- Solid-Phase Synthesis of Phosphorothioate Oligonucleotides Using Sulfurization Byproducts for in Situ Capping
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Oligonucleotides containing phosphorothioate (PS) linkages have recently demonstrated significant clinical utility. PS oligonucleotides are manufactured via a solid-phase chain elongation process in which a four-reaction cycle consisting of detritylation, coupling, sulfurization, and failure sequence capping with Ac2O is repeated. In the capping step, uncoupled sequences are acetylated at the 5′-OH to stop the chain growth and control the levels of deletion, or (n-1), impurities. Herein, we report that the byproducts of commonly used sulfurization reagents react with the 5′-OH and cap the failure sequences. The standard Ac2O capping step can therefore be eliminated, and this 3-reaction cycle process affords a higher yield and higher or comparable overall purity compared to the conventional 4-reaction synthesis. This improvement results in reducing the number of reactions from ～80 to ～60 for the synthesis of a typical length 20-mer oligonucleotide. For every kilogram of an oligonucleotide intermediate synthesized, > 500 L of reagents and organic solvents is saved, and the E-factor is decreased to 1500 from ～2000.
- Yang, Jimin,Stolee, Jessica A.,Jiang, Hong,Xiao, Li,Kiesman, William F.,Antia, Firoz D.,Fillon, Yannick A.,Ng, Austen,Shi, Xianglin
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Read Online
- Heterogeneous Coupling of Phenylethyne over Cu-Mg-Al Mixed Oxides: Influence of Catalyst Composition and Calcination Temperature on Structural and Catalytic Properties
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Cu-Mg-Al mixed oxides in basic media are shown to be efficient catalysts in the oxidative coupling of phenylethyne to 1,4-diphenylbuta-1,3-diyne. Catalysts containing 33 at.% of Cu(II), related to the total metal content, with different ratios of Mg(II) and Al(III) were prepared by precipitation of metal nitrates with sodium carbonate and calcined at different temperatures. The samples were characterized by means of XRD, TEM, TG-MS, XPS, N2O titration, and N2 physisorption. The catalytic behavior was tested in n-butanol (0-0.1 M NaOH) in an autoclave under oxygen atmosphere (0.5-4 MPa) at different temperatures (303-353 K). Highest yields of 1,4-diphenylbuta-1,3-diyne (84%) were obtained with catalysts based on Cu-Mg-Al lamellar double hydroxides (LDHs). Typical selectivities to 1,4-diphenylbuta-1,3-diyne were in the range of 85-92%, depending on reaction conditions and conversion. Cu(II) on the catalyst surface was found to be crucial as a redox site in the coupling of phenylethyne. However, the mere presence of Cu(II) on the surface is not sufficient for a highly active catalyst. Cu(II) must be embedded into a specific matrix in order to exhibit high catalytic activity. The hydrotalcite-like phase (LDH) in Cu-Mg-Al catalysts provides such a matrix.
- Auer,Wandeler,Goebel,Baiker
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Read Online
- Novel Heterogeneous Route for the Coupling of Phenylethyne by a Catalyst derived from Cu-Mg-Al Hydrotalcite
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Cu-Mg-Al hydroxycarbonate, derived from Cu-Mg-Al hydrotalcite, affords yields of >80percent for the heterogeneous coupling of phenylethyne to 1,4-diphenylbuta-1,3-diyne in the presence of sodium hydroxide and oxygen.
- Auer, Stefan M.,Schneider, Michael,Baiker, Alfons
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Read Online
- Benzyne-Mediated Esterification Reaction
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A benzyne-mediated esterification of carboxylic acids and alcohols under mild conditions has been realized, which is made possible via a selective nucleophilic addition of carboxylic acid to benzyne in the presence of alcohol. After a subsequent transesterification with alcohol, the corresponding esters can be produced efficiently. This benzyne-mediated protocol can be used on the modification of Ibuprofen, cholesterol, estradiol, and synthesis of nandrolone phenylpropionate. In addition, benzyne can also be used to promote lactonization and amidation reaction.
