- In situ synthesis of 2-allyloxy-1-methylpyridinium triflate for the allylation of carboxylic acids
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2-Allyloxypyridinium triflate is formed in situ by treating a mixture of 2-allyloxypyridine, a carboxylic acid, and toluene with methyl triflate. Subsequent warming of the reaction mixture in the presence of potassium carbonate leads to efficient formation of allyl esters in good to excellent yields.
- Strayer, Timothy A.,Culy, Caleb C.,Bunner, Matthew H.,Frank, Amie R.,Albiniak, Philip A.
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Read Online
- Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
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We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
- Topf, Christoph,Vielhaber, Thomas
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- Method for selective reduction α, β - unsaturated carbonyl compound carbon-carbon double bond (by machine translation)
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The invention discloses a method for selectively reducing carbon-carbon double bonds in α and β - unsaturated carbonyl compounds, which comprises the following steps of adding α, β - unsaturated carbonyl compounds shown in formula (I) in an electrolysis system and reducing α and β - unsaturated carbonyl compounds with carbonyl-conjugated carbon-carbon double bonds through an electrochemical cathodic reduction reaction. Compared with the reported method, the method disclosed by the invention does not use a metal catalyst and an external oxidant; and the reaction raw material and the electrolyte are low in price, nontoxic and tasteless, simple and convenient in post-treatment. (by machine translation)
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Paragraph 0087-0090
(2020/06/17)
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- Imidazolium Based Fluorous N-Heterocyclic Carbenes as Effective and Recyclable Organocatalysts for Redox Esterification
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A series of new highly fluorophilic ionic liquids (f > 110) was synthetized from 3-iodopropyltris(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane and N-alkyl imidazoles, followed by anion exchange. N-heterocyclic carbenes generated in situ from obtained imidazolium salts were employed to catalyze redox esterification (umpolung) of cinnamaldehyde with alcohols. The most effective N-methyl derivative with iodide as a counter anion was studied in detail with respect to the optimization of reaction conditions, substrate scope and recyclability. Recovery of the precatalyst was achieved using either fluorous extraction or performing the reaction in suitable fluorous biphase system with direct recycling of the fluorinated precatalyst phase. For both tested options, the catalytic activity did not significantly decrease within 5 subsequent cycles. The redox esterification was shown to proceed also in supercritical carbon dioxide (scCO2) as an alternative solvent where the activity of the fluorinated catalyst was also superior to the nonfluorinated model, while retaining the benefit of easy recycling.
- ?ervenková ??astná, Lucie,Bílková, Veronika,Cézová, Tereza,Cu?ínová, Petra,Karban, Jind?ich,?ermák, Jan,Krupková, Alena,Stra?ák, Tomá?
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p. 3591 - 3598
(2020/06/17)
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- Cobalt(II)-Catalyzed Alkoxycarbonylation of Aliphatic Amines via C-N Bond Activation
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The first cobalt-catalyzed deaminative alkoxycarbonylation reaction was described for the conversion of readily available primary alkyl amines to synthetically versatile esters with moderate to high yields. This transformation shows good functional group compatibility and can serve as a powerful tool for the modification of alkyl amine-containing complex natural products and drug molecules.
- Li, Chong-Liang,Jiang, Xuan,Lu, Liang-Qiu,Xiao, Wen-Jing,Wu, Xiao-Feng
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p. 6919 - 6923
(2019/09/07)
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- Broadly Applicable Ytterbium-Catalyzed Esterification, Hydrolysis, and Amidation of Imides
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An efficient, broadly applicable, operationally simple, and divergent process for the transformation of imides into a range of carboxylic acid derivatives under mild conditions is reported. By simply using catalytic amounts of ytterbium(III) triflate as a Lewis acid promoter in the presence of alcohols, water, amines, or N,O-dimethylhydroxylamine, a broad range of imides is smoothly and readily converted to the corresponding esters, carboxylic acids, amides, and Weinreb amides in good yields. This method notably enables an easy cleavage of oxazolidinone-based auxiliaries.
