- High turnover in electro-oxidation of alcohols and ethers with a glassy carbon-supported phenanthroimidazole mediator
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Glassy carbon electrodes covalently modified with a phenanthroimidazole mediator promote electrochemical alcohol and ether oxidation: three orders of magnitude increase in TON, to ~15 000 in each case, was observed compared with homogeneous mediated reactions. We propose the deactivation pathways in homogeneous solution are prevented by the immobilization: modified electrode reversibility is increased for a one-electron oxidation reaction. The modified electrodes were used to catalytically oxidize p-anisyl alcohol and 1-((benzyloxy)methyl)-4-methoxybenzene, selectively, to the corresponding benzaldehyde and benzyl ester, respectively.
- Johnson, Bruce M.,Francke, Robert,Daniel Little,Berben, Louise A.
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Read Online
- N-Aroylbenzotriazoles as Efficient Reagents for o-Aroylation in Absence of Organic Solvent
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N-Aroylbenzotriazoles have been shown to be efficient reagents for esterification in the absence of organic solvent. Grinding of N-aroylbenzoytiazoles with twofold excess of alcohols for a couple of hours at room temperature gave corresponding esters in high percentage of yields.
- Hahnvajanawong, Viwat,Phungpis, Baramee
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p. 2671 - 2674
(2021/10/25)
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- Pd-Catalysed Decarbonylation Free Approach to Carbonylative Esterification of 5-HMF to Its Aryl Esters Synthesis Using Aryl Halides and Oxalic Acid as C1 Source
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A decarbonylation free, polystyrene-supported, Pd (Pd@PS)-catalysed carbonylative esterification of the hydroxy group of 5-hydroxymethyl furfural (5-HMF) to its corresponding aryl esters has been developed. The use of Pd@PS, oxalic acid as CO source, and aryl halides was first explored for the aryl ester of 5-HMF synthesis. Here, we investigated the vital role of a polystyrene support to avoid the commonly known decarbonylation of 5-HMF. The reaction exhibits vast substrate scope with comparably good yield and catalyst recyclability.
- Singh Chauhan, Arvind,Kumar, Ajay,Kumar Sharma, Ajay,Das, Pralay
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supporting information
p. 12971 - 12975
(2021/08/06)
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- Ynoate-Initiated Selective C-N Esterification of Tertiary Amines under Transition-Metal and Oxidant-Free Conditions
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An efficient and selective method for metal-and oxidant-free deaminated esterification of tertiary amines is presented. In this protocol, ynoates play a key role to activate the Csp 3-N bond through a process of in situ generation of zwitterionic salts. The transformations show that Csp 3-N bond in the zwitterionic species has a lower dissociation energy than Csp 2-N bond, leading to break preferentially and be trapped by carboxylic acids to generate the corresponding products in moderate to good yield.
- Sun, Feixiang,Feng, Huangdi,Huang, Liliang,Huang, Junhai
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supporting information
p. 713 - 717
(2021/01/14)
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- Iodine-catalyzed synthesis of β-uramino crotonic esters as well as oxidative esterification of carboxylic acids in choline chloride/urea: a desirable alternative to organic solvents
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Abstract: Iodine-mediated selective synthesis of β-uramino crotonic esters was achieved via the reaction of β-dicarbonyls and urea at room temperature. Choline chloride/urea mixture, as an eco-friendly, cheap, non-toxic, and recyclable deep eutectic solvent (DES), was employed as sustainable media as well as reagent at the same time in these transformations. Some derivatives of β-uramino crotonic esters were synthesized with good to high yields without a tedious work-up. The process could be done to synthesize the above-mentioned compounds in gram scale. Moreover, oxidative cross-esterification of carboxylic acids with alkyl benzenes was carried out in the above-mentioned DES by the employment of tetrabutylammonium iodide (TBAI) as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant at 80?°C. DES/TBAI system was reused up to five consecutive times. Graphic abstract: Iodine-catalyzed C–N and C–O bond formation in choline chloride/urea as a green solvent under the mild reaction conditions. Providing the clean procedure toward synthesis of β-uramino crotonic esters and benzylic esters.[Figure not available: see fulltext.].