- Li, Yang,Shi, Jiarong,Zhao, Jinlong
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supporting information
p. 7274 - 7278
(2021/10/01)
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- IrIII-Catalyzed direct syntheses of amides and esters using nitriles as acid equivalents: A photochemical pathway
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An unprecedented IrIII[df(CF3)ppy]2(dtbbpy)PF6-catalyzed simple photochemical process for direct addition of amines and alcohols to the relatively less reactive nitrile triple bond is described herein. Various amides and esters are synthesized as the reaction products, with nitriles being the acid equivalents. A mini-library of different types of amides and esters is made using this mild and efficient process, which uses only 1 mol% of photocatalyst under visible light irradiation (λ = 445 nm). The reaction strategy is also efficient for gram-scale synthesis.
- Talukdar, Ranadeep
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supporting information
p. 5303 - 5308
(2020/04/17)
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- Cross-Dehydrogenating Coupling of Aldehydes with Amines/R-OTBS Ethers by Visible-Light Photoredox Catalysis: Synthesis of Amides, Esters, and Ureas
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A straightforward synthesis of amides, ureas, and esters is reported by visible-light cross-dehydrogenating coupling (CDC) of aldehydes (or amine carbaldehydes) and amines/R-OTBS ethers by photoredox catalysis. The reaction is found to be general and high yielding. A plausible mechanistic pathway has been proposed for these transformations and is supported by appropriate controlled experiments.
- Pandey, Ganesh,Koley, Suvajit,Talukdar, Ranadeep,Sahani, Pramod Kumar
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supporting information
p. 5861 - 5865
(2018/09/21)
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- [Co(MeTAA)] Metalloradical Catalytic Route to Ketenes via Carbonylation of Carbene Radicals
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An efficient synthetic strategy towards beta-lactams, amides, and esters involving “in situ” generation of ketenes and subsequent trapping with nucleophiles is presented. Carbonylation of carbene radical intermediates using the cheap and highly active cobalt(II) tetramethyltetraaza[14]annulene catalyst [Co(MeTAA)] provides a convenient one-pot synthetic protocol towards substituted ketenes. N-tosylhydrazones are used as carbene precursors, thereby bridging the gap between aldehydes and ketenes. Activation of these carbene precursors by the metalloradical cobalt(II) catalyst affords CoIII-carbene radicals, which subsequently react with carbon monoxide to form ketenes. In the presence of a nucleophile (imine, alcohol, or amine) in the reaction medium the ketene is immediately trapped, resulting in the desired products in a one-pot synthetic protocol. The β-lactams formed upon reaction with imines are produced in a highly trans-selective manner.
- Chirila, Andrei,van Vliet, Kaj M.,Paul, Nanda D.,de Bruin, Bas
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supporting information
p. 2251 - 2258
(2018/04/09)
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- Palladium-catalyzed carbonylation of benzylic ammonium salts to amides and esters: Via C-N bond activation
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An efficient palladium-catalyzed carbonylation reaction of readily available quaternary ammonium salts with CO is reported for the first time to afford arylacetamides and arylacetic acid esters via benzylic C-N bond cleavage. This protocol features mild reaction conditions under atmospheric pressure of CO, a redox-neutral process without an additional oxidant, and a broad substrate scope for various kinds of amines, alcohols and phenols.
- Yu, Weijie,Yang, Shuwu,Xiong, Fei,Fan, Tianxiang,Feng, Yan,Huang, Yuanyuan,Fu, Junkai,Wang, Tao
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supporting information
p. 3099 - 3103
(2018/05/22)
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- SYNTHESIS OF THIOLATED OLIGONUCLEOTIDES WITHOUT A CAPPING STEP
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The invention herein describes a synthetic method for preparing thiolated oligonucleotides without needing a capping step, as the sulfurization agent caps the unreacted 5'-OH groups.