- Guissart, Céline,Barros, Andre,Rosa Barata, Luis,Evano, Gwilherm
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supporting information
p. 5098 - 5102
(2018/09/13)
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- Study of O-allylation using triazine-based reagents
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Acid-catalyzed allylating reagent 2,4,6-tris(allyloxy)-1,3,5-triazine (TriAT-allyl) and its substituted derivatives have been developed. The reaction of acid-, and alkali-labile alcohols with these reagents in the presence of a catalytic amount of trifluoromethanesulfonic acid (TfOH) afforded the corresponding allyl ethers in good yields. Reactions using these reagents with an unsymmetrically-substituted regioisometric allyl group suggested that a single isometric allylic cation species would be involved.
- Yamada, Kohei,Hayakawa, Naoko,Fujita, Hikaru,Kitamura, Masanori,Kunishima, Munetaka
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p. 112 - 115
(2017/01/06)
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- Simple Zn(II) Salts as Efficient Catalysts for the Homogeneous Trans-Esterification of Methyl Esters
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Abstract: This study aimed to optimize the zinc-catalyzed trans-esterification, and pointed to assess the effect of the solvent, the catalyst, its loading and the nature of the substrate. The screening disclosed the remarkable ability of zinc(II) acetate to promote the reaction in refluxing toluene at low catalyst loading. A significant improvement ensued with respect to recently results on the same reactions, in terms of less restrictive conditions and more convenient catalyst precursors. Graphical Abstract: [Figure not available: see fulltext.]
- Cucciolito, Maria E.,Lega, Matteo,Papa, Veronica,Ruffo, Francesco
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p. 1113 - 1117
(2016/06/01)
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- LED lighting as a simple, inexpensive, and sustainable alternative for Wolff rearrangements
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The Wolff rearrangement is one of the best methods for chain homologation. However, it still suffers from many drawbacks with respect to its practical execution in the laboratory. We wish to demonstrate the use of commercial LED lamps as a sustainable alternative for the classic experimental protocols typically used for Wolff rearrangements. This journal is
- Bernardim, Barbara,Hardman-Baldwin, Andrea M.,Burtoloso, Antonio C. B.
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p. 13311 - 13314
(2015/02/19)
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- Safe Removal of the Allyl Protecting Groups of Allyl Esters using a Recyclable, Low-Leaching and Ligand-Free Palladium Nanoparticle Catalyst
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A safe, facile and low-leaching (up to 0.04ppm) method has been developed for the removal of allyl, prenyl and benzyl protecting groups from the corresponding esters, using a sulfur-modified gold-supported palladium (SAPd) nanoparticle catalyst, which is known to be non-flammable. The catalyst itself was found to be recyclable and the reaction appeared to proceed on the surface of the SAPd.
- Takagi, Koji,Fukuda, Hayato,Shuto, Satoshi,Otaka, Akira,Arisawa, Mitsuhiro
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supporting information
p. 2119 - 2124
(2015/06/23)
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- Efficient direct ester condensation between equimolar amounts of carboxylic acids and alcohols catalyzed by trifluoromethanesulfonic acid (TfOH) in Solkane365mfc
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A simple, practical, and environmentally benign esterification protocol has been devised on the basis of TfOH as the catalyst and Solkane365mfc as the reaction medium. The direct condensation of equimolar amounts of various carboxylic acids and alcohols was conveniently carried out without recourse to any additional water removal technique, giving the desired carboxylic esters in excellent yields.
- Xu, Xiu-Hua,Azuma, Ayaka,Taniguchi, Misaki,Tokunaga, Etsuko,Shibata, Norio
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p. 3848 - 3852
(2013/04/23)
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- Mild, rapid, and inexpensive microwave-assisted synthesis of allylic and propargylic esters
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A variety of allylic and propargylic esters were rapidly prepared via microwave heating of their corresponding mixed anhydride derived from pivaloyl chloride. The reaction conditions were modified to account for the sterics of the alcohol and the electronics of the carboxylic acid. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Gill, Monica A.,Manthorpe, Jeffrey M.