- Moayyed, Mohammadesmaeil,Saberi, Dariush
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p. 445 - 455
(2020/09/07)
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- Quinolin-8-yl Formate: A New Option for Small-Scale Carbonylation Reactions in Microwave Reactors
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A convenient procedure for conducting small-scale carbonylations of aryl or benzyl halides in a microwave reactor by using quinolin-8-yl formate is described. The resulting 8-acyloxyquinolines were shown to be more reactive than phenyl esters in acyl-tran
- Maddocks, Christopher J.,Aathimanikandan, Sivakumar V.,Richardson, Jeffery,Ruble, J. Craig
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supporting information
p. 1608 - 1612
(2020/09/09)
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- A metal-free iodine-mediated conversion of hydroxamates to esters
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A metal-, oxidant-, and additive-free conversion of hydroxamates to esters have been achieved using molecular iodine as the reagent using a novel but not-so-explored heron-type rearrangement. The reaction proceeds with almost equal facility with substrates having either electron-donating or electron-withdrawing substituent. Similarly, α,?-unsaturated, and sterically hindered ortho-substituted hydroxamates also undergo the desired transformation smoothly.
- Ghosh, Subhankar,Banerjee, Jeet,Ghosh, Rajat,Chattopadhyay, Shital K.
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p. 1353 - 1360
(2020/03/30)
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- Mechanochemical Palladium-Catalyzed Carbonylative Reactions Using Mo(CO)6
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Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide.
- van Bonn, Pit,Bolm, Carsten,Hernández, José G.
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p. 2576 - 2580
(2020/02/20)
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- Bu 4 NI-Catalyzed C-C Bond Cleavage and Oxidative Esteri??cation of Allyl Alcohols with Toluene Derivatives
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A novel oxidative esterification of 1-arylprop-2-en-1-ols with toluene derivatives catalyzed by tetrabutylammonium iodide (TBAI) is reported. The optimization of the reaction conditions illustrates that each of experiment parameters including the catalyst, solvent, and oxidant is significant for present oxidative functionalization. This metal-free protocol has a broad substrate scope including the halogen groups for further functionalization and enriches the reactivity profile of allyl alcohol and toluene derivatives. In addition, this protocol represents a new transformation of allyl alcohol involving C-C bond cleavage and C-O bond forming.
- Chen, Yaoyao,Cui, Yongmei,Jia, Xueshun,Li, Chengliang,Li, Jian,Sun, Mingming
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p. 3667 - 3674
(2019/09/30)
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- A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage
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An efficient, simple, and metal-free synthetic approach for the N- and O-benzoylation of various amines/benzyl alcohols with pyridinium salts of phenacyl bromides is demonstrated to generate the corresponding amides and esters. This protocol facilitates the oxidative cleavage of a C–C bond followed by formation of a new C–N/C–O bond in the presence of K2CO3. Various pyridinium salts of phenacyl bromides can be readily transformed into a variety of amides and esters which is an alternative method for the conventional amidation and esterification in organic synthesis. High functional group tolerance, broad substrate scope and operational simplicity are the prominent advantages of the current protocol.
- Manasa, Kesari Lakshmi,Tangella, Yellaiah,Krishna, Namballa Hari,Alvala, Mallika
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p. 1864 - 1871
(2019/08/12)
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- Palladium-Catalyzed Carbonylative Synthesis of Benzyl Benzoates Employing Benzyl Formates as Both CO Surrogates and Benzyl Alcohol Sources
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An efficient and convenient palladium-catalyzed carbonylation reaction for the synthesis of benzyl benzoates from aryl bromides has been developed. Benzyl formates have been explored as a new type of efficient and useful CO sources and also reaction partners. A wide range of benzyl benzoates was obtained in good to excellent yields.
- Lai, Ming,Qi, Xinxin,Wu, Xiao-Feng
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supporting information
p. 3776 - 3778
(2019/06/24)
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- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
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The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
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p. 2797 - 2800
(2019/03/27)
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- Microwave-assisted direct thioesterification of carboxylic acids
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A one-pot synthesis of thioesters directly from carboxylic acids, N,N′-diphenylthiourea, triethylamine, and primary alkyl halides is described. Microwave-assisted heating and a catalytic amount of 4- (dimethylamino)pyridine (DMAP) further improved the yields. Both aromatic and aliphatic carboxylic acids were converted to the corresponding thioesters, and many functional groups were compatible with this reaction. Several possible reaction intermediates were investigated, and the quaternary ammonium salts, derived from alkyl halides and tertiary amines, were the intermediates to yield thioesters. A new reaction mechanism for this thioesterification is proposed.
- Chou, Yen-Lin,Jhong, Yi,Swain, Sharada Prasanna,Hou, Duen-Ren
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p. 10201 - 10208
(2018/05/31)
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- Cobalt-Catalyzed Esterification of Amides
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The first cobalt-catalyzed amide activation of N-Boc-amides, and their conversion into esters, is reported here. This new methodology presents a very practical process that does not require an inert atmosphere, uses an inexpensive cobalt catalyst, and proceeds under mild reaction conditions. This catalytic system has a broad substrate scope and has been shown to be highly efficient, with catalyst loadings as low as 1 mol %.
