- Carboxylic Acid Deoxyfluorination and One-Pot Amide Bond Formation Using Pentafluoropyridine (PFP)
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This work describes the application of pentafluoropyridine (PFP), a cheap commercially available reagent, in the deoxyfluorination of carboxylic acids to acyl fluorides. The acyl fluorides can be formed from a range of acids under mild conditions. We also demonstrate that PFP can be utilized in a one-pot amide bond formation via in situ generation of acyl fluorides. This one-pot deoxyfluorination amide bond-forming reaction gives ready access to amides in yields of ≤94%.
- Brittain, William D. G.,Cobb, Steven L.
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supporting information
p. 5793 - 5798
(2021/08/01)
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- Mechanically induced solvent-free esterification method at room temperature
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Herein, we describe two novel strategies for the synthesis of esters, as achieved under high-speed ball-milling (HSBM) conditions at room temperature. In the presence of I2 and KH2PO2, the reactions afford the desired esterification derivatives in 45% to 91% yields within 20 min of grinding. Meanwhile, using KI and P(OEt)3, esterification products can be obtained in 24% to 85% yields after 60 min of grinding. In addition, the I2/KH2PO2 protocol was successfully extended to the late-stage diversification of natural products showing the robustness of this useful approach. Further application of this method in the synthesis of inositol nicotinate was also discussed. This journal is
- Zheng, Lei,Sun, Chen,Xu, Wenhao,Dushkin, Alexandr V.,Polyakov, Nikolay,Su, Weike,Yu, Jingbo
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p. 5080 - 5085
(2021/02/05)
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- Copper-mediated simple and direct aerobic oxidative esterification of arylacetonitriles with alcohols/phenols
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A simple and direct aerobic oxidative esterification reaction of arylacetonitriles with alcohols/phenols is achieved in the presence of a copper salt and molecular oxygen, which produces a broad range of aryl carboxylic acid esters in good to high yields. Copper salt plays multiple roles in the transformation, which allows the oxygenation of C-H bond, cleavage of inert C-C bond, and formation of C-O bond in one pot without the assistance of any of the acids, bases, ligands, and so on. The reaction provides a simple, direct, and efficient protocol towards functionalized esters, especially aryl benzoates, from readily available starting materials.
- Dong, Jianyu,Chen, Xiuling,Ji, Fangyan,Liu, Lixin,Su, Lebin,Mo, Min,Tang, Jian-Sheng,Zhou, Yongbo
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- Substrate hydrophobicity and enzyme modifiers play a major role in the activity of lipase from: Thermomyces lanuginosus
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Lipase from Thermomyces lanuginosus (TL) displays high affinity for long-chain substrates, such as triolein and other long-chain triacylglycerols. Aiming to broaden the substrate chain-length specificity, different aldehydes (naphthaldehyde, butyraldehyde, hexyl aldehyde and dodecyl aldehyde) and naphthyl isothiocyanate were grafted onto lipase TL through lysine coupling. The catalytic activity of the modified lipases was investigated by reaction with substrates differing in the aliphatic chain size (p-nitrophenyl benzoate, p-nitrophenyl acetate, p-nitrophenyl butyrate, p-nitrophenyl hexanoate, p-nitrophenyl octanoate, p-nitrophenyl laurate and p-nitrophenyl palmitate). The enzymes modified with aldehydes revealed higher activity than the enzymes modified with the isothiocyanate. The most notable results were achieved for lipase TL grafted with 4 units of a dodecyl chain (TL5), which revealed the highest activity against all the tested substrates, being 10-fold more active than the native enzyme for smaller substrates (acetate and butyrate chains) and 2-fold for longer substrates (laurate and palmitate chains). The kinetic parameters evaluated (Vmax, KM and kcat/KM) also confirmed the significant catalytic performance of TL5 compared to the native enzyme. The increase in activity revealed by the modified lipases was directly proportional to the size and hydrophobicity of the linkers' aliphatic chain. Small conformational changes, either on the enzyme's lid or on the cavity of the active site were suggested by molecular dynamics simulations, circular dichroism and fluorescence spectroscopy. Moreover, the grafting with aldehydes or with the isothiocyanate conferred higher thermostability to the lipase. The chemical surface modification developed efficiently improved the activity of lipase TL, broadening the substrate's chain-length specificity, increasing thereafter the substrate possibilities for industrial reactions. This journal is
- Castro, Tarsila G.,Cavaco-Paulo, Artur,Noro, Jennifer,Silva, Carla
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p. 5913 - 5924
(2020/10/08)
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- Supramolecular Pd(II) complex of DPPF and dithiolate: An efficient catalyst for amino and phenoxycarbonylation using Co2(CO)8 as sustainable C1 source
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Highly active, efficient and robust “dppf ligated tetranuclear palladium dithiolate complex” was synthesized and applied as a catalyst for chemical fixation of carbon monoxide for the synthesis value added chemicals such as tertiary amide and aromatic esters. The synthesized catalyst was characterized using different analytical techniques such as elemental analysis, 1H and 31P NMR spectroscopy. The use of Co2(CO)8 as a cheap, less toxic and low melting solid surrogate are additional advantages over the current protocol. The catalyst showed superior activity towards the Amino (10?3 mol % catalyst) and Phenoxycarbonylation (10-2 mol % catalyst) and high TON (104 to 103) and TOF (103 to 102 h-1). The Betol and Lintrin (active drug molecules) were synthesized under an optimized reaction condition. The scalability of the current protocol has been demonstrated up-to the gram level.