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supporting information
p. 1460 - 1468
(2013/05/09)
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- Conjugate reduction of α,β-unsaturated carbonyl and carboxyl compounds with poly(methylhydrosiloxane) catalyzed by a silica-supported compact phosphane-copper complex
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A silica-supported, cage-type, compact phosphane (Silica-SMAP) was used for the copper-catalyzed conjugate reduction of α,β-unsaturated carbonyl and carboxyl compounds with poly(methylhydrosiloxane) (PMHS). The heterogeneous catalyst system showed high activity and chemoselectivity, and was easily separable from the reaction mixture after the reaction. Furthermore, the catalyst was reusable without loss of its high catalytic activity or selectivity.
- Kawamorita, Soichiro,Yamazaki, Kenji,Ohmiya, Hirohisa,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 3440 - 3444
(2013/02/22)
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- Chemoselective conversion of α-unbranched aldehydes to amides, esters, and carboxylic acids by NHC-catalysis
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Depending on the N-heterocyclic carbene catalyst utilized, α-unbranched aldehydes selectively provided amides, esters, or carboxylic acids through oxidation by NCS. The α-unbranched aldehyde underwent these reactions chemoselectively in the presence of an aromatic or α-branched aldehyde.
- Kuwano, Satoru,Harada, Shingo,Oriez, Raphael,Yamada, Ken-Ichi
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supporting information; experimental part
p. 145 - 147
(2012/01/12)
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- One-pot sequential synthesis of ethers from an aliphatic carboxylic acid and an alcohol by indium-catalyzed deoxygenation of an ester
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We have developed a widely applicable and direct method of etherification from a carboxylic acid and an alcohol by indium-catalyzed deoxygenation of the transient ester formed in a one-pot reaction. This simple catalytic reducing system appears to be remarkably tolerant of several functional groups including alkenes, halogens, nitro and heterocyclic groups. A reducing system composed of InBr3 and an economical hydrosiloxane, PMHS (polymethylhydrosiloxane) , enabled one-pot etherification by using a variety of aliphatic carboxylic acids and alcohols. Copyright
- Sakai, Norio,Usui, Yuta,Moriya, Toshimitsu,Ikeda, Reiko,Konakahara, Takeo
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p. 4603 - 4608
(2012/10/30)
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- α-Aroyloxyaldehydes: Scope and limitations as alternatives to α-haloaldehydes for NHC-catalysed redox transformations
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α-Aroyloxyaldehydes are readily prepared bench stable synthetic intermediates. Their ability to act as α-haloaldehyde surrogates for NHC-promoted redox esterifications and in [4+2] cycloadditions is described.
- Ling, Kenneth B.,Smith, Andrew D.
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supporting information; experimental part
p. 373 - 375
(2011/02/24)
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- Mild and catalytic transesterification reaction using K2HPO 4 for the synthesis of methyl esters
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K2HPO4 is an efficient catalyst for the transesterification reaction to produce methyl esters. Various functional groups are compatible under the mild reaction conditions. Georg Thieme Verlag Stuttgart New York.