- Bourne-Branchu, Yann,Gosmini, Corinne,Danoun, Grégory
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supporting information
p. 10043 - 10047
(2017/08/01)
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- Rhodium-catalyzed synthesis of esters from aryl iodides and alcohols: use of alcohols with/without the assistance of aldehydes as carbon monoxide and nucleophile sources
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A CO-gas-free rhodium-catalyzed alkoxycarbonylation of aryl iodide with alcohols has been developed. Alcohols, with/without the aid of an aldehyde, were used as a carbon monoxide and nucleophile source. The former synthesis afforded better yields of the alkoxycarbonylated products. Moreover, phenols also afforded phenoxycarbonylation products with high yields.
- Kim, Ju Hyun,Park, Hawon,Chung, Young Keun
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p. 190 - 194
(2017/01/12)
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- Room Temperature Carbonylation of (Hetero) Aryl Pentafluorobenzenesulfonates and Triflates using Palladium-Cobalt Bimetallic Catalyst: Dual Role of Cobalt Carbonyl
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An efficient method for the carbonylation of (hetero) aryl pentafluorobenzenesulfonates and triflates under exceptionally mild conditions using palladium/dicobalt octacarbonyl [Pd/Co2(CO)8] has been developed. Besides acting as carbon monoxide (CO) source, Co2(CO)8enhances the reaction rate by accelerating the CO insertion through an in situ generated bimetallic palladium cobalt tetracarbonyl [Pd-Co(CO)4] complex. Under the optimized reaction condition, carbonylation of a wide range of activated and deactivated, as well as sterically hindered and heteroaromatic, substrates proceeded efficiently at room temperature. The high chemoselectivity and improved synthesis of biologically relevant Isoguvacine and Lazabemide intermediates highlights its scope as a valuable synthetic method. The generality of this protocol was further extended to other electrophiles (bromides, chlorides and tosylates). (Figure presented.).
- Joseph, Jayan T.,Sajith, Ayyiliath M.,Ningegowda, Revanna C.,Shashikanth, Sheena
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supporting information
p. 419 - 425
(2017/02/10)
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- Synthesis method of carboxylic ester compound
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The invention provides a synthesis method of an ester compound represented by the formula (1), the formula (2) or the formula (3), wherein the method comprises the steps: dissolving an aldehyde compound, sodium azide, tetrabutylammonium iodide and a halogenated compound in a solvent, or directly dissolving an aldehyde compound, sodium azide and tetrabutylammonium iodide in a halogenated compound, carrying out a reaction for 1-12 h at the temperature of 90-100 DEG C, and after the reaction is finished, postprocessing the reaction liquid to obtain the compound represented by the formula (1). The synthesis method has the advantages of mild reaction conditions, no participation of strong acids, strong alkalis or metals, simpliness, high efficiency, high yield, wide application range of substrates, amplified production potential, and relatively large potential economic value.
- -
-
Paragraph 0049; 0050; 0051; 0123; 0124; 0125
(2017/08/28)
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- Esterification of the Primary Benzylic C-H Bonds with Carboxylic Acids Catalyzed by Ionic Iron(III) Complexes Containing an Imidazolinium Cation
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The first iron-catalyzed esterification of the primary benzylic C-H bonds with carboxylic acids using di-tert-butyl peroxide as an oxidant is achieved by novel ionic iron(III) complexes containing an imidazolinium cation. The use of well-defined, air-stable, and available iron(III) complex in a 5 mol % loading and readily available starting materials with a broad generality and outstanding sterically hindered tolerance renders this methodology a useful alternative to other protocols that are typically employed for the synthesis of benzyl esters.
- Lu, Bing,Zhu, Fan,Sun, Hong-Mei,Shen, Qi
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supporting information
p. 1132 - 1135
(2017/03/14)
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- Reusable ionic liquid-catalyzed oxidative esterification of carboxylic acids with benzylic hydrocarbons via benzylic Csp3-H bond activation under metal-free conditions
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A metal-free protocol for the direct oxidative esterification of the Csp3-H bond in benzylic hydrocarbons with carboxylic acids using heterocyclic ionic liquid as catalyst has been reported. The catalyst 1-butylpyridinium iodide could be easily recycled and reused for at least four cycles without obvious loss of catalytic activity.