- Gaikwad, Vinayak V.,Mane, Pravin A.,Dey, Sandip,Patel, Divya,Bhanage, Bhalchandra M.
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- Tropolonate salts as acyl-transfer catalysts under thermal and photochemical conditions: Reaction scope and mechanistic insights
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Acyl-transfer catalysis is a frequently used tool to promote the formation of carboxylic acid derivatives, which are important synthetic precursors and target compounds in organic synthesis. However, there have been only a few structural motifs known to efficiently catalyze the acyl-transfer reaction. Herein, we introduce a different acyl-transfer catalytic paradigm based on the tropolone framework. We show that tropolonate salts, due to their strong nucleophilicity and photochemical activity, can promote the coupling reaction between alcohols and carboxylic acid anhydrides or chlorides to give products under thermal or blue light photochemical conditions. Kinetic studies and density functional theory calculations suggest interesting mechanistic insights for reactions promoted by this acyl-transfer catalytic system.
- Mai, Binh Khanh,Koenigs, Rene M.,Nguyen, Thanh Vinh,Lyons, Demelza J.M.,Empel, Claire,Pace, Domenic P.,Dinh, An H.
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p. 12596 - 12606
(2020/11/18)
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- Selectivity in the photo-fries rearrangement of some aryl benzoates in green and sustainable media. Preparative and mechanistic studies
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Irradiation of a series of p-substituted aryl benzoates under N2 atmosphere in homogeneous and micellar media was investigated by means of steady-state condition and of time-resolved spectroscopy. A notable selectivity in favor of the 2-hydroxybenzophenone derivatives was observed in micellar media. The benzophenone derivatives were the main photoproduct. On the other hand, in homogeneous media (cyclohexane, acetonitrile, and methanol) the observed product distribution was entirely different, viz. substituted 2-hydroxybenzophenones, p-substituted phenols, benzyl and benzoic acid were found. The binding constants in the surfactant were also measured and NOESY experiments showed that the aryl benzoates were located in the hydrophobic core of the micelle. Laser flash photolysis experiments led to the characterization of both p-substituted phenoxy radical and substituted 2-benzoylcyclohexadienone transients in homogeneous and micellar environment.
- Siano, Gastón,Bonesi, Sergio M.,Crespi, Stefano,Mella, Mariella
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p. 4338 - 4352
(2019/05/01)
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- Practical and efficient synthesis of hydroxyaryl ketones catalyzed by HF@SiO2 under solvent-free condition
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A wide variety of hydroxyaryl ketones bearing different motifs was successfully synthesized with good yields and excellent selectivities in the presence of HF@SiO2 as an environmental friendly acid under solvent-free condition. Mild and green reaction conditions and excellent yields (50-91%) make this method an attractive method for the efficient synthesis of hydroxyaryl ketones. Fries rearrangement of phenyl benzoate in the presence of HF@SiO2 led to p-hydroxybenzophenone, while phenyl acetate in the same conditions produced o-hydroxyacetophenone as a single isomer.
- Paghandeh, Hossein,Saeidian, Hamid,Ghaffarzadeh, Mohammad
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p. 809 - 814
(2018/09/26)
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- Transition-Metal-Free Esterification of Amides via Selective N-C Cleavage under Mild Conditions
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A general, transition-metal-free, and operationally simple method for esterification of amides by a highly selective cleavage of N-C(O) bonds under exceedingly mild conditions is reported. The reaction is characterized by broad substrate scope and excellent functional group tolerance. The potential of this mild esterification is highlighted by late-stage diversification of natural products and pharmaceuticals. Conceptually, the metal-free acyl functionalization of amides represents a significant step forward as a practical alternative to ligand exchange in acylmetal intermediates.
- Li, Guangchen,Lei, Peng,Szostak, Michal
-
supporting information
p. 5622 - 5625
(2018/09/25)
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- Amidation and esterification of carboxylic acids with amines and phenols by N,N′-diisopropylcarbodiimide: A new approach for amide and ester bond formation in water
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The present study reports the successful synthesis of two important and abundant functional groups “ester and amide” by N,N′-diisopropylcarbodiimide (DIC) in water as a green solvent. A wide range of substrates could be employed with high functional group tolerance. The products were obtained in high yields after short reaction times. This method provides an efficient, economic, simple and very mild protocol for ester and amide bond formation in aqueous media. In addition, this work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.
