6 is phenyl substituted aminocarbonyl, C1-6 alkoxy carbonyl-C1-6 alkyl, phenyl-C1-6 alkyl, phenyl, C3-6 cycloalkylcarbonyl, C3-6 cycloalkylcarbonyl-C1-6 alkyl, C3-6 cycloalkyl C1-6 alkyl; C1-6 alkylthiocarbonyl; halo-substituted C1-6 alkoxycarbonyl; C1-6 alkoxy C1-6 alkyleneoxycarbonyl; C1-6 alkylthio C1-6 alkyleneoxycarbonyl; C1-6 alkoxythiocarbonyl; C3-6 cycloalkyloxycarbonyl; cyano substituted C1-6 alkoxycarbonyl; di-C1-6 alkylphosphonate; C1-6 alkenyloxycarbonyl; or R6 is hydrogen when R5 is phenyl, C3-6 cycloalkyl, phenylthio, C1-6 alkylphenyl or halo-substituted benzyl; R6 is benzoyl or aminobenzoyl when R4 and R5 form a C3-6 cycloalkyl ring; R7 is hydrogen, C1-6 alkyl or halogen; X is oxygen or sulphur; and A is sulphur, oxygen or -NH-, is useful for the treatment of heart disease
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- The Invention of New Radical Chain Reactions. Part 9. Further Radical Chemistry of Thiohydroxamic Esters; Formation of Carbon-Carbon Bonds
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Carbon radicals derived from the esters of several types of thiohydroxamic acids have been trapped in a number of different ways.Particular attention has been paid to carbon-carbon bond formation by addition to suitably activated ethylenic linkages.Carboxylic acids can be conveniently converted into homo- and bishomo-acids by free radical chemistry based on thiohydroxamic esters.In a coda the tautomerism of the thiohydroxamic acids have been examined by physical methods.It is confirmed that the esters used are derivatives of the thione tautomer.
- Barton, Derek H.R.,Crich, David,Kretzschmar, Gerhard
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- SYNTHESIS OF CYCLOHEXYLALIPHATIC ACIDS AND THEIR PHARMACOLOGICAL PROPERTIES
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A series of substituted cyclohexylacetic acids I has been obtained by hydrogenation of the unsaturated analogues II and III.Esters of these analogues were prepared by the Horner-Wittig reaction of the corresponding cyclohexanones IV and/or 2-cyclohexenones V with triethyl phosphonoacetate.These esters were obtained in two isomeric forms (Z and E), differing in the double bond in the exo-position.The derivatives with a substituent in the 2-position exhibited a partial shift of the double bond to the cyclohexane ring; this shift was especially marked in the 2-phenyl derivative.With the acids I-III, activation of fibrinolysis was assessed by the hanging clot method; the anti-inflammatory effect was assessed by inhibition of two experimental model inflammations.The regression equation relating fibrinolytic capacity to lipophilicity was a quadratic one, the logarithm of optimum lipophilicity being log Popt = 5.55.A qualitative assessment of the anti-inflammatory effect in relation to lipophilicity suggests that log Popt is probably higher than with arylaliphatic acids.These acids seem to have an active site different from that of the acids I-III.
- Kuchar, Miroslav,Brunova, Bohumila,Grimova, Jaroslava,Vanecek, Stanislav,Holubek, Jiri
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p. 2896 - 2908
(2007/10/02)
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- MESOMORPHOGENS. VI. CHOLESTERYL AND THIOCHOLESTERYL ESTERS OF CYCLOALKANECARBOXYLIC ACIDS
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The acylation of cholesterol and thiocholesterol by acid chlorides of ω-cycloalkane carboxylic acid gave the cholesteryl and thiocholesteryl esters of the corresponding acids.The mesogenic capacity of the ω-cycloalkanoates of cholesterol and thiocholesterol is largely a factor of the polarizability of these molecules and not their spatial configuration.A decrease in the geometric anisotropy and concurrent increase in polarizability impart instability to the meso phase of most ω-cycloalkanoates.
- Bogatskii, A. V.,Kondrat'eva, R. V.,Galatina, A. I.,Novikova, N. S.
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p. 1286 - 1290
(2007/10/02)
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- THE INVENTION OF NEW RADICAL CHAIN REACTIONS. PART X. HIGH YIELD RADICAL ADDITION REACTIONS OF αβ-UNSATURATED NITROOLEFINS. AN EXPEDIENT CONSTRUCTION OF THE 25-HYDROXY-VITAMIN D3 SIDE CHAIN FROM BILE ACIDS.
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Radicals derived from thiohydroxamic esters 3 readily add to nitroolefins 5 (Z=NO2) to give good yields of α-nitrosulphides.These adducts, where the structure permits, are easily oxidised to carboxylic acids 8 by treatment with alkaline hydrogen peroxide.Reductive cleavage to the corresponding aldehydes or ketones 9 is efficiently carried out by the action of TiCl3.Addition of methyl magnesium iodide to methyl ketone derived from 3α-acetoxy 11-oxo cholanic acid gives steroid 10 possessing the 25-hydroxycholesterol side chain of the vitamin D3 metabolites.Radical additions to 1-phenylthio-2-nitropropene 11 have been briefly studied.
- Barton, Derek H.R.,Togo, Hideo,Zard, Samir Z.
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p. 5507 - 5516
(2007/10/02)
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- New Oxidatively Removable Carboxy Protecting Groups
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2,6-Dimethoxybenzyl esters are readily oxidized by 2,3-dichloro-5,6-dicyano benzoquinone (DDQ) to generate the corresponding carboxylic acids.Phenyl esters substituted with hydroxy, methoxy and dimethylamino groups are also efficiently oxidized by ceric ammonium nitrate (CAN) under pH control conditions.
- Kim, C. U.,Misco, P. F.
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p. 2027 - 2030
(2007/10/02)
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- A useful method for preparation of carboxylic acids from terminal alkynes
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Substituted acetic acids can be prepared in good yield (50-80percent) from terminal acetylenes of the same chain length.The alkyne is first converted to the thiophenyl ether, which is treated without purification with mercuric sulfate in acetic acid and 2N sulfuric acid affording the carboxylic acid.The method is particularly useful in the synthesis of long chain ω-hydroxyalkanoic acids.
- Abrams, Suzanne R.
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p. 2423 - 2424
(2007/10/02)
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- New Methods and Reagents in Organic Synthesis. 26. Reductive Desulfonylation of α-Sulfonylacetates
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α-Acyl-benzylsulfonyldiazomethanes (2a-d) have been converted to α-benzylsulfonyl-α-substituted-acetic acids (7a-d) by means of the Wolff rearrangement.Reductive removal of the benzylsulfonyl group of 7b-d can be achieved by the use of sodium-ethanol in tetrahydrofuran. α-Benzylsulfonyl-α-substituted-propionic acids (9a-d), prepared from benzyl α-benzylsulfonyl-α-substituted-acetates (3a-d), were also debenzylsulfonylated under similar reductive conditions.The overall process, in combination with the Arndt-Eistert synthesis of α-sulfonylacetates from acyl chlorides and benzylsulfonyldiazomethane (1), provides a new, safe method for the homologation of carboxylic acids.Keywords-reductive desulfonylation; Wolff rearrangement; sodium amalgam reduction; catalytic debenzylation; sodium-ethanol reduction; methylation; α-substituted propionic acid; α-sulfonylacetate
- Kuo, Ying-Che,Aoyama, Toyohiko,Shioiri, Takayuki
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p. 2787 - 2792
(2007/10/02)
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