- Mou, Fen,Sun, Yadong,Jin, Weiwei,Zhang, Yonghong,Wang, Bin,Liu, Zhiqing,Guo, Lei,Huang, Jianbin,Liu, Chenjiang
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p. 23041 - 23045
(2017/07/10)
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- The invention relates to a raw material synthetic ester of carboxylic acid and alcohol method (by machine translation)
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The invention discloses a carboxylic acid and alcohol as the raw material ester method. The method uses three benzene oxygen phosphine/oxalyl system as carboxylic acid activator, to organic base as catalyst, carboxylic acid and alcohol in carboxylic acid activator and reacting under action of catalyst to generate ester. The present invention is carried out under inert atmosphere, the reaction temperature is 10 - 40 °C, the reaction time is 0.5 - 5 hours; the reaction triphenyl oxygen phosphorus, oxalyl, carboxylic acid and alcohol of the amount-of-substance ratio is (0.5 - 2): (0.6 - 2.3): 1: (0.6 - 2.3). The invention the reaction temperature is low, the reaction time is short, carboxylic acid activator are cheap and easily obtained, and can be recovered for reuse, of low cost; the reaction by-product only CO and CO2 , Has higher utilization rate of atom, is suitable for industrial application. (by machine translation)
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Paragraph 0029-0030
(2017/03/18)
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- METHOD OF CONVERTING ALCOHOL TO HALIDE
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The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
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Page/Page column 50; 66; 67
(2017/01/02)
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- Pd/C-Catalyzed Carbonylative Esterification of Aryl Halides with Alcohols by Using Oxiranes as CO Sources
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A carbonylative esterification reaction between aryl bromides and alcohols, promoted by Pd/C and NaF in the presence of oxiranes, has been developed. In this process, oxiranes serve as sources of carbon monoxide by their conversion to aldehydes through a palladium-promoted Meinwald rearrangement pathway. Intramolecular versions of this process serve as methods for the synthesis of lactones and phthalimides. CO gas free! A carbonylative esterification reaction between aryl bromides and alcohols, promoted by Pd/C and NaF in the presence of oxiranes, has been developed. In this process, oxiranes serve as sources of carbon monoxide by their conversion to aldehydes through a palladium-promoted Meinwald rearrangement pathway (see scheme).
- Min, Byul-Hana,Kim, Dong-Su,Park, Hyo-Soon,Jun, Chul-Ho
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supporting information
p. 6234 - 6238
(2016/05/02)
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- Cu(ii)-catalyzed esterification reaction via aerobic oxidative cleavage of C(CO)-C(alkyl) bonds
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A novel Cu(ii)-catalyzed aerobic oxidative esterification of simple ketones for the synthesis of esters has been developed with wide functional group tolerance. This process is assumed to go through a tandem sequence consisting of α-oxygenation/esterification/nucleophilic addition/C-C bond cleavage and carbon dioxide is released as the only byproduct.
- Ma, Ran,He, Liang-Nian,Liu, An-Hua,Song, Qing-Wen
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supporting information
p. 2145 - 2148
(2016/02/09)
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- NOVEL SINGLE STEP ESTERIFICATION PROCESS OF ALDEHYDES USING A HETEROGENEOUS CATALYST
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The present invention relates to a novel simple, efficient and single-step process for esterification of aldehydes using a heterogeneous catalyst with high yields. More particularly, the present invention relates to a novel simple, efficient and single-step process for esterification of aldehydes using Titanium superoxide with greater than 80% yields.
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Page/Page column 8; 9; 11
(2016/06/20)
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- Synthetic method of an ester compound
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The invention discloses a synthetic method of an ester compound and belongs to the technical field of organic synthesis. The synthetic method includes the steps of: dissolving an aldehyde compound (1) and a halogenated hydrocarbon compound (2) in a solvent, adding an oxidant and a catalyst, and performing a reaction at 60-100 DEG C to obtain the target product ester compound (3). A reaction equation of the synthetic method is represented as follows. The method, compared with the prior art, has the following advantages: 1) the raw materials are easy to obtain and are low in cost; 2) the reaction conditions are mild, operations are simple, and reaction time is short; and 3) a substrate has wide available range and can be used for synthesis of various ester compounds.
- -
-
Paragraph 0090; 0091; 0092
(2017/02/02)
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- Metal-free, room-temperature, radical alkoxycarbonylation of aryldiazonium salts through visible-light photoredox catalysis
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The first radical alkoxycarboxylation of aryldiazonium salts using CO gas through visible-light-induced photoredox catalysis (16 W blue LEDs) has been developed. This reaction is entirely metal-free, is carried out at room temperature with a low loading of an organic dye as a photocatalyst (0.5 mol%), and provides a wide range of arylcarboxylic acid esters in high yields. Importantly, this photocatalytic system can be successfully extended to other carboxylation reactions.