- Shinada, Tetsuro,Hamada, Makoto,Miyoshi, Kota,Higashino, Masato,Umezawa, Taiki,Ohfune, Yasufumi
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scheme or table
p. 2141 - 2145
(2010/11/02)
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- Protic acid immobilized on solid support as an extremely efficient recyclable catalyst system for a direct and atom economical esterification of carboxylic acids with alcohols
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(Chemical Equation Presented) A convenient and clean procedure of esterification is reported by direct condensation of equimolar amounts of carboxylic acids with alcohols catalyzed by an easy to prepare catalyst system of perchloric acid immobilized on silica gel (HClO4-SiO2). The direct condensation of aryl, heteroaryl, styryl, aryl alkyl, alkyl, cycloalkyl, and long-chain aliphatic carboxylic acids with primary/secondary alkyl/cycloalkyl, allyl, propargyl, and long-chain aliphatic alcohols has been achieved to afford the corresponding esters in excellent yields. Chiral alcohol and N-t-Boc protected chiral amino acid also resulted in ester formation with the representative carboxylic acid or alcohol without competitive N-t-Boc deprotection and detrimental effect on the optical purity of the product demonstrating the mildness and chemoselectivity of the procedure. The esters of long-chain (>C10) acids and alcohols are obtained in high yields. The catalyst is recovered and recycled without significant loss of activity. The industrial application of the esterification process is demonstrated by the synthesis of prodrugs of ibuprofen and a few commercial flavoring agents. Other protic acids such as H2SO4, HBr, TfOH, HBF4, and TFA that were adsorbed on silica gel were less effective compared to HClO4-SiO2 following the order HClO4-SiO 2 ? H2SO4-SiO2 > HBr-SiO 2 > TfOH-SiO2 ? HBF4-SiO2 ≈ TFA-SiO2. When HClO4 was immobilized on other solid supports the catalytic efficiency followed the order HClO4-SiO 2 > HClO4-K10 > HClO4-Al 2O3 (neutral) > HClO4-Al2O 3 (acidic) > HClO4-Al2O3 (basic).
- Chakraborti, Asit K.,Singh, Bavneet,Chankeshwara, Sunay V.,Patel, Alpesh R.
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supporting information; experimental part
p. 5967 - 5974
(2009/12/24)
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- Triphenylphosphine dibromide: a simple one-pot esterification reagent
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We report a one-pot, expedient protocol for the conversion of carboxylic acids to their esters using excess triphenylphosphine dibromide, base, and the alcohol. The reaction gave the esterified product in moderate-to-high yields (30-95%). For chiral acids, the reaction proceeded with little or no racemization. Use of a chiral alcohol in this transformation gave the ester with retention of configuration of the stereogenic center. Information is presented indicating that esterification proceeds through the intermediate generation of an acyloxyalkoxyphosphorane and where steric interactions play an important role in the energetics of the reaction.
- Salomé, Christophe,Kohn, Harold
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supporting information; experimental part
p. 456 - 460
(2009/04/06)
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- Potassium phosphate / benzyltriethylammonium chloride as efficient catalytic system for transesterification
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Potassium phosphate (K3PO4) in the presence of benzyltriethylammonium chloride have been found to catalyses the transesterifications of a wide variety of aliphatic and aromatic esters with primary and secondary alcohols affording the corresponding esters in good-to-excellent yields.
- Cepanec, Ivica,Zivkovic, Andreja,Bartolincic, Anamarija,Mikuldas, Hrvoje,Litvic, Mladen,Merkas, Sonja
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experimental part
p. 519 - 523
(2010/01/07)
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- Transesterification of various methyl esters under mild conditions catalyzed by tetranuclear zinc cluster
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(Chemical Equation Presented) A new catalytic transesterification promoted by a tetranuclear zinc cluster was developed. The mild reaction conditions enabled the reactions of various functionalized substrates to proceed in good to high yield. A large-scale reaction under solvent-free conditions proceeded with a low E-factor value (0.66), indicating the high environmental and economical advantage of the present catalysis.
- Iwasaki, Takanori,Maegawa, Yusuke,Hayashi, Yukiko,Ohshima, Takashi,Mashima, Kazushi
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p. 5147 - 5150
(2008/09/21)
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- A versatile, practical, and inexpensive reagent, pyridine-3-carboxylic anhydride (3-PCA), for condensation reactions
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A highly useful method for the preparation of carboxylic esters and carboxamides from various carboxylic acids was established by using a novel condensing reagent, pyridine-3-carboxylic anhydride (3-PCA), in the presence of 4-(dimethylamino)pyridine as an activator. The reactions of various carboxylic acids with nucleophiles, such as alcohols or amines, afforded the corresponding carboxylic acids or carboxamides in good to high yields under mild conditions by using simple experimental procedure. In addition, it was confirmed that this protocol was applicable to a gram-scale synthesis and the by-products, including pyridine-3-carboxylic acid and pyridine-3-carboxylate (or pyridine-3- carboxamide) produced in situ, were easily removed by using a simple aqueous workup.
