- Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols
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Relative rates for the Lewis base-mediated acylation of secondary and primary alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydride derivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate size leads to an actual acceleration of the acylation process, the effect being larger for secondary as compared to primary alcohols. Computational results indicate that acylation rates are guided by noncovalent interactions (NCIs) between the catalyst ring system and the DED substituents in the alcohol and anhydride reactants. Thereby stronger NCIs are formed for secondary alcohols than for primary alcohols.
- Mayr, Stefanie,Marin-Luna, Marta,Zipse, Hendrik
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p. 3456 - 3489
(2021/03/01)
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- Size-Induced Inversion of Selectivity in the Acylation of 1,2-Diols
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Relative rates for the Lewis base-catalyzed acylation of aryl-substituted 1,2-diols with anhydrides differing in size have been determined by turnover-limited competition experiments and absolute kinetics measurements. Depending on the structure of the anhydride reagent, the secondary hydroxyl group of the 1,2-diol reacts faster than the primary one. This preference towards the secondary hydroxyl group is boosted in the second acylation step from the monoesters to the diester through size and additional steric effects. In absolute terms the first acylation step is found to be up to 35 times faster than the second one for the primary alcohols due to neighboring group effects.
- Mayr, Stefanie,Zipse, Hendrik
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supporting information
p. 18084 - 18092
(2021/12/02)
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- TBHP/ n -Bu 4 PBr-Promoted Oxidative Cross-Dehydrogenative Coupling of Aryl Methanols: A Facile Synthesis of Symmetrical Carboxylic Anhydride Derivatives
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A transition-metal-free oxidative cross-dehydrogenative coupling reaction has been developed for the preparation of symmetrical carboxylic anhydrides through self-coupling dual C-O bond formations of aryl methanols. In the presence of a catalytic amount of tetrabutylphosphonium bromide (TBPB) as transfer agent and aqueous tert -butyl hydroperoxide (TBHP) as oxidant and reactant, methylene groups of aryl methanols were efficiently oxidized to C=O and coupled with the peroxide oxygen from TBHP to form a diverse array of symmetrical carboxylic anhydride derivatives.
- Adib, Mehdi,Pashazadeh, Rahim
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supporting information
p. 136 - 140
(2017/12/27)
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- An investigation on practical synthesis of carboxylic acid derivatives using p-toluenesulfonyl chloride
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Carboxylic acid derivatives are well recognized as important class of reagents frequently used in the preparation of a variety of fine or special chemicals such as amides, esters, peptides, drugs, and dyes. Although several methods were developed for the preparation of these compounds, many of them present difficulties, including low yield, high reaction temperature, harsh reaction conditions, tedious work-up, and incompatibility with scale-up. Methods: The synthesis of carboxylic anhydrides is developed through the reaction of carboxylic acids with TsCl in the presence of K2CO3 and acetonitrile as a solvent under ultrasound irradiation and conventional conditions. In addition, one-pot synthesis of acyl azides was carried out in the presence of produced carboxylic anhydrides and the addition of sodium azide under identical condition. Results: A series of carboxylic anhydrides and acyl azides were synthesized using TsCl under ultrasound irradiation and conventional stirring with simple procedure, mild reaction conditions, high yields, and scale-up ability without any restriction. In most cases, the reaction under ultrasound irradiation was better in both yields and the reaction times compared to the conventional method. Conclusion: A convenient method has been developed for the preparation of carboxylic anhydrides and acyl azides under ultrasound irradiation and conventional stirring. The present method is practical and a highly effective alternative for previous reports. The major advantages of this method are: (i) simplicity of the procedure (ii) high yields and high purity of product (iii) scale-up capacity without considerable limitation in conventional system. Under ultrasound irradiation short reaction times as compared to conventional method are observed; yields are comparable to or better than conventional method.
- Eskandari, Parvin,Kazemi, Foad
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p. 431 - 439
(2017/07/24)
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- Metal-free cross-dehydrogenative coupling of aryl aldehydes to give symmetrical carboxylic anhydrides promoted by the TBHP/nBu4PBr system
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A novel, efficient, and metal-free dual C–O bond formation reaction for the synthesis of carboxylic anhydrides from aryl aldehydes via cross-dehydrogenative coupling is described. Heating a mixture of aromatic aldehydes and an aqueous solution of tert-butyl hydroperoxide as oxidant in the presence of catalytic nBu4PBr in chlorobenzene at 80?°C for 3?h afforded the corresponding carboxylic anhydrides in good to excellent yields.
- Adib, Mehdi,Pashazadeh, Rahim,Rajai-Daryasarei, Saideh,Mirzaei, Peiman,Jamal Addin Gohari, Seyed
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supporting information
p. 3071 - 3074
(2016/07/06)
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- Acid anhydrides and the unexpected N,N-diethylamides derived from the reaction of carboxylic acids with Ph3P/I2/Et3N
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The formation of acid anhydrides from the phosphorous-mediated activation of carboxylic acids was investigated. Under various systems, activation of benzoic acid in the presence of base led to the formation of benzoic anhydride at different rates depending on the reactivity of the reagents. Using the Ph3P-I2/Et3N combination, most aryl acids were converted into the corresponding anhydrides in high yields within 5-10 min. However, for nitro-substituted derivatives, unexpectedly, N,N-diethylamides were isolated without anhydride formation. These results indicated the pronounced effect of substituents in governing these potential side reactions which can significantly affect the yields of acylation reactions promoted by phosphonium species.