- Guo, Wei,Lu, Liang-Qiu,Wang, Yue,Wang, Ya-Ni,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 2265 - 2269
(2015/02/19)
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- Nickel-catalyzed dehydrogenative cross-coupling: Direct transformation of aldehydes into esters and amides
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By exploring a new mode of nickel-catalyzed cross-coupling, a method to directly transform both aromatic and aliphatic aldehydes into either esters or amides has been developed. The success of this oxidative coupling depends on the appropriate choice of catalyst and organic oxidant, including the use of either α,α,α-trifluoroacetophenone or excess aldehyde. Mechanistic data that supports a catalytic cycle involving oxidative addition into the aldehyde C-H bond is also presented.
- Whittaker, Aaron M.,Dong, Vy M.
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supporting information
p. 1312 - 1315
(2015/01/30)
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- N-Heterocyclic Carbene-Mediated Oxidative Electrosynthesis of Esters in a Microflow Cell
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An efficient N-heterocyclic carbene (NHC)-mediated oxidative esterification of aldehydes has been achieved in an undivided microfluidic electrolysis cell at ambient temperature. Productivities of up to 4.3 g h-1 in a single pass are demonstrated, with excellent yields and conversions for 19 examples presented. Notably, the oxidative acylation reactions were shown to proceed with a 1:1 stoichiometry of aldehyde and alcohol (for primary alcohols), with remarkably short residence times in the electrolysis cell (13 s), and without added electrolyte. (Chemical Equation Presented).
- Green, Robert A.,Pletcher, Derek,Leach, Stuart G.,Brown, Richard C. D.
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supporting information
p. 3290 - 3293
(2015/07/15)
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- Titanium superoxide-a stable recyclable heterogeneous catalyst for oxidative esterification of aldehydes with alkylarenes or alcohols using TBHP as an oxidant
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Titanium superoxide efficiently catalysed the oxidative esterification of aldehydes with alkylarenes or alcohols, under truly heterogeneous conditions, to afford the corresponding benzyl and alkyl esters in excellent yields. Mechanistic studies have established that this "one pot" direct oxidative esterification process proceeds through a radical pathway, proven by a FTIR spectral study of a titanium superoxide-aldehyde complex as well as spin trapping experiments with TEMPO. The intramolecular version of this protocol has been successfully demonstrated in the concise synthesis of 3-butylphthalide, an anti-convulsant drug.
- Dey, Soumen,Gadakh, Sunita K.,Sudalai
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p. 10631 - 10640
(2015/11/17)
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- Ester manufacturing method (by machine translation)
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PROBLEM TO BE SOLVED: To produce an ester compound by transesterification using an inexpensive and low toxic inorganic compound. SOLUTION: Transesterification of an ester compound and an alcohol compound is carried out under the presence of lanthanum nitrate (for example, lanthanum nitrate hexahydrate) and a phosphine compound (for example, tri-n-octylphosphine), thereby obtaining the ester product. For example, transesterification of dimethyl carbonate and benzyl alcohol is carried out under the presence of 1 mol% of lanthanum nitrate hexahydrate, and 2 mol% of tri-n-octylphosphine, thereby obtaining benzyl methylcarbonate at a yield of >99%. COPYRIGHT: (C)2012,JPO&INPIT
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Paragraph 0054; 0055; 0056
(2017/02/17)
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- Versatile and sustainable alcoholysis of amides by a reusable CeO 2 catalyst
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CeO2 catalyzed the esterification between an equivalent molar ratio of primary amides and alcohols under neutral conditions, which provides the first versatile reusable catalytic system for direct alcoholysis of amides to esters with wider scope and 67 times higher turnover number (TON) than previous catalytic systems.
- Siddiki, S. M. A. Hakim,Touchy, Abeda Sultana,Tamura, Masazumi,Shimizu, Ken-Ichi
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p. 35803 - 35807
(2014/11/07)
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- Direct, rapid and convenient synthesis of esters and thioesters using PPh3/N-chlorobenzotriazole system
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We have developed an efficient method for esterification and thioesterification of various carboxylic acids with different alcohols and thiols using PPh3/N-chlorobenzotriazole mixed reagent in CH2Cl2 at room temperature.