- Fattahi, Nadia,Ayubi, Morteza,Ramazani, Ali
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p. 4351 - 4356
(2018/07/13)
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- Electrodimerization of N-Alkoxyamides for Zinc(II) Catalyzed Phenolic Ester Synthesis under Mild Reaction Conditions
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An electrochemical On-Off method for phenolic ester synthesis from N-alkoxyamides has been reported. This one-pot protocol begins with rapid and selective electrodimerization of the amide using n-Bu4NI (TBAI) as an electrocatalyst. The reaction proceeds further in the absence of current via Zn catalyzed C?N bond activation of the amide dimer followed by its coupling with phenol to form the ester. The present methodology is ligand-free and takes place under mild reaction conditions. This transformation incorporates a wide variety of phenols and amide substrates leading to the formation of functionalized esters highlighting its versatility. (Figure presented.).
- Subramanian, Kripa,Yedage, Subhash L.,Bhanage, Bhalchandra M.
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p. 2511 - 2521
(2018/05/14)
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- Postsynthetic modification of bacterial peptidoglycan using bioorthogonal n-acetylcysteamine analogs and peptidoglycan o-acetyltransferase B
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Bacteria have the natural ability to install protective postsynthetic modifications onto its bacterial peptidoglycan (PG), the coat woven into bacterial cell wall. Peptidoglycan O-acetyltransferase B (PatB) catalyzes the O-acetylation of PG in Gram (-) bacteria, which AIDS in bacterial survival, as it prevents autolysins such as lysozyme from cleaving the PG. We explored the mechanistic details of PatB's acetylation function and determined that PatB has substrate specificity for bioorthgonal short N-acetyl cysteamine (SNAc) donors. A variety of functionality including azides and alkynes were installed on tri-N-acetylglucosamine (NAG)3, a PG mimic, as well as PG isolated from various Gram (+) and Gram (-) bacterial species. The bioorthogonal modifications protect the isolated PG against lysozyme degradation in vitro. We further demonstrate that this postsynthetic modification of PG can be extended to use click chemistry to fluorescently label the mature PG in whole bacterial cells of Bacillus subtilis. Modifying PG postsynthetically can aid in the development of antibiotics and immune modulators by expanding the understanding of how PG is processed by lytic enzymes.
- Wang, Yiben,Lazor, Klare M.,DeMeester, Kristen E.,Liang, Hai,Heiss, Tyler K.,Grimes, Catherine L.
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supporting information
p. 13596 - 13599
(2017/11/06)
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- Metal-Free O-Arylation of Carboxylic Acid by Active Diaryliodonium(III) Intermediates Generated in situ from Iodosoarenes
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The metal-free arylative coupling of carboxylic acids using iodosoarenes without the use of a catalyst and base, which is applicable to even a highly-polar molecule bearing multiple alcohol groups, is reported. The in situ preparation of the reactive diaryliodonium(III) carboxylates is the important key to this approach, and the introduction of the trimethoxybenzene auxiliary enables both the smooth salt formations and the selective aryl transfer events during the couplings. (Figure presented.).
- Dohi, Toshifumi,Koseki, Daichi,Sumida, Kohei,Okada, Kana,Mizuno, Serina,Kato, Asami,Morimoto, Koji,Kita, Yasuyuki
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p. 3503 - 3508
(2017/09/13)
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- Sodium cyanide-promoted copper-catalysed aerobic oxidative synthesis of esters from aldehydes
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A simple and efficient copper-catalysed procedure for oxidative esterification of aldehydes with alcohols and phenols mediated by sodium cyanide, using air as a clean oxidant, is described. A variety of aromatic aldehydes and structurally different alcohols and phenols reacted efficiently, and the product esters were obtained in good to excellent yields under normal atmospheric and solvent-free conditions.
- Nowrouzi, Najmeh,Abbasi, Mohammad,Bagheri, Maryam
-
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- Transition-Metal-Free Poly(thiazolium) Iodide/1,8-Diazabicyclo[5.4.0]undec-7-ene/Phenazine-Catalyzed Esterification of Aldehydes with Alcohols
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Poly(3,4-dimethyl-5-vinylthiazolium) iodide was used as a polymer precatalyst in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and phenazine for the oxidative esterification of aldehydes with alcohols. Selective functionalization of OH groups was achieved in the presence of NH2 groups. The poly(thiazolium) iodide/DBU/phenazine system exhibited excellent catalytic activity and could be reused five times without loss of activity.
- Chun, Supill,Chung, Young Keun
-
supporting information
p. 3787 - 3790
(2017/07/26)
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- Ph3P-I2 mediated aryl esterification with a mechanistic insight
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In order to better understand the reaction mechanism and to obtain optimal conditions, the Ph3P-I2/Et3N mediated aryl esterification reaction was thoroughly investigated. Using a specific reagent addition sequence, the reaction proceeds remarkably well especially with acidic substrates. 31P NMR studies revealed that the formation of an aryloxyphosphonium salt is crucial in governing the reaction path toward the formation of phenolic esters.