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Page/Page column 36
(2018/04/11)
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- Carboxyl activation of 2-mercapto-4,6-dimethylpyrimidine through n-acyl-4,6-dimethylpyrimidine-2-thione: A chemical and spectrophotometric investigation
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2-Mercapto-4,6-dimethylpyrimidine, as effective carboxyl activating group, has been successfully proved by converting it into respective acyl derivatives and the subsequent conversion to the amides and esters respectively using amines, amino alcohols and alcohols. The aminolysis and esterification were monitored chemically and spectrophotometrically. This paved way to establish that the above mercaptopyrimidine derivative is an efficient carboxyl activating group applicable in solid phase peptide synthesis.
- Rajan
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p. 287 - 291
(2015/01/30)
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- One-pot esterification and amide formation via acid-catalyzed dehydration and ritter reactions
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Esterification of carboxylic acid is achieved using acetonitrile as a water trap. Water liberated during esterification is consumed in cyanide hydrolysis, thereby driving the esterification to completion. Substrates having carboxylic acid and nitrile groups undergo intramolecular dehydration and rehydration to amido esters in the absence of acetonitrile. Cyano acids also undergo esterification and Ritter reaction in one pot when excess alcohol is used. For the first time, we have observed an interesting Ritter reaction of primary alcohols, leading to ester amide product in one pot. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Dawar, Pankaj,Raju, M. Bagavan,Ramakrishna, Ramesha Andagar
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supporting information
p. 836 - 846
(2014/03/21)
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- Catalytic properties and acidity of 1,2-benzenedisulfonimide and some of its derivatives. An experimental and computational study
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1,2-Benzenedisulfonimide (1) has previously been found to be an excellent and, importantly, safe Br?nsted acid catalyst. In this work we present the results of a search for derivatives of 1 that are more acidic and effective. Instead of blindly synthesizing a series of analogues, we have carried out a screening process in which the pKa of 1 and a set of its derivatives were calculated. The calculated pKa values were confirmed experimentally by carrying out determination through potentiometric titrations of some of the compounds: 1, 4-methyl and 4-nitro derivatives of 1. The calculations indicated that the dinitro and 4-nitro derivatives are among the best candidates for the synthesis. The latter was obtained in good yields and tested as a catalyst. Results were excellent as the reactions took place more quickly and at lower temperatures in all cases, and in a number of cases it was even possible to reduce the amount of catalyst.
- Barbero, Margherita,Berto, Silvia,Cadamuro, Silvano,Daniele, Pier Giuseppe,Dughera, Stefano,Ghigo, Giovanni
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p. 3212 - 3217
(2013/04/24)
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- Palladium on carbon-bromobenzene mediated esterification and transesterification
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A series of carboxylic acids were converted into their corresponding esters using the Pd/C catalyzed hydrogenation conditions in the presence of catalytic bromobenzene in alcohols and the method could also be applicable for the transesterification of esters. Good to excellent yields were obtained for different aliphatic or aromatic starting materials. The success of this esterification relies on the in situ generation of hydrobromic acid (HBr) from bromobenzene which provides a mild and acidic reaction environment. The palladium catalyst exhibits a remarkable activity and is reusable for up-to three consecutive cycles.
- Aavula, Sanjeev Kumar,Chikkulapalli, Anil,Hanumanthappa,Jyothi, Indira,Vinod Kumar,Manjunatha, Sulur G.