- Funasaka, Setsuo,Mukaiyama, Teruaki
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experimental part
p. 148 - 159
(2009/04/06)
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- [IrCl(cod)]2-catalyzed direct oxidative esterification of aldehydes with alcohols
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[IrCl(cod)]2 catalyzed the oxidative esterification of a variety of aldehydes with methanol as a solvent in combination with K2CO3 under mild conditions (rt, 12 h). The oxidative esterification reaction of aliphatic aldehydes also took place with olefinic alcohols as reagents in toluene under similar conditions.
- Kiyooka, Syun-ichi,Wada, Yosuke,Ueno, Mahuyu,Yokoyama, Takeshi,Yokoyama, Reiko
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p. 12695 - 12701
(2008/03/14)
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- Pyridine-3-carboxylic anhydride (3-PCA): A versatile, practical, and inexpensive reagent for condensation reaction between carboxylic acids and alcohols
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A synthesis of carboxylic esters from various carboxylic acids and alcohols is successfully carried out by using a condensation reagent, pyridine-3-carboxylic anhydride (3-PCA). This reaction materialized synthesis of various carboxylic esters to be carried out under mild conditions by simple experimental procedure. Copyright
- Mukaiyama, Teruaki,Funasaka, Setsuo
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p. 326 - 327
(2008/02/04)
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- Reaction of dicarbonates with carboxylic acids catalyzed by weak Lewis acids: General method for the synthesis of anhydrides and esters
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The reaction between carboxylic acids (RCOOH) and dialkyl dicarbonates [(R1OCO)2O], in the presence of a weak Lewis acid such as magnesium chloride and the corresponding alcohol (R1OH) as the solvent, leads to the esters RCOOR1 in excellent yields. The mechanism involves a double addition of the acid to the dicarbonate, affording a carboxylic anhydride [(RCO)2O], R1OH and carbon dioxide. The esters arise from the attack of the alcohols on the anhydrides. Exploiting the lesser reactivity of tert-butyl alcohol in comparison with other alcohols, a clean synthesis of both carboxylic anhydrides and esters has been set up. In the former reaction, an acid/Boc2O molecular ratio of 2:1 leads to the anhydride in good to excellent yields, depending on the stability of the resulting anhydride to the usual workup conditions. In the latter reaction, stoichiometric mixtures of the acid and Boc2O are allowed to react with a twofold excess of a primary alcohol, secondary alcohol or phenol (R 2OH) to give the corresponding esters (RCOOR2). Purification of the products is particularly easy since all byproducts are volatile or water soluble. A very easy chromatography is required only in the case of nonvolatile alcohols. A broad variety of sensitive functional groups is tolerated on both the acid and the alcohol, in particular a high chemoselectivity is observed. In fact, no transesterification processes occur with the acid-sensitive acetoxy group and methyl esters. Georg Thieme Verlag Stuttgart.
- Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Dalpozzo, Renato,Marcantoni, Enrico,Melchiorre, Paolo,Sambri, Letizia
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p. 3489 - 3496
(2008/09/19)
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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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- A facile, catalytic and environmentally benign method for esterification of carboxylic acids and transesterification of carboxylic esters with nearly equimolar amounts of alcohols
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A practical and green chemical process for the esterification of carboxylic acids with alcohols and transesterification of carboxylic esters in good to excellent yields by using K5CoW12O14· 3H2O (0.1 mol%) as catalyst is reported. The catalyst exhibited remarkable reusable activity. Georg Thieme Verlag Stuttgart.