- Rouhi-Saadabad, Hamed,Akhlaghinia, Batool
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p. 253 - 263
(2014/02/14)
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- Fe3O4 supported Pd(0) nanoparticles catalyzed alkoxycarbonylation of aryl halides
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This paper describes the simple and efficient method for the alkoxycarbonylation of aryl iodides using magnetically recoverable Pd/Fe 3O4 as the catalyst under atmospheric pressure of carbon monoxide. Various aryl iodides on alkoxycarbonylation with alcohols gave the corresponding products in good to excellent yields. The catalyst is completely recoverable with the simple application of an external magnetic field, and the efficiency of the catalyst remains unaltered even after five cycles.
- Siva Prasad, Aviraboina,Satyanarayana, Bollikonda
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p. 205 - 209
(2013/04/23)
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- Transition metal free oxidative esterification of alcohols with toluene
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Using Bu4NI as the catalyst and tert-butyl hydroperoxide as the oxidant, direct esterification of alcohols with toluene derivatives was achieved. Mechanistic investigations indicate that the alcohols are sequentially oxidized to aldehydes, carboxylic acids, and then to benzyl esters. Bu 4N+ functions as a phasetransfer reagent and iodide catalyzes the reaction.
- Liu, Lianghui,Yun, Lin,Wang, Zikuan,Fu, Xuefeng,Yan, Chun-Hua
-
supporting information
p. 5383 - 5386
(2013/09/12)
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- Aniline mediated oxidative C-C bond cleavage of α-alkoxy aldehydes in air and a model reaction for the synthesis of α-(d)-amino acid derivatives
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A metal-free and 4-methyl aniline mediated method for the oxidative C-C bond cleavage has been developed. The reaction proceeds in air using molecular oxygen as the oxidant, affording one-carbon shortened esters in moderate to good yields within a short time. Moreover, it provides a model reaction for the highly enantioselective synthesis of (d)-serine esters by combining with a l-proline catalyzed Mannich reaction.
- Hu, Bin,Li, Yunfeng,Li, Zhongjun,Meng, Xiangbao
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p. 4138 - 4141
(2013/07/05)
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- Cooperative N-Heterocyclic Carbene (NHC) and Ruthenium Redox Catalysis: Oxidative Esterification of Aldehydes with Air as the Terminal Oxidant
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The paper describes a cooperative NHC (N-heterocyclic carbene) and ruthenium-based redox catalysis for the mild aerobic oxidative esterification of various aromatic and heteroaromatic aldehydes. The ruthenium(II) complex Ru(bpz)3(PF6)2 (bpz=2,2′-bipyrazine) as catalyst is shown to be compatible with free NHCs. The NHC is used in these cascade reactions for the umpolung of the aldehyde to form the corresponding Breslow intermediate which in turn gets oxidized to an acylazolium ion by the ruthenium redox catalyst. Air is used as a terminal oxidant for oxidation (regeneration) of the ruthenium catalyst. In addition, we will show that in the absence of the ruthenium redox catalyst and alcohol, NHC-catalyzed aerobic oxidation of aldehydes delivers the corresponding acids in good to excellent yields. Mechanistic studies and DFT calculations supporting our suggested mechanisms are provided. Copyright
- Zhao, Junfeng,Mueck-Lichtenfeld, Christian,Studer, Armido
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supporting information
p. 1098 - 1106
(2013/05/21)
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- Palladium-catalyzed benzylation of carboxylic acids with toluene via benzylic C-H activation
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Direct benzylation of carboxylic acids with toluene has been developed via palladium-catalyzed C-H acyloxylation under 1 atm of oxygen. This reaction demonstrates good functional group tolerance and high yields, providing a facile, atom-economic, and efficient method for the synthesis of benzyl esters.
- Liu, Hongqiang,Shi, Guangfa,Pan, Shulei,Jiang, Yuyu,Zhang, Yanghui
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supporting information
p. 4098 - 4101
(2013/09/12)
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- Preparation of esters and amides from carboxylic acids and N-formylation of amines promoted by 1,3,5-triazo-2,4,6-triphosphorine-2,2,4,4,6,6-hexachloride (TAPC)
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A new method is described for the preparation of esters and amides promoted by TAPC from carboxylic acids using a solvent-free grinding technique. The solvent-free N-formylation of amines is also reported.
- Bahrami, Kiumars,Khodaei, Mohammad M.,Targhan, Homa,Sheikh Arabi, Mehdi
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supporting information
p. 5064 - 5068
(2013/09/02)
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- In situ generated "lanthanum(iii) nitrate alkoxide" as a highly active and nearly neutral transesterification catalyst
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In situ generated lanthanum(iii) nitrate alkoxide is a highly active and nearly neutral transesterification catalyst, which can promote non-epimerized transesterification of α-substituted chiral carboxylic esters under reflux conditions.