- Phakhodee, Wong,Duangkamol, Chuthamat,Pattarawarapan, Mookda
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supporting information
p. 2087 - 2089
(2016/04/26)
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- Preparation of fluorous Yamaguchi reagents and evaluation of their reactivity in esterification
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Fluorous Yamaguchi (FY) reagents bearing a perfluoroalkyl chain were prepared and employed in esterification reactions; the yields were similar to those obtained with the traditional Yamaguchi (TY) reagent. Fluorous benzoic acids derived from the FY reagents were separated easily after the reaction. GC analysis revealed that the initial rates of reaction with the FY reagents were higher than those with the TY reagent. The acidities of benzoic acids produced from the FY and TY reagents were predicted by DFT to be similar (1.20 and 0.96, respectively).
- Nishio, Yuya,Kawazu, Akari,Hirano, Shun,Matsubara, Hiroshi
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p. 720 - 725
(2016/01/15)
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- The heteropolyacid catalyzed phenol method for synthesizing Arylester
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The invention discloses a synthesis method of phenol by aromatic esterification by using heteropoly acid as a catalyst. The method comprises the following steps: adding fatty acid substituted phenol ester I, substituted benzoic acid II, reaction solvent and heteropoly acid into a reaction vessel provided with a thermometer, a water separator and a stirrer, reacting at 110-170 DEG C for 0.5-10 hours, wherein the reaction progress is monitored by TLC (thin layer chromatography) in the reaction process; and after the reaction is finished, centrifuging the reaction solution, taking the supernate, washing to remove the solvent, and carrying out recrystallization or column chromatography on the crude product to obtain the aromatic ester compound III. By using the heteropoly acid as the catalyst, compared with the traditional esterification reaction, the method disclosed by the invention has the advantages of simple after-treatment, and low pollution and environment friendliness due to use of a small amount of acid. The heteropoly acid is a solid acid, and can be recycled by filtration after the reaction is finished. The aromatic esterification reaction of exchanging ester with phenol is adopted to avoid the side reaction caused by high oxidation tendency of the substituted phenol in the reaction, so that the method is simpler to operate and has higher yield.
- -
-
Paragraph 0031; 0032
(2016/11/09)
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- Olefins from biomass feedstocks: Catalytic ester decarbonylation and tandem Heck-type coupling
-
With the goal of avoiding the need for anhydride additives, the catalytic decarbonylation of p-nitrophenylesters of aliphatic carboxylic acids to their corresponding olefins, including commodity monomers like styrene and acrylates, has been developed. The reaction is catalyzed by palladium complexes in the absence of added ligands and is promoted by alkali/alkaline-earth metal halides. Combination of catalytic decarbonylation and Heck-type coupling with aryl esters in a single pot process demonstrates the viability of employing a carboxylic acid as a "masked olefin" in synthetic processes. This journal is
- John, Alex,Hogan, Levi T.,Hillmyer, Marc A.,Tolman, William B.
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supporting information
p. 2731 - 2733
(2015/03/05)
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- Solid-Phase Benzoylation of Phenols and Alcohols in Microwave Reactor: An Ecofriendly Protocol
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An efficient solid-phase benzoylation of phenols and alcohols was developed under microwave irradiation. A stoichiometric amount of benzoyl chloride was sufficient to carry out the reaction. This benzoylation features short reaction time, good yields, and easy workup procedures. Furthermore, the scope of the reaction was extended to prepare 3,5-dinitrobenzoyl derivatives of alcohols.
- Chakraborty, Suchandra,Saha, Ahana,Basu, Kaushik,Saha, Chandan
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supporting information
p. 2331 - 2343
(2015/10/12)
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- A PROCESS FOR THE SYNTHESIS OF CARBOXYLIC ACID DERIVATIVES
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The present invention discloses one-pot synthesis of various carboxylic acid derivatives using copper catalyst and sodium cyanide as the cyanide source for bringing in carbonylative coupling in a single step.
- -
-
Page/Page column 7-8; 10
(2015/05/19)
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- Study on the aromatic transesterification reaction catalyzed by phosphotungstic acid
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A practical phosphotungstic acid-catalyzed aromatic transesterification reaction for the preparation of aryl benzoates has been developed. The transesterification method avoids the oxidation of the corresponding phenols to quinone compounds with easy operations, environmentally benign conditions and high yields of the products. It is noteworthy that in this process phosphotungstic acid can be reused and recycled.
- He, Hong-Qiang,Chang, Yu-Wei,Xu, Wei-Ming
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supporting information
p. 280 - 282
(2015/06/22)
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- 4-(N,N -dimethylamino)pyridine hydrochloride as a recyclable catalyst for acylation of inert alcohols: Substrate scope and reaction mechanism
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4-(N,N-Dimethylamino)pyridine hydrochloride (DMAP·HCl), a DMAP salt with the simplest structure, was used as a recyclable catalyst for the acylation of inert alcohols and phenols under base-free conditions. The reaction mechanism was investigated in detail for the first time; DMAP·HCl and the acylating reagent directly formed N-acyl-4-(N′,N′-dimethylamino) pyridine chloride, which was attacked by the nucleophilic substrate to form a transient intermediate that released the acylation product and regenerated the DMAP·HCl catalyst.