- Phakhodee, Wong,Duangkamol, Chuthamat,Wangngae, Sirilak,Pattarawarapan, Mookda
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supporting information
p. 325 - 328
(2016/01/12)
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- Carboxylic acid anhydrides via Pd-catalyzed carbonylation of aryl halides at atmospheric CO pressure
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A convenient method has been developed, which allows for the direct transformation of aryl iodides into the corresponding carboxylic acid anhydrides via Pd-catalyzed carbonylation under atmospheric CO pressure. The Royal Society of Chemistry 2012.
- Li, Yang,Xue, Dong,Wang, Chao,Liu, Zhao-Tie,Xiao, Jianliang
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supporting information; experimental part
p. 1320 - 1322
(2012/02/04)
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- Reducing the cost, smell, and toxicity of the Barton reductive decarboxylation: Chloroform as the hydrogen atom source
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When used as solvent, chloroform was found to act as a hydrogen atom donor in Barton reductive decarboxylation reactions. Chloroform offers a substantial practical advantage over pre-existing hydrogen atom donors.
- Ko, Eun Jung,Williams, Craig M.,Savage, G. Paul,Tsanaktsidis, John
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p. 1944 - 1947
(2015/02/18)
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- Substrate activity screening: A fragment-based method for the rapid identification of nonpeptidic protease inhibitors
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A new fragment-based method for the rapid development of novel and distinct classes of nonpeptidic protease inhibitors, Substrate Activity Screening (SAS), is described. This method consists of three steps: (1) a library of N-acyl aminocoumarins with diverse, low molecular weight N-acyl groups is screened to identify protease substrates using a simple fluorescence-based assay, (2) the identified N-acyl aminocoumarin substrates are optimized by rapid analogue synthesis and evaluation, and (3) the optimized substrates are converted to inhibitors by direct replacement of the aminocoumarin with known mechanism-based pharmacophores. The SAS method was successfully applied to the cysteine protease cathepsin S, which is implicated in autoimmune diseases. Multiple distinct classes of nonpeptidic substrates were identified upon screening an N-acyl aminocoumarin library. Two of the nonpeptidic substrate classes were optimized to substrates with >8000-fold improvements in cleavage efficiency for each class. Select nonpeptidic substrates were then directly converted to low molecular weight, novel aldehyde inhibitors with nanomolar affinity to cathepsin S. This study demonstrates the unique characteristics and merits of this first substrate-based method for the rapid identification and optimization of weak fragments and provides the framework for the development of completely nonpeptidic inhibitors to many different proteases.
- Wood, Warren J. L.,Patterson, Andrew W.,Tsuruoka, Hiroyuki,Jain, Rishi K.,Ellman, Jonathan A.
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p. 15521 - 15527
(2007/10/03)
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- A Cheap, Simple and Efficient Method for the Preparation of Symmetrical Carboxylic Acid Anhydrides
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A manipulatively simple and facile one-pot procedure for the synthesis of symmetrical anhydride is reported. Treatment of carboxylic acids with tosyl chloride in K2CO3 media under solvent free conditions gives the corresponding anhydrides in good to excellent yields in a short reaction time via carboxylic sulfonic anhydride as the key intermediate.
- Kazemi, Foad,Sharghi, Hashem,Nasseri, Mohammad Ali
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p. 205 - 207
(2007/10/03)
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- PREPARATION D'ANHYDRIDES A PARTIR D'ACIDES CARBOXYLIQUES ET DE TETRACYANOETHYLENE
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Symmetrical anhydrides are easily obtained at 20-80 deg C, with good yields, by action of tetracyanoethylene on organic carboxylic acids in benzene solutions containing a heteroaromatic nitrogen base or another base.
- Voisin, Daniel,Gastambide, Bernard
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p. 1503 - 1504
(2007/10/02)
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- One-pot Synthesis of Acid Anhydrides from Acids Using N,N,N',N'-Tetramethylchloroformamidinium Chloride under Mild Conditions
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N,N,N',N'-Tetramethylchloroformamidinium chloride reacted smoothly with a variety of carboxylic and phosphoric acids in the presence of a tertiary amine to give the corresponding acid anhydrides in high yields.
- Fujisawa, Tamotsu,Tajima, Kazuhisa,Sato, Toshio
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p. 3529 - 3530
(2007/10/02)
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- Palladium-promoted One-step Synthesis of Aromatic Acid Anhydrides from Aromatic Compounds with Carbon Monoxide
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The one-step synthesis of aromatic acid anhydrides from aromatic compounds such as benzene, toluene, anisole, chlorobenzene, furan, and thiophen has been carried out using carbon monoxide, 1,2-dibromoethane, and palladium acetate
- Fujiwara, Yuzo,Kawata, Itaru,Kawauchi, Tomio,Taniguchi, Hiroshi
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p. 132 - 133
(2007/10/02)
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