- Hatano, Manabu,Kamiya, Sho,Ishihara, Kazuaki
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supporting information
p. 9465 - 9467
(2012/10/29)
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- Copper catalyzed oxidative esterification of aldehydes with alkylbenzenes via cross dehydrogenative coupling
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Copper(II) as the catalyst in a cross dehydrogenative coupling (CDC) reaction has been demonstrated for the synthesis of benzylic esters using aldehydes and alkylbenzenes as coupling partners.
- Rout, Saroj Kumar,Guin, Srimanta,Ghara, Krishna Kanta,Banerjee, Arghya,Patel, Bhisma K.
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supporting information; experimental part
p. 3982 - 3985
(2012/09/22)
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- NHCs-mediated benzoates formation directly from aromatic aldehydes and alkyl halides
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A NHCs-mediated benzoates formation was developed by treatment of aromatic aldehydes with alkyl halides in the presence of oxygen. Corresponding benzoate derivatives were obtained in high yields up to 99%. The reaction mechanism was also discussed and a NHCs-mediated O-alkylation and subsequent oxidation process was proposed.
- Li, Yi,Du, Wenting,Deng, Wei-Ping
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p. 3611 - 3615
(2012/06/15)
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- A metal-free oxidative esterification of the benzyl C-H bond
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An efficient metal-free oxidative esterification of benzyl C-H bonds was developed. Using tetrabutylammonium iodide as catalyst and tert-butyl hydroperoxide as co-oxidant, benzylic substrates could react smoothly with various carboxylic acids to give the esters with good to excellent yields. The method was also suitable for the O-protection of N-Boc amino acids. The reaction mechanism was primarily investigated and a radical process was proposed. Copyright
- Feng, Jie,Liang, Shuai,Chen, Shan-Yong,Zhang, Ji,Fu, Song-Sen,Yu, Xiao-Qi
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scheme or table
p. 1287 - 1292
(2012/06/15)
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- Novel triarylimidazole redox catalysts: Synthesis, electrochemical properties, and applicability to electrooxidative C-H activation
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A new class of metal-free, easy to synthesize redox catalysts based on a triarylimidazole framework is described. With those synthesized thus far, one can access a potential range of ca. 410 mV. They proved to be useful mediators for the activation of benzylic C-H bonds under mild conditions.
- Zeng, Cheng-Chu,Zhang, Ni-Tao,Lam, Chiu Marco,Little, R. Daniel
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supporting information; experimental part
p. 1314 - 1317
(2012/04/23)
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- Equilibrium shift in the rhodium-catalyzed acyl transfer reactions
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Rhodium/phosphine complexes catalyze equilibrium acyl transfer reactions between acid fluorides, aryl esters, acylphosphine sulfides, and thioesters. The use of appropriate co-substrates to accept heteroatom groups shifted the equilibrium to desired products. Acylphosphine sulfides and aryl esters were converted to acid fluorides using benzoylpentafluorobenzene as the fluoride donor, and the fluorination reaction of thioesters employed (4-tolylthio) pentafluorobenzene. Acid fluorides were converted into acylphosphine sulfides and thioesters using diphosphine disulfides and disulfides/triphenylphosphine, respectively. Aryl esters were obtained from acid fluorides and phenols in the presence of triphenylsilane. Aryl esters, acylphosphine sulfides, and thioesters were also interconverted in the presence of rhodium complexes. These rhodium-catalyzed acyl transfer reactions proceeded under neutral conditions without using acid or base. The involvement of acyl rhodium intermediates in these reactions was suggested by the carbothiolation reaction of thioesters and alkynes.