- Bose, D. Subhas,Satyender, Apuri,Das, A. P. Rudra,Mereyala, Hari Babu
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p. 2392 - 2396
(2008/02/08)
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- A facile direct conversion of aldehydes to esters and amides using acetone cyanohydrin
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Aromatic aldehydes with electron-withdrawing groups undergo rapid reactions with a variety of alcohols and secondary amines to afford the corresponding esters and amides, respectively, in high yields, when treated with NaCN or acetone cyanohydrin and base under ambient reaction conditions. In case of α,β-unsaturated aldehydes, simultaneous reduction of the CC bond along with esterification occurred to produce the saturated esters in high yields.
- Raj, I. Victor Paul,Sudalai
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p. 8303 - 8306
(2007/10/03)
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- Iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols with precoordination of the double bond of alcohols to iridium
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A novel iridium-catalyzed oxidative esterification reaction of aliphatic aldehydes and olefinic alcohols in toluene was found under mild conditions of [IrCl(cod)]2 (5 mol %) in combination with K2CO 3 (10 mol %) at rt.
- Kiyooka, Syun-Ichi,Ueno, Mahuyu,Ishii, Eri
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p. 4639 - 4642
(2007/10/03)
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- Efficient method for the esterification of carboxylic acids with alcohols using di-2-thienyl carbonate promoted by catalytic amounts of DMAP and Hf(OTf)4
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Esterification of carboxylic acids with alcohols including bulky secondary ones by using an equimolar amount of di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) followed by addition of a catalytic amount of hafnium(IV) trifluoromethanesulfonate (Hf(OTf)4) afforded the corresponding esters in good to high yields. Copyright
- Oohashi, Yoshiaki,Fukumoto, Kentarou,Mukaiyama, Teruaki
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p. 190 - 191
(2007/10/03)
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- Polymer-supported O-alkylisoureas: Useful reagents for the O-alkylation of carboxylic acids
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Polymer-supported O-alkylisoureas were prepared by reaction of an alcohol with a polymer-supported carbodiimide under copper(II) catalysis. These reagents were used to transform carboxylic acids into the corresponding methyl, benzyl, allyl, and p-nitrobenzyl esters in a highly chemoselective manner in high yields and in very high purity after simple resin filtration and solvent evaporation. The reactions could be carried out using both conventional or microwave heating, with reaction times as short as 3-5 min in the latter case, without compromising yield, purity, or chemoselectivity. Unfortunately, the corresponding solid-supported tert-butyl isoureas could not be prepared.
- Crosignani, Stefano,White, Peter D.,Linclau, Bruno
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p. 5897 - 5905
(2007/10/03)
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- An Effective Use of Benzoic Anhydride and Its Derivatives for the Synthesis of Carboxylic Esters and Lactones: A Powerful and Convenient Mixed Anhydride Method Promoted by Basic Catalysts
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Various carboxylic esters are obtained at room temperature in excellent yields with high chemoselectivities from nearly equimolar amounts of carboxylic acids and alcohols using 2-methyl-6-nitrobenzoic anhydride with triethylamine by the promotion of a basic catalyst such as 4-(dimethylamino)pyridine. A variety of lactones are also prepared in high yields at room temperature from the corresponding ω-hydroxycarboxylic acids with use of 2-methyl-6-nitrobenzoic anhydride in the presence of 4-(dimethylamino)pyridine. A similar reaction occurs with triethylamine when using a catalytic amount of 4-(dimethylamino)pyridine 1-oxide as an effective promoter for the intramolecular condensation reaction. These methods are successfully applied to the synthesis of erythro-aleuritic acid lactone and an eight-membered-ring lactone moiety of octalactins A and B. The efficiency of the cyclizations is compared to those of other reported lactonizations.