- Liu, Zhihui,Ma, Qiaoqiao,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 236 - 239
(2014/01/23)
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- Kinetic study on nucleophilic substitution reactions of 4-Nitrophenyl X-Substituted-Benzoates with potassium ethoxide: Reaction mechanism and role of K+ Ion
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A kinetic study on nucleophilic substitution reactions of 4-nitrophenyl X-substituted-benzoates (7a-i) with EtOK in anhydrous ethanol at 25.0 ± 0.1 °C is reported. The plots of pseudo-first-order rate constants (kobsd) vs. [EtOK] curve upward. Dissection of kobsd into the second-order rate constants for the reactions with the dissociated EtOV and ion-paired EtOK (i.e., kEtO-and kEtOK, respectively) has revealed that the ion-paired EtOK is more reactive than the dissociated EtOV. Hammett plots for the reactions of 7a-i with the dissociated EtOV and ion-paired EtOK exhibit excellent linear correlations with aX = 3.00 and 2.47, respectively. The reactions have been suggested to proceed through a stepwise mechanism in which departure of the leaving-group occurs after the RDS. The correlation of the kEtOK/kEtO{ ratio with the aX constants exhibits excellent linearity with a slope of V0.53. It is concluded that the ion-paired EtOK catalyzes the reaction by increasing the electrophilicity of the reaction center rather than by enhancing the nucleofugality of the leaving group.
- Kim, Song-I,Kim, Min-Young,Um, Ik-Hwan
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p. 225 - 230
(2014/02/14)
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- Nucleophilic substitution reactions of Y-Substituted-Phenyl Benzoates with Potassium Ethoxide in Anhydrous Ethanol: Reaction Mechanism and Role of K+ Ion
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Pseudo-first-order rate constants (kobsd) have been measured spectrophotometrically for the reactions of Ysubstituted-phenyl benzoates (5a-j) with potassium ethoxide (EtOK) in anhydrous ethanol at 25.0 ± 0.1 °C. The plots of kobsd vs. [EtOK] curve upward regardless of the electronic nature of the substituent Y in the leaving group. Dissection of kobsd into the second-order rate constants for the reactions with the dissociated EtOV and ion-paired EtOK (i.e., kEtO-and kEtOK, respectively) has revealed that the ion-paired EtOK is more reactive than the dissociated Et-V. The Bronsted-type plots for the reactions with the dissociated Et-V and ion-paired EtOK exhibit highly scattered points with βlg = -0.5 ± 0.1. The Hammett plots correlated with ao constants result in excellent linear correlations, indicating that no negative charge develops on the O atom of the leaving Ysubstituted-phenoxide ion in transition state. Thus, it has been concluded that the reactions with the dissociated EtOV and ion-paired EtOK proceed through a stepwise mechanism, in which departure of the leaving group occurs after the RDS, and that K+ ion catalyzes the reactions by increasing the electrophilicity of the reaction center through a four-membered cyclic TS structure.
- Kim, Song-I,Cho, Hyo-Jin,Um, Ik-Hwan
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p. 177 - 181
(2014/02/14)
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- Montmorillonite K10 and KSF clays as acidic and green catalysts for effective esterification of phenols and alcohols under MWI
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Montmorillonite K-10 and KSF clays catalyze esterification of phenols and alcohols under microwave irradiation and solvent-free conditions in high yields within seconds.
- Marvi,Fekri,Takhti
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p. 1837 - 1840
(2015/01/09)
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- Ligand-free palladium-catalyzed aerobic oxidative coupling of carboxylic anhydrides with arylboronic acids
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We report a new, effective and environmentally friendly protocol for selective aerobic oxidative coupling of arylboronic acids with carboxylic anhydrides in the presence of ligand-free palladium catalyst. The aryl benzoates are obtained in good to excellent yields.
- Yin, Weiyan,He, Haifeng,Zhang, Yani,Long, Tong
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p. 2402 - 2406
(2014/10/15)
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- Copper(I) bromide-catalyzed carbonylative coupling of aryl halides with phenols, alcohols and amines using sodium cyanide as C1 source: A synthesis of carboxylic acid derivatives
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A new carbon monoxide-free synthesis of carboxylate derivatives via carbonylative coupling of aryl bromides with phenols, alcohols, amines and acids in the presence of copper(I) bromide as catalyst and sodium cyanide in a stoichiometric amount has been developed. Its intramolecular version provides for the preparation of lactones (e.g., isochroman-1-ones and isobenzfuranones), imides, anhydrides and lactams in excellent yields (73-96%).
- Prasad, Pragati K,Sudalai, Arumugam
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supporting information
p. 2231 - 2238
(2014/07/21)
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- Benzoyl peroxide-imidazole: A novel and efficient reagent for the mild conversion of alcohols or phenols into benzoates
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A very mild, one-pot, and expedient protocol for the conversion of alcohols and phenols into their corresponding benzoates using imidazole and benzoyl peroxide as a novel reagent is described.