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p. 5690 - 5694
(2013/09/24)
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- Catalysis studies of macroreticular polystyrene cation-exchange resin with terminal perfluoroalkanesulfonic acids
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Macroreticular p-(ω-sulfonic-perfluoroalkylated) polystyrene (FPS) resin with the advantages of both sulfonic polystyrene (such as macroreticular Amberlyst-15) and perfluoroalkanesulfonic resin (such as superacidic Nafion NR50) has exhibited excellent catalytic selectivity and activity in cyclization of pseudoionone and condensation of indole. In this paper, FPS was characterized by XPS, nitrogen sorption technique, FESEM and Hammett indicator method, and employed as the solid acid catalyst in the esterification, acylation and alkylation reactions. The FPS resin showed better activity than commercial solid acid catalysts (Amberlyst-15 and Nafion NR50) owing to its high surface area and strong acidity close to superacidity.
- Lin, Zhenghuan,Guan, Chuanjin,Huang, Limei,Wang, Wen,Ling, Qidan,Zhao, Chengxue
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p. 261 - 266
(2013/07/27)
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- Synthesis of alkyl-ynol-ethers by anti-Michael addition of metal alkoxides to β-substituted alkynylsulfones
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The reaction of metal alkoxides with β-substituted 2-(p-tolylsulfonyl)acetylenes, involving an anti-Michael addition reaction followed by the in situ elimination of the sulfonyl moiety, provides a direct method for the synthesis of alkyl alkynyl ethers bearing aryl or TIPS groups joined to the triple bond. Arylalkynyl ethers derived from primary alkoxides are in situ hydrolyzed into arylacetic esters. Copyright
- Marzo, Leyre,Parra, Alejandro,Frias, Maria,Aleman, Jose,Garcia Ruano, Jose Luis
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p. 4405 - 4409
(2013/07/26)
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- Alcohol assisted C-C bond breaking: Copper-catalyzed deacetylative α-arylation of β-keto esters and amides
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A method of alcohol-assisted copper-catalyzed highly selective deacetylative α-arylation of β-keto esters and amides has been demonstrated, which illustrated an efficient example of achieving α-aryl esters and amides. From the synthetic point of view, this arylation protocol is general and practical, representing a simple way to produce α-arylated carbonyl compounds from basic starting materials at low cost.
- Ke, Jie,He, Chuan,Liu, Huiying,Xu, Huan,Lei, Aiwen
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supporting information
p. 6767 - 6769
(2013/07/26)
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- Synthesis of arylacetates from benzylic alcohols and oxalate esters through decarboxylative coupling
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Follow that dream: By combining a reversible transesterification between benzylic alcohols and dialkyl oxalates with catalytic decarboxylation of the resulting esters, a regiospecific C-C-bond-forming reaction to give α-arylacetates was achieved. In the overall process, CO2 and a volatile alcohol are the only byproducts. Various α-arylacetates were thus synthesized in high yields from easily accessible starting materials in the presence of catalytic amounts of Pd(OAc)2, dppp, and DABCO (see scheme). Copyright
- Gruenberg, Matthias F.,Goossen, Lukas J.
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supporting information
p. 7334 - 7337
(2013/06/27)
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- PROCESS FOR SYNTHESIZING PHENYLACETIC ACID BY CARBONYLATION OF TOLUENE
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A production process for substituted phenylacetic acids or ester analogues thereof is disclosed. In this process toluene or toluene substituted with various substituents, an alcohol, an oxidant and carbon monoxide are used as raw materials to obtain compounds comprising structure of phenylacetic acid ester or analogues thereof by catalysis of the complex catalyst formed from transition metal and ligand, and such compounds are hydrolyzed to obtain various substituted phenylacetic acid based compounds. This type of compounds and their derivatives serve as important fine chemicals used widely in the industries of pharmaceuticals, pesticides, perfume and the like.
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Paragraph 0036; 0037
(2013/11/19)
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- Palladium-catalyzed oxidative carbonylation of benzylic C-H bonds via nondirected C(sp3)-H activation
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A new strategy for generating benzylpalladium reactive species from toluenes via nondirected C(sp3)-H activation has been developed. This led to construction of an efficient Pd-catalyzed reaction protocol for the oxidative carboxylation of benzylic C-H bonds to form substituted 2-phenylacetic acid esters and derivatives from inexpensive, commercially available starting materials.