- Shiina, Isamu,Kubota, Mari,Oshiumi, Hiromi,Hashizume, Minako
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p. 1822 - 1830
(2007/10/03)
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- A Convenient Protocol for the Esterification of Carboxylic Acids with Alcohols in the Presence of di-t-Butyl Dicarbonate
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Stoichiometric mixtures of carboxylic acids and primary or secondary alkyl alcohols are cleanly converted into their corresponding esters by treatment with di-t-butyl dicarbonate [(BOC)2O] in the presence of catalytic amounts of N,N′-dimethylaminopyridine (DMAP). This convenient procedure provides a general access to a broad variety of esters including those bearing highly sensitive functional groups such as phenol esters or BOC-groups. Purification of the products is particularly easy since the byproducts t-BuOH and CO2 are volatile - a great advantage over the standard DCC/DMAP method.
- Goo?en, Lukas J.,D?hring, Arno
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p. 263 - 266
(2007/10/03)
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- An effective method for the synthesis of carboxylic esters and lactones using substituted benzoic anhydrides with Lewis acid catalysts
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An efficient mixed-anhydride method for the synthesis of carboxylic esters and lactones using benzoic anhydride having electron withdrawing substituent(s) is developed by the promotion of Lewis acid catalysts. In the presence of a catalytic amount of TiCl2(ClO4)2, various carboxylic esters are prepared in high yields through the formation of the corresponding mixed-anhydrides from 3,5-bis(trifluoromethyl)benzoic anhydride and carboxylic acids. The combined catalyst consisting of TiCl 2(ClO4)2 together with chlorotrimethylsilane functions as an effective catalyst for the synthesis of carboxylic esters from free carboxylic acids and alcohols with 4-(trifluoromethyl)benzoic anhydride. Various macrolactones are prepared from the free ω-hydroxycarboxylic acids by the combined use of 4-(trifluoromethyl)benzoic anhydride and titanium(IV) catalysts together with chlorotrimethylsilane under mild reaction conditions. The lactonization of trimethylsilyl ω-(trimethylsiloxy) carboxylates using 4-(trifluoromethyl)benzoic anhydride is also promoted at room temperature in the presence of a catalytic amount of TiCl 2(ClO4)2. An 8-membered ring lactone, a synthetic intermediate of cephalosporolide D, is successfully synthesized according to this mixed-anhydride method using 4-(trifluoromethyl)benzoic anhydride by the promotion of a catalytic amount of Hf(OTf)4.
- Shiina, Isamu
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p. 1587 - 1599
(2007/10/03)
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- Polymer-supported O-benzyl and O-allylisoureas: Convenient preparation and use in ester synthesis from carboxylic acids
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Polymer-supported O-methyl, O-benzyl, and O-allyl-isoureas were prepared by copper(II)-catalyzed reaction of polymer-supported carbodiimide with the corresponding alcohols. These polymer-supported reagents were successfully employed to convert a series of carboxylic acids to methyl, benzyl, or allyl esters, in good yields. The products were obtained with high purity (>95% by NMR) after a simple resin filtration-solvent evaporation sequence.
- Crosignani, Stefano,White, Peter D.,Steinauer, Rene,Linclau, Bruno
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p. 853 - 856
(2007/10/03)
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- Fluoroalkyldistannoxane Catalysts for Transesterification in Fluorous Biphase Technology
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Novel, practical protocols of transesterification have been advanced with recourse to fluorous biphase technology. The fluoroalkyldistannoxane catalysts enable transesterification in FC-72 solvent to furnish 100% yields of the desired esters by use of reactants ester and alcohol in a 1:1 ratio. The catalysts also work in FC-72/organic solvent system as well as in toluene alone. A number of esters and alcohols bearing various functional groups are employable. The catalysts can be totally recovered and reused. More conveniently, the catalyst solution in FC-72 which is separated from the reaction mixture is directly used for the next reaction.