- Nowrouzi, Najmeh,Alizadeh, Seyedeh Zahra
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p. 2412 - 2414
(2013/06/26)
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- Green and efficient method for the acylation of amines and phenols in the presence of hydrotalcite in water
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In this study a mild, efficient and environmentally friendly method has been developed for the synthesis of amides and esters in the presence of hydrotalcite in water at room temperature. Different types of amines and phenols have been used and in all cases the products were obtained in moderate to high yields after an easy work-up. This method follows the principles of green chemistry.
- Massah, Ahmad Reza,Toghyani, Mitra,Najafabadi, Batool Hojati
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p. 603 - 605,3
(2020/09/16)
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- Novel and efficient method for esterification catalyzed by 1-glycyl-3-methyl imidazolium chloride-iron (III) complex
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1-Glycyl-3-methyl imidazolium chloride-iron (III) complex [[Gmim]Cl-Fe(III)] was found to be a heterogeneous catalyst for an efficient and greener solvent free synthesis of esters by the condensation of carboxylic acids and alcohols with excellent yield at ambient temperature. This operation formulates very interesting, ecological perspective due to simple reaction condition, isolation, and purification of products. In addition, this method features reusability of catalyst, reduced waste, thus making new protocol more environmentally suitable whilst no catalyst leaching was observed. Iranian Chemical Society 2012.
- Karthikeyan, Parasuraman,Bhagat, Pundlik Rambhau,Kumar, Sellappan Senthil,Muskawar, Prashant Narayan,Aswar, Sachin Arunrao
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p. 983 - 990
(2013/02/23)
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- Ruthenium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols
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An efficient methodology to access benzoate derivatives via tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols catalyzed by ruthenium/NHC was developed. This operationally simple one-pot process uses O2 as the clean oxidant, producing esters in good to excellent yields.
- Zhang, Di,Pan, Changduo
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experimental part
p. 41 - 45
(2012/06/18)
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- Metal-free arylation of oxygen nucleophiles with diaryliodonium salts
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Phenols and carboxylic acids are efficiently arylated with diaryliodonium salts. The reaction conditions are mild, metal free, and avoid the use of halogenated solvents, additives, and excess reagents. The products are obtained in good-to-excellent yields after short reaction times. Steric hindrance is very well tolerated, both in the nucleophile and diaryliodonium salt. The scope includes ortho- and halo-substituted products, which are difficult to obtain by metal-catalyzed protocols. Many functional groups are tolerated, including carbonyl groups, heteroatoms, and alkenes. Unsymmetric salts can be chemoselectively utilized to obtain products with hitherto unreported levels of steric congestion. The arylation has been extended to sulfonic acids, which can be converted to sulfonate esters by two different approaches. With recent advances in efficient synthetic procedures for diaryliodonium salts the reagents are now inexpensive and readily available. The iodoarene byproduct formed from the iodonium reagent can be recovered quantitatively and used to regenerate the diaryliodonium salt, which improves the atom economy. Copyright
- Jalalian, Nazli,Petersen, Tue B.,Olofsson, Berit
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p. 14140 - 14149,10
(2012/12/12)
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- Aminolysis of Y-substituted-phenyl 2-methoxybenzoates in acetonitrile: Effect of the o-methoxy group on reactivity and reaction mechanism
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Second-order rate constants (kN) were measured for aminolyses of Y-substituted-phenyl 2-methoxybenzoates 2a-i and 4-nitrophenyl X-substituted-benzoates 3a-j in MeCN at 25.0 °C. The Bronsted-type plot for the reactions of 2a-i with piperidine curves downward, indicating that a change in rate-determining step (RDS) occurs. The Hammett plot for the reactions of 3a-j with piperidine consists of two intersecting straight lines, which might be taken as evidence for a change in RDS. However, the nonlinear Hammett plot has been suggested not to be due to a change in RDS but rather to the stabilization of the ground state of substrates possessing an electron-donating group (EDG) (e.g., 3a-c) through a resonance interaction, since the corresponding Yukawa-Tsuno plot exhibits an excellent linear correlation with ρ = 0.54 and r = 1.54. The ρ value found for the reactions of 3a-j in MeCN is much smaller than that reported previously for the corresponding reactions in H2O (i.e., ρ = 0.75). It is proposed that the reactions of 3a-j in MeCN proceed through a forced concerted mechanism due to instability of T± in the aprotic solvent, while the reactions of 2a-i proceed through a stepwise pathway with a stabilized T ± through an intramolecular H-bonding interaction.
