- GAS-PHASE PYROLYTIC REACTIONS. PART 3. HAMMETT ρ CONSTANTS OF GAS-PHASE ELIMINATIONS OF ALKYLARYLCARBOXYLATE AND ETHANOATE ESTERS AND THEIR CORRELATION WITH SUBSTRATE MOLECULAR FRAMEWORK
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The kinetics of the gas-phase thermal elimination of seven tert-butyl (hetero)arylcarboxylate esters (GCO2But) were measured over a temperature range 50 K; the groups were the phenyl, 3- and 4-pyridyl, 2- and 3-furyl, and 2- and 3-thienyl moieties.The reactions were homogeneous and unimolecular with log A/s-1 scaling 12.45 +/- 0.44, and with an entropy of activation uniformly negative and small.The kinetics obeyed a first-order rate equation, and at 600 K the rate coefficients (103k/s-1) of the esters, in the order given above, were: 54.1, 85.3, 120.5, 76.9, 43.2, 86.3 and 46.1, respectively.Hammett correlation of the present kinetic data with the literature ρ0 - values of the given substituents gave a reaction ρ constant compatible with the ethanoate molecular frame rather than with the carboxylate structure.The physical constants of five new t-butyl heteroarylcarboxylate esters are also described.
- Al-Awadi, Nouria A.,Al-Bashir, Rasha F.,ElDusouqui, Osman M. E.
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- Synthesis of [2,2’]Bifuranyl-5,5’-dicarboxylic Acid Esters via Reductive Homocoupling of 5-Bromofuran-2-carboxylates Using Alcohols as Reductants?
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Herein, we describe an environmentally benign and cost-effective protocol for the synthesis of valuable bifuranyl dicarboxylates, starting with α-bromination of readily accessible furan-2-carboxylates by LiBr and K2S2O8. Furthermore, the bromination intermediate product 5-bromofuran-2-carboxylates were then conducted in a palladium-catalyzed reductive homocoupling reactions in the presence of alcohols to afford bifuranyl dicarboxylates. One of the final products in this protocol, [2,2’]bifuran-5,5’-dicarboxylic acid esters, are essential monomers of poly(ethylene bifuranoate), which can be served as an green and versatile alternative polymer for traditional poly(ethylene terephthalate) that is currently common in technical plastics.
- Jiang, Huanfeng,Luo, Jiajun,Xie, Yi,Yin, Biaolin,Yu, Bin
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- Direct Alkoxycarbonylation of Heteroarenes via Cu-Mediated Trichloromethylation and in Situ Alcoholysis
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We report an efficient approach for direct alkoxycarbonylation of furans as well as other heteroarenes via a one-step copper-mediated reaction of three components (i.e., heteroarene, alcohol, and CHCl3). The copper additive was confirmed to simultaneously promote the reaction in three pathways: oxidant cracking, single electron transfer, and alcoholysis. By means of this protocol, various functionalized furancarboxylates and other heteroarenecarboxylates were facilely obtained in moderate to good yields.
- Jiang, Huanfeng,Jiang, Kai,Li, Yingwei,Luo, Wenkun,Yin, Biaolin
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supporting information
(2020/03/04)
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- Method for removing sulfinyl group in heteroaryl compound
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The invention discloses a method for removing a sulfinyl group in a heteroaryl compound. The method is characterized in that a heteroaryl cyclic sulfoxide compound represented by formula (Ia) or formula (Ib) and trimethylsilylphenyl trifluoromethanesulfonate represented by formula (II) used a substrate are reacted in the presence of cesium fluoride to obtain a sulfinyl group-removed heteroaryl compound represented by formula (IIIa) or (IIIb). The method can rapidly remove the sulfinyl group in the heteroaryl cyclic sulfoxide compound, does not need a metal catalyst with poor safety or highly toxic organic reagents, and is safe. The method has the advantages of mild conditions, strong compatibility with some sensitive benzenesulfonyl groups and Boc groups, simplicity in post-treatment, andsuitableness for industrial production.
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Paragraph 0057-0060
(2019/10/01)
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- A fast and practical synthesis of tert-butyl esters from 2-tert-butoxypyridine using boron trifluoride·diethyl etherate under mild conditions
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A practical direct preparation of tert-butyl esters from 2-tert-butoxypyridine has been developed. This system features the use of boron trifluoride·diethyl etherate in toluene solvent to rapidly achieve the reaction at room temperature. Using this reaction protocol, a variety of tert-butyl esters were synthesized from several different carboxylic acids at high yields. This practical procedure provides a promising and effective approach to the protection of carboxylic acids with a tert-butyl group.
- La, Minh Thanh,Kim, Hee-Kwon
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p. 3748 - 3754
(2018/05/28)
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- Copper-catalyzed oxidative esterification of aldehydes with dialkyl peroxides: Efficient synthesis of esters of tertiary alcohols
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Copper-catalyzed oxidative esterification of aldehydes with dialkyl peroxides has been developed. This protocol affords a novel approach for the synthesis of carboxylic esters of tertiary alcohols under mild conditions. Depending on the catalyst system, a variety of tertiary esters were produced in good to excellent yields.
- Zhu, Yefeng,Wei, Yunyang
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p. 13668 - 13670
(2013/08/23)
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- TFFH as an excellent reagent for acylation of alcohols, thiols and dithiocarbamates
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A convenient and easy procedure to synthesize esters and thioesters from the corresponding carboxylic acid using TFFH as the coupling reagent is described. The preparation of N-acyl-dithiocarbamates from carboxylic acids and 1,3-thiazolidine-2-thione with TFFH as the coupling reagent is also described.
- Pittelkow, Michael,Kamounah, Fadhil S.,Boas, Ulrik,Pedersen, Brian,Christensen, Jorn B.
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p. 2485 - 2492
(2007/10/03)
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- Mild and efficient method for preparation of tert-butyl esters
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Aliphatic and aromatic methyl esters undergo efficient transesterification at ambient temperature with potassium tert-butoxide in diethyl ether.
- Vasin,Razin
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p. 658 - 660
(2007/10/03)
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- Convenient preparations of t-butyl esters and ethers from t-butanol
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A one-pot preparation of t-butyl esters and ethers is described that proceeds from the carboxylic acid or alcohol and t-butanol using only anhydrous magnesium sulfate and catalytic sulfuric acid as additional reagents. The method affords t-butyl esters and ethers in good yields and is applicable to a variety of substrates.
- Wright, Stephen W.,Hageman, David L.,Wright, Ann S.,McClure, Lester D.
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p. 7345 - 7348
(2007/10/03)
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