- Arisawa, Mieko,Igarashi, Yui,Kobayashi, Haruki,Yamada, Toru,Bando, Kentaro,Ichikawa, Takuya,Yamaguchi, Masahiko
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p. 7846 - 7859
(2011/10/12)
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- Base-induced mechanistic variation in palladium-catalyzed carbonylation of aryl iodides
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A mechanism, which is distinct from the traditional one when sodium alkoxide was used instead of tertiary amines, was proposed for the alkoxycarbonylation of aryl iodides. The catalytic cycle was composed of oxidative addition, subsequent ArPdOR formation, CO insertion to Pd-OR, and final reductive elimination of ArPdCOOR. The kinetic simultaneity of the formation of deiodinated side product from the aryl iodide and aldehyde from corresponding alcohol provided strong evidence for the existence of ArPdOR species. The observation of thioether, as the other competitive product in palladium catalyzed thiocarbonylation of aryl iodides and sodium alkylthiolate, also indicate the possibility of metathesis between ArPdl and sodium alkylthiolate. Preliminary kinetic studies revealed that neither oxidative addition nor reductive elimination was rate limiting. DFT calculation displayed preference for CO insertion into Pd-OR bond. The advantage of this novel mechanism had been demonstrated in the facile alkoxycarbonylation and thiocarbonylation. The ethoxycarbonylation of aryl iodides under room temperature and balloon pressure of CO in the presence of EtONa were examined, and good to high yields were obtained; the t-butoxycarbonylation reactions in the presence of t-BuONa were achieved, and the alkylthiocarbonylation (including the t-butylthiocarbonylation) of aryl iodides in the presence of sodium alkylthiolate were also investigated.
- Hu, Yanhe,Liu, Jing,Lu, Zhixin,Luo, Xiancai,Zhang, Heng,Lan, Yu,Lei, Aiwen
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supporting information; experimental part
p. 3153 - 3158
(2010/05/15)
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- Microwave-assisted methylation of phenols with tetramethylammonium chloride in the presence of K2CO3 or Cs2CO3
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We have evaluated the potential of using tetramethylammonium chloride (Me4NCl) as an alternative methylating agent for phenols under microwave-assisted conditions. Its chemical behavior was tested in a reaction with 2-naphthol in the presence of various bases and solvents. The method was then applied in 1,2-dimethoxyethane or toluene under heterogeneous conditions for the O-methylation of a series of phenolic compounds. We found that many simple phenols can be methylated in the presence of K2CO3, whereas some other less-reactive phenols require the presence of the more reactive Cs2CO3.
- Mara?, Nenad,Polanc, Slovenko,Ko?evar, Marijan
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experimental part
p. 11618 - 11624
(2009/04/05)
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- Effect of natural and synthetic benzyl benzoates on calmodulin
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The present investigation describes the effect of the spasmolytic benzylbenzoates 1-9 from Brickellia veronicifolia on CaM using a functional in vitro enzymatic assay. Bovine brain PDE1 was used as a monitoring enzyme. The most active natural inhibitors of the system CaM-PDE1 were benzyl benzoates 3-5, which inhibited the activity of PDE1 in a concentration-dependent manner. In addition, three series of analogs of compound 4, compounds 10a-32a, were prepared and assayed. The benzyl benzoates from the first series, namely 10a-24a, possess no substituents on ring B but different number and position of hydroxyl or methoxy groups in ring A. The second group (25-32a), on the other hand, possesses an A ring identical to that on compound 4, but different substituents in Ring B. The most active compounds were 14a, 15a and 30a. These compounds were two to six times more potent than chlorpromazine, a well known CaM inhibitor. Benzyl benzoates 14a and 15a have methoxyl groups at C-2/C-4 and C-3/C-4 in ring A, respectively; while 30a, in addition to the methoxyl groups at C-2/C-6 of ring A, hold a benzoyloxy moiety at C-3′ of ring B. Kinetic studies revealed that compounds 3, 4, 14a, 15a and 30a behave as competitive CaM antagonists.
- Rivero-Cruz, Blanca,Rivero-Cruz, Isabel,Rodriguez-Sotres, Rogelio,Mata, Rachel
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p. 1147 - 1155
(2007/10/03)
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- A fast and simple method for the acylation of alcohols with acid chlorides promoted by metallic samarium
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Acylation of primary, secondary, allyl and benzyl alcohols with acid chlorides promoted by samarium metal under neutral condition gave carboxylic acid esters in good to excellent yields. Acylation of a tertiary alcohol did not occur under the same reaction conditions.
- Jia, Xue-Shun,Wang, Hai-Long,Huang, Qing,Kong, Ling-Long,Zhang, Wei-He
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p. 135 - 138
(2007/10/03)
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- Surfactant-mediated solvent-free dealkylative cleavage of ethers and esters and trans-alkylation under neutral conditions
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A simple, surfactant-mediated, one-pot, solvent-free dealkylative cleavage of aryl ethers and esters followed by subsequent optional trans-alkylation under essentially neutral conditions has been developed.
- Bhattacharya, Apurba,Patel, Nitin C.,Vasques, Tomas,Tichkule, Ritesh,Parmar, Gaurang,Wu, Jiejun
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p. 565 - 567
(2007/10/03)
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