- Um, Ik-Hwan,Bae, Ae Ri
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experimental part
p. 7510 - 7515
(2011/11/13)
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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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supporting information; experimental part
p. 7846 - 7859
(2011/10/12)
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- Fingerprint lipolytic enzymes with chromogenic p-nitrophenyl esters of structurally diverse carboxylic acids
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A series of structurally diverse chromogenic esters, including a new compound (4-nitrophenyl 2-methylpentanoate), has been synthesized, constituting an array of 17 substrates which could be applied to rapidly fingerprint the activity of lipases or esterases to reveal their substrates specificity and functional characteristics. Combined with genetic technology such as "data mining" and directed evolution, such fingerprints might be a promising platform for discovery of potentially useful enzymes in industrial application. The fingerprint of commercially available Lipase-B from Candida antarctica as a model enzyme was first measured to confirm the reliability of this method. Then three new enzymes mined from genomic libraries were successfully fingerprinted, revealing the functional characteristics of those enzymes. Among them, the enzyme SrfAD was founded with specific substrate preference towards cycloalkyl carboxylic esters and aromatic esters, making it more promising in synthetic utilities than other tested enzymes.
- Qian, Le,Liu, Jia-Yan,Liu, Jia-Ying,Yu, Hui-Lei,Li, Chun-Xiu,Xu, Jian-He
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experimental part
p. 22 - 26
(2012/02/06)
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- Enthalpy-entropy correlations in reactions of 2,4-dinitrophenyl benzoate with phenols in the presence of potassium hydrogen carbonate and with potassium phenoxides in dimethylformamide
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Temperature dependences of the relative reactivity of substituted phenols RC6H4OH in the presence of potassium hydrogen carbonate and of potassium phenoxides RC6H4O-K + toward 2,4-dinitrophenyl benzoate in dimethylformamide were studied using the competitive reactions technique. Correlation analysis of the relative rate constants kR/kH and differences in the activation parameters (ΔΔH{double barred pipe} and ΔΔS{double barred pipe}) of competitive reactions revealed the existence of two isokinetic series for each type of nucleophiles. The mechanism of transesterification was interpreted in terms of an approach based on analysis of the effect of substituent in the nucleophile on the activation parameters. Pleiades Publishing, Ltd., 2011.
- Khalfina,Vlasov
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experimental part
p. 845 - 854
(2011/10/19)
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- Palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols
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A palladium/NHC-catalyzed tandem benzylic oxidation/oxidative esterification of benzylic alcohols with phenols to access aryl benzoate derivatives is described. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, fluoro and bromo groups. Thus, it represents a practically alternative method to access aryl benzoate derivatives.
- Luo, Fang,Pan, Changduo,Cheng, Jiang,Chen, Fan
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supporting information; experimental part
p. 5878 - 5882
(2011/09/12)
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- Metal-free synthesis of aryl esters from carboxylic acids and diaryliodonium salts
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An efficient arylation of carboxylic acids with diaryliodonium salts has been developed, giving aryl esters in high yields within short reaction times for both aromatic and aliphatic substrates. The transition-metal-free conditions are compatible with a range of functional groups, and good chemoselectivity is observed with unsymmetric diaryliodonium salts. Furthermore, steric hindrance in the ortho positions is well tolerated both in the carboxylic acid and in the diaryliodonium salt, yielding aryl esters that cannot be obtained via other esterification protocols.
- Petersen, Tue B.,Khan, Rehan,Olofsson, Berit
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p. 3462 - 3465
(2011/08/07)
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- NHC/Iron cooperative catalysis: Aerobic oxidative esterification of aldehydes with phenols
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An NHC/iron cooperative catalytic system mediates the aerobic oxidative esterification of aldehydes with phenols. The use of equimolar amounts of reactants led to good to excellent isolated yields of esters.
- Reddy, R. Sudarshan,Rosa, Joao N.,Veiros, Luis F.,Caddick, Stephen,Gois, Pedro M. P.
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supporting information; experimental part
p. 3126 - 3129
(2011/05/12)
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- Palladium/NHC-catalyzed oxidative esterification of aldehydes with phenols
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A palladium-catalyzed oxidative esterification of aldehydes with phenols is described, using air as the clean oxidant. This reaction tolerates many functional groups, providing esters with yields ranging from moderate to excellent.
- Zhang, Manli,Zhang, Shouhui,Zhang, Guoying,Chen, Fan,Cheng, Jiang
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experimental part
p. 2480 - 2483
(2011/05/16)
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- Effect of alkali metal ions on nucleophilic substitution reactions of 4-Nitrophenyl X-substituted benzoates with alkali metal ethoxides in anhydrous ethanol
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Pseudo-first-order rate constants (kobsd) have been measured spectrophotometrically for nucleophilic substitution reactions of 4-nitrophenyl benzoate (5a), 4-nitrophenyl 4-methoxybenzoate (5b), and 4-nitrophenyl 4-hydroxybenzoate (5c) with alka
- Seo, Jin-A.,Kim, Song-I.,Hong, Yeon-Ju,Um, Ik-Hwan
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experimental part
p. 303 - 308
(2010/07/15)
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- Kinetics and mechanism of nucleophilic displacement reactions of Y-substituted phenyl benzoates with cyanide Ion
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Second-order rate constants (kCN-) have been measured for nucleophilic substitution reactions of Y-substituted phenyl benzoates (1a-r) with CN- ion in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. The Bronsted-type plot is linear with βlg = -0.49, a typical βlg value for reactions reported to proceed through a concerted mechanism. Hammett plots correlated with σo and σ-constants exhibit many scattered points. In contrast, the Yukawa-Tsuno plot for the same reaction exhibits excellent linearity with pY = 1.37 and r = 0.34, indicating that a negative charge develops partially on the oxygen atom of the leaving aryloxide in the rate-determining step (RDS). Although two different mechanisms are plausible (i.e., a concerted mechanism and a stepwise pathway in which expulsion of the leaving group occurs at the RDS), the reaction has been concluded to proceed through a concerted mechanism on the basis of the magnitude of βlg and pY values.