- Xie, Pan,Xie, Yinjun,Qian, Bo,Zhou, Han,Xia, Chungu,Huang, Hanmin
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supporting information; experimental part
p. 9902 - 9905
(2012/08/08)
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- Pd-catalyzed decarboxylative cross-couplings of potassium malonate monoesters with aryl halides
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An efficient catalytic protocol for Pd-catalyzed decarboxylative cross-coupling of potassium malonate monoesters and derivatives with aryl bromides and chlorides are described. Because of its broad applicability, this new catalytic system provides an alternative method for the preparation of diverse aryl acetic acids and derivatives.
- Feng, Yi-Si,Wu, Wei,Xu, Zhong-Qiu,Li, Yan,Li, Ming,Xu, Hua-Jian
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p. 2113 - 2120
(2012/03/26)
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- Use of diethoxymethane as a solvent for phase-transfer esterification of carboxylic acids
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The esterification of carboxylic acids with selected primary alkyl halides in diethoxymethane (DEM) utilizing solid-liquid phase-transfer catalysis has been studied. The use of DEM as the solvent simplifies the process in that a single solvent can be used for both reaction and workup.
- Coleman, M. Todd
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scheme or table
p. 1911 - 1913
(2012/06/04)
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- One-pot ester synthesis from allyl and benzyl halides and alcohols by palladium-catalyzed carbonylation
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A mild and efficient one-pot synthesis of esters based on the Pd-catalyzed alkoxy- and aryloxycarbonylation of allylic and benzylic halides is described. The methodology has been applied to primary, secondary, and tertiary alcohols as well as to phenol derivatives. The O-protection of some biologically relevant molecules is also reported. Georg Thieme Verlag Stuttgart New York.
- Tommasi, Sara,Perrone, Serena,Rosato, Francesca,Salomone, Antonio,Troisi, Luiginio
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experimental part
p. 423 - 430
(2012/03/11)
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- Alcoholysis of naturally occurring imides: Misleading interpretation of antifungal activities
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The frequent presence of the sulfur-containing amide penangin (10) in leaf extracts of Glycosmis species turned out to be the result of decomposition of imides generated by extraction and storage in MeOH. Reinvestigation of Glycosmis mauritiana and G. cf. puberula with acetone revealed the presence of six imides. In addition to penimides A (1) and B (2) and ritigalin (6), three new derivatives, krabin (4), isokrabin (5), and methoxypenimide B (3), were isolated and identified by spectroscopic methods. All six imides were shown to be susceptible to different rates of methanolic cleavage, leading to their corresponding methyl esters and sulfur-containing amides. Whereas the decomposition products penangin (10), isopenangin (11), and sinharin (14) are known, the corresponding cleavage of methyl N-methylthiocarbamate (7) from ritigalin (6), monitored in situ by 1H NMR spectroscopy, is described here for the first time. Its structure was further confirmed by GC-MS coupling. HPLC-UV comparison of many different samples of G. mauritiana, extracted with MeOH, revealed considerable chemical variations in sulfur-containing amides, strongly correlated with different antifungal potency. The lack of activity of many methanolic crude extracts can be explained by a preponderance of the inactive decomposition product penangin (10), whereas the corresponding naturally occurring imides penimides A (1) and B (2) and methoxypenimide B (3), extracted with acetone, showed high fungitoxic properties.
- Pacher, Thomas,Raninger, Adriane,Lorbeer, Eberhard,Brecker, Lothar,But, Paul Pui-Hay,Greger, Harald
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body text
p. 1389 - 1393
(2010/11/04)
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- Structure activity relationship of organic alcohol and esters for antidepressant-like activity
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The synthesized compounds 1-7 were evaluated for their antidepressant activity, among which 2-phenylethyl alcohol 1 and isoamyl phenylacetate 3 showed 43 % and 37 % reduction in immobility time in mice using forced swim test, thereby, displaying antidepressant-like activity. Compound 1 and 3 were equipotent and both these compounds were 2x effective than the standard drug phenelzine. Considering other esters it appears that a decrease in alkyl chain length or addition of either NO2 or OH groups to the phenyl ring caused a marked decline in the antidepressant-like activity.