- Xiang, Jiannan,Orita, Akihiro,Otera, Junzo
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- A new condensation reaction for the synthesis of carboxylic esters from nearly equimolar amounts of carboxylic acids and alcohols using 2-methyl-6-nitrobenzoic anhydride
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Various carboxylic esters were obtained in excellent yields with high chemoselectivities from nearly equimolar amounts of carboxylic acids and alcohols using 2-methyl-6-nitrobenzoic anhydride with triethylamine in the presence of a catalytic amount of 4-(
- Shiina, Isamu,Ibuka, Ryoutarou,Kubota, Mari
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p. 286 - 287
(2007/10/03)
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- A practical and green chemical process: Fluoroalkyldistannoxane-catalyzed biphasic transesterification
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There is no need for the recovery of the catalyst in the fluorous biphasic transesterification catalyzed by [{Cl(C6F13CH2CH2)2 SnOSn(C6F13CH2CH2) 2Cl}2] (1; see scheme), which results in quantitative conversions and yields. An FC-72 solution of the dimeric flouroalkyldistannoxane 1 can be recycled repeatedly without having to recover the neat catalyst.
- Xiang, Jiannan,Toyoshima, Shinji,Orita, Akihiro,Otera, Junzo
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p. 3670 - 3672
(2007/10/03)
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- Esterification of carboxylic acids catalyzed by in situ generated tetraalkylammonium fluorides
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Esterification of carboxylic acids with alkyl halides can be efficiently catalyzed by tetrabutylammonium fluoride (TBAF) generated in situ from tetrabutylammonium hydrogensulfate (TBAHSO4) and KF·2H2O in THF. The general applicability and the characteristic feature of this approach has been amply demonstrated.
- Ooi, Takashi,Sugimoto, Hayato,Doda, Kanae,Maruoka, Keiji
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p. 9245 - 9248
(2007/10/03)
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- An Efficient Esterification Reaction between Equimolar Amounts of Free Carboxylic Acids and Alcohols by the Combined Use of Octamethylcyclotetrasiloxane and a Catalytic Amount of Titanium(IV) Chloride Tris(trifluoromethanesulfonate)
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Various carboxylic esters are prepared in good to high yields from equimolar amounts of free carboxylic acids and alcohols by the combined use of octamethylcyclotetrasiloxane and a catalytic amount of TiCl(OTf)3.
- Izumi, Jun,Shiina, Isamu,Mukaiyama, Teruaki
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p. 141 - 142
(2007/10/02)
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- A Useful Method for the Preparation of Carboxylic Esters from Free Carboxylic Acids and Alcohols
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Various carboxylic esters are prepared in excellent yields from nearly equimolar amounts of free carboxylic acids and alcohols at room temperature by combined use of 4-(trifluoromethyl)benzoic anhydride and a catalytic amount of active titanium(IV) salt together with chlorotrimethylsilane.
- Shiina, Isamu,Miyoshi, So,Miyashita, Mitsutomo,Mukaiyama, Teruaki
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p. 515 - 518
(2007/10/02)
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- A Novel Transesterification of Thioesters with Alcohols by an Electrochemical Activation
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Esters were synthesized from thioesters and alcohols in high yields by an electrochemical activation.Different results were obtained by the use of n-Bu4N+ I- and LiBF4 as the electrolyte.
- Yamaguchi, Masahiko,Tsukamoto, Yukiharu,Minami, Toru
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p. 1223 - 1226
(2007/10/02)
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- Oxygen Rearrangement of Molecular Ions of 3-Phenylpropionates
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The oxygen rearrangement in molecular ions of 3-phenylpropionates has been investigated with the aid of mass analyzed ion kinetic energy spectra.Elimination of an allyl radical followed by expulsion of ketene from the molecular ion of allyl 3-phenylpropionate is shown to result in formation of protonated benzaldehyde.The oxygen rearrangement has been found to be inoperative in ionized methyl 3-methyl-3-phenylbutyrate. + ions in the spectrum of the latter compound are formed by elimination of the 3-methyl substituent and subsequent methoxy migration.
- Liehr, Joachim G.,Caprioli, Richard M.,Beynon, John H.,Morgan, Roger P.,Richter, Wilhelm J.
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p. 157 - 160
(2007/10/02)
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