- Kim, Song-I,Kim, Eun-Hee,Um, Ik-Hwan
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experimental part
p. 689 - 693
(2010/08/19)
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- A simple and convenient method for preparation of carboxylic acid alkyl esters, phenolic and thioesters using chlorodiphenylphosphine/I2 and imidazole reagent system
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Condensation of carboxylic acids with alcohols, phenols and thiols proceeded smoothly to afford carboxylic acid alkyl esters, phenolic esters and thioesters by using the combination of chlorodiphenylphosphine, imidazole and molecular iodine in refluxing acetonitrile. Esterification with this mixed reagent system gave the corresponding products in excellent yields. The phosphorus-containing byproduct was simply removed from the organic phase by basic aqueous workup without the need for chromatography purification.
- Nowrouzi, Najmeh,Mehranpour, Abdol Mohammad,Rad, Javad Ameri
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experimental part
p. 9596 - 9601
(2011/01/03)
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- 5,5′-Dimethyl-3,3′-azoisoxazole as a new heterogeneous azo reagent for esterification of phenols and selective esterification of benzylic alcohols under Mitsunobu conditions
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5,5′-Dimethyl-3,3′-azoisoxazole is used as a new efficient heterogeneous azo reagent for the highly selective esterification of primary and secondary benzylic alcohols and phenols with aliphatic and aromatic carboxylic acids via Mitsunobu protocols. The reaction is highly selective for primary benzylic alcohols versus secondary ones, aliphatic alcohols and also phenols. The isoxazole hydrazine byproduct can be simply isolated by filtration and recycled to its azoisoxazole by oxidation.
- Iranpoor, Nasser,Firouzabadi, Habib,Khalili, Dariush
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supporting information; experimental part
p. 4436 - 4443
(2010/11/05)
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- Ytterbium triflate catalysed Friedel-Crafts reaction using carboxylic acids as acylating reagents under solvent-free conditions
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The Friedel-Crafts acylation of 1-naphthol and phenol derivatives with carboxylic acids were investigated by using a catalytic amount of metal-triflate, in particular Yb(OTf)3, under solvent-free conditions. Both aliphatic and aromatic carboxylic acids reacted easily to afford the corresponding hydroxyaryl ketones.
- Jin, Can,Li, Jie,Su, Weike
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experimental part
p. 607 - 611
(2011/02/26)
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- TiO2: A simple and an efficient catalyst for esterification of phenols under solvent-free condition
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In the presence of catalytic amount of titanium oxide (TiO2), without any additional solvent at 25°C, phenols are conveniently acylated by acid chlorides to get phenolic esters in excellent yields. The TiO2 powder can be reused three times after simple washing with CH2Cl 2.
- Pasha, Mohamed Afzal,Manjula, Krishnappa
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p. 597 - 600
(2008/09/19)
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- Easily prepared azopyridines as potent and recyclable reagents for facile esterification reactions. An efficient modified mitsunobu reaction
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(Chemical Equation Presented) The 2,2′-, 3,3′-, and 4,4′-azopyridines (azpy) and their alkyl pyridinium ionic liquids were studied as a new class of electron-deficient reagents for Mitsunobu esterification reactions. Among these compounds, 4,4′-azopyridine was found to be the most suitable one for esterification and thioesterification reactions. This new reagent promises to provide general and complementary solutions for separation problems in Mitsunobu reactions without restricting the reaction scope and facilitates the isolation of its hydrazine byproduct. The pyridine hydrazine byproduct can be simply recycled to its azopyridine by an oxidation reaction.
- Iranpoor, Nasser,Firouzabadi, Habib,Khalili, Dariush,Motevalli, Somayeh
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p. 4882 - 4887
(2008/09/21)
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- Investigation of a general base mechanism for ester hydrolysis in C-C hydrolase enzymes of the α/β-hydrolase superfamily: A novel mechanism for the serine catalytic triad
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Previous mechanistic and crystallographic studies on two C-C hydrolase enzymes, Escherichia coli MhpC and Burkholderia xenovorans BphD, support a general base mechanism for C-C hydrolytic cleavage, rather than the nucleophilic mechanism expected for a ser
- Li, Jian-Jun,Bugg, Timothy D. H.
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p. 507 - 513
(2008/03/28)
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