- Perveen, Shahnaz,Yasmeen, Arfa,Khan, Muhammad Aitmaud,Dar, Ahsana,Jafri, Rehana,Ahmed, Amir
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experimental part
p. 14 - 17
(2011/01/03)
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- Oxidation of substituted β-diketones with hydrogen peroxide: Synthesis of esters through the formation of bridged 1,2,4,5-tetraoxanes
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Acid-catalyzed oxidation of alkyl- and benzyl-substituted -diketones by hydrogen peroxide at 79-120C in a mixture of an alcohol and a strong acid (sulfuric acid, tetrafluoroboric acid, or perchloric acid) gave the corresponding esters through the formation of bridged 1,2,4,5-tetraoxanes. Georg Thieme Verlag Stuttgart · New York.
- Terentev, Alexander O.,Borisov, Dmitry A.,Yaremenko, Ivan A.,Ogibin, Yuri N.,Nikishin, Gennady I.
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experimental part
p. 1145 - 1149
(2010/06/14)
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- o-benzenedisulfonimide as reusable bronsted acid catalyst for acid-catalyzed organic reactions
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Acid-catalyzed organic reactions, such as etherification, esterification, acetal synthesis, cleavage, and interconversion, and pinacol rearrangement were carried out in the presence of catalytic amounts of o-benzenedisulfonimide as Bronsted acid catalyst; the conditions were mild and selective. The catalyst was easily recovered and purified, ready to be used in further reactions, with economic and ecological advantages. Georg Thieme Verlag Stuttgart.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano,Venturello, Paolo
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p. 1379 - 1388
(2008/12/21)
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- The effect of substituents and operating conditions on the electrochemical fluorination of alkyl phenylacetates in Et3N·4HF medium
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Selective electrochemical fluorination of alkyl phenylacetates (Ph-CH2-COOR, where R is methyl, ethyl, n-propyl, n-butyl, i-propyl and sec-butyl) under galvanostatic conditions were reported in Et3N·4HF medium. Preparative electrolysis experiments were carried out both in pre-electrolysed dry Et3N·4HF and the same electrolyte medium without pre-electrolysis. Very little hydrolysed fluorinated products were obtained in pre-electrolysed medium where as significant quantities of hydrolysed products leading to fluorinated phenylacetic acid were obtained from Et3N·4HF without pre-electrolysis. Under optimum experimental conditions up to 87% selectivity of monofluoro ester could be achieved. Difluoro alkyl phenylacetate, monofluoro and difluoro phenylacetic acids were the other predominant side products obtained. The hydrolysis appears to be initiated by tautomeric transformation of proton after the initial electro oxidative formation of the cation radical. 19F as well as 1H NMR spectroscopy have been employed to identify the minor constituents formed during the electro oxidative process.
- Ilayaraja,Manivel,Velayutham,Noel
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p. 185 - 192
(2008/09/17)
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- o-benzenedisulfonimide: A novel and reusable catalyst for acid-catalyzed organic reactions
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The o-benzenedisulfonimide is used as Br?nsted acid in catalytic amounts in various acid-catalyzed organic reactions, such as etherification, esterification, and acetalization; the conditions required are mild and in the considered examples the results are always good. A useful aspect of the use of this catalyst is its easy recovery in high yield from the reaction mixture and its reuse in other reactions, with economic and ecological advantages. Georg Thieme Verlag Stuttgart.
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano,Venturello, Paolo
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p. 2209 - 2212
(2008/02/10)
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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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- Alumina sulfuric acid as a novel heterogeneous system for esterification of carboxylic acids in solvent free conditions
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Neat chlorosulfonic acid reacts with alumina to give alumina sulfuric acid (ASA) in which sulfuric acid is immobilised on the surface of alumina via a covalent bond. Carboxylic acids can be readily converted to their corresponding esters with a combination of ASA and alcohols in solvent free conditions.
- Sharghi, Hashem,Sarvari, Mona Hosseini,Eskandari, Razieh
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p. 488 - 491
(2007/10/03)
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- An eco-friendly method for the synthesis of aryl and alkyl esters of carboxylic acids using acid activated Indian bentonite
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Esterification of various carboxylic acids with phenol and alcohols has been achieved using acid activated Indian bentonite (AAIB) as catalyst. The catalyst is versatile, and the reaction is found to work well for primary, secondary and tertiary alcohols. The yields are very good under specific reaction conditions.
- Vijayakumar,Iyengar, Pushpa,Nagendrappa, Gopalpur,Prakash, B. S. Jai
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p. 922 - 925
(2007/10/03)
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- Butoxycarbonylation of aryl halides catalyzed by a silica-supported poly[3-(2-cyanoethylsulfanyl)propylsiloxane palladium] complex
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Aryl bromides and iodides react with carbon monoxide and n-butyl alcohol at 100°C and atmospheric pressure in the presence of tri-n-butylamine and a catalytic amount of a silica-supported sulfur palladium complex to form esters in moderate to good yields.
- Cai, Ming-Zhong,Song, Cai-Sheng,Huang, Xian
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p. 2273 - 2274
(2007/10/03)
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- An efficient use of zeolite catalysts for esterification of carboxylic acids
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A mild and practical method (batch process) for the esterification of carboxylic acids with alcohols using zeolite catalysts in good to excellent yields is described. The esterification of phenylacetic acid with ethanol has also been carried out in very high yield using continuous flow fixed bed reactor.
- Gumaste, Vikas K.,Deshmukh,Bhawal
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p. 1174 - 1179
(2007/10/03)
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- Hydroxylation of carbanions with lithium teri-butyl peroxide acting as an oxenoid
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The lithium salt of terf-butyl hydroperoxide can convert alkyl, vinyl, aryl carbanions, acetylides and various enolates into the corresponding hydroxylated derivatives in good yields and under mild conditions. Eisevier.
- Julia, Marc
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- Oxidation of Alkynes by Hydrogen Peroxide Catalyzed by Methylrhenium Trioxide
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The oxidation of alkynes with hydrogen peroxide is catalyzed by methylrhenium tioxide.The reactions can be rationalized by postulating that an oxirene intermediate is formed between a rhenium peroxide and the alkyne.Internal alkynes yield α-diketones and carboxylic acids, the latter from the complete cleavage of the triple bonds.Rearrangement products were observed only for aliphatic alkynes.Terminal alkynes gave carboxylic acids and their derivatives and α-keto acids as the major products, but their yields varied with the solvent used.
- Zhu, Zuolin,Espenson, James H.
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p. 7728 - 7732
(2007/10/03)
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- Mild, one-pot conversion of carboxylic acids into esters using phase transfer catalysis
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One-pot conversion of carboxylic acids into esters under the influence of phase transfer catalysis is reported.The method is shown to work satisfactorily for optically active acids having epimerisable α-hydrogen.
- Puntambekar, Hemalata M,Naik, D G,Kapadi, A H
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p. 793 - 794
(2007/10/02)
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- Process for the production of carboxylic acid esters
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Carboxylic acid esters are produced by reacting (i) carbon monoxide, (ii) a compound of the formula M(OR)x wherein M is either boron, silicon, aluminum, titanium or zirconium, x is the valency of M and R is a hydrocarbyl group and (iii) a hydrocarbyl halide, wherein the halide moiety is bromide, chloride or iodide, in the presence of a catalyst comprising one or more of the metals rhodium, iridium and cobalt in either elemental or compound form. When M is boron, silicon or aluminum and the halide moiety is chloride, there is preferably added a source of iodide.
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- Mono- and Bi-metallic Catalysed Formate-Halide Carbonylation Reactions
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Benzylic, aryl, and alkyl halides react with formate esters and carbon monoxide, in the presence of the dimer of chloro(hexa-1,5-diene)rhodium(I), 2, to give carboxylic esters: bimetallic catalysis 2> is particularly beneficial when an aromatic halide is used as the substrate.
- Buchan, Caroline,Hamel, Nathalie,Woell, James B.,Alper, Howard
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p. 167 - 168
(2007/10/02)
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- IODIDE ION PROMOTION BENZYL CHLORIDE-BORATE ESTER CARBONYLANION REACTIONS
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Esters are isolated in fine yields from the rhodium(I) catalyzed reaction of benzyl chlorides with borate esters and carbon monoxide, in the presence of potassium iodide.
- Alper, Howard,Hamel, Nathalie,Smith, David J. H.,Woell, James B.
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p. 2273 - 2274
(2007/10/02)
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- RHODIUM(I) CATALYZED CARBONYLATION REACTIONS OF HALIDES AND ETHERS
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Benzylic bromides and methyl ioide react with ethers, carbon monoxide, potassium iodide, and the dimer of chloro(1,5-hexadiene)rhodium(I) to give esters in good yields.
- Buchan, Caroline,Hamel, Nathalie,Woell, James B.,Alper, Howard
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p. 5743 - 5746
(2007/10/02)
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- SYNTHESIS OF ESTERS BY RHODIUM(I) CATALYZED BORATE ESTER-BENZYLIC BROMIDE CARBONYLATION REACTIONS
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Benzylic halides react with trialkylborates and carbon monoxide, in the presence of 1,5-hexadienerhodium chloride dimer, to give esters in excellent yields.The reaction is applicable to the synthesis of primary, secondary and even tertiary esters.
- Woell, James B.,Alper, Howard
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p. 3791 - 3794
(2007/10/02)
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- Synthesis of phenylacetic acid esters
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Esters of phenylacetic acids are prepared in a single step by hydrolysis of 2,2,2-trichloro-1-phenylethanes in inorganic basic media.
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- PALLADIUM COMPLEX-CATALYZED CARBONYLATION OF ORGANIC HALIDES IN THE PRESENCE OF CYCLIC ETHERS: HALOHYDRIN ESTER SYNTHESIS
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Cyclic ethers were cleaved by palladium complex-catalyzed carbonylation of organic halides to give halohydrin esters.
- Tanaka, Masato,Koyanagi, Masayuki,Kobayashi, Toshiaki
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p. 3875 - 3878
(2007/10/02)
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- Reaction of Lithium Dialkylcuprates with S-2-Pyridiyl Thioates in the Presence of Oxygen. A Carboxylic Ester Synthesis
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Reaction of lithium dialkylcuprates with S-2-pyridyl thioates in the presence of oxygen affords carboxylic esters in high yields, whereas under nitrogen it affords ketones.
- Kim, Sunggak,Lee, Jae In,Chung, Bong Young
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p. 1231 - 1232
(2007/10/02)
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- Process for the preparation of carboxylic acid esters from organic halides
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Carboxylic acid esters or amides are obtained from aryl, heterocyclic, vinylic, ethynylic, and benzylic halides and substituted derivates thereof, by reacting same with an alcohol or primary or secondary amine and carbon monoxide, in the presence of a palladium catalyst and if necessary a tertiary amine at about 20°-150° C and from about a half to about 100 atmospheres pressure. A typical example is the conversion of bromobenzene into n-butyl benzoate at 100° C and one atmosphere of carbon monoxide in the presence of tri-n-butyl-amine and a catalytic amount of PdBr2 [P(C6 H5)3 ]2.
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