103-38-8Relevant articles and documents
A highly selective, high-speed, and hydrolysis-free O-acylation in subcritical water in the absence of a catalyst
Sato, Masahiro,Matsushima, Keiichiro,Kawanami, Hajime,Ikuhsima, Yutaka
, p. 6284 - 6288 (2007)
(Chemical Equation Presented) Fast and furious: A wide range of alcohols are acylated by acetic anhydride, in the absence of catalyst, in subcritical water in a flow-type microreaction system. The esters are selectively produced in high yields at temperatures of 200 to 250°C. Varying the amount of acetic anhydride added with respect to the alcohols allows the regioselective acylation of one or both hydroxy groups of various dihydroxy compounds (see picture).
N-Heterocyclic Carbene/Carboxylic Acid Co-Catalysis Enables Oxidative Esterification of Demanding Aldehydes/Enals, at Low Catalyst Loading
Berkessel, Albrecht,Biswas, Animesh,Harnying, Wacharee,Sudkaow, Panyapon
supporting information, p. 19631 - 19636 (2021/08/09)
We report the discovery that simple carboxylic acids, such as benzoic acid, boost the activity of N-heterocyclic carbene (NHC) catalysts in the oxidative esterification of aldehydes. A simple and efficient protocol for the transformation of a wide range of sterically hindered α- and β-substituted aliphatic aldehydes/enals, catalyzed by a novel and readily accessible N-Mes-/N-2,4,6-trichlorophenyl 1,2,4-triazolium salt, and benzoic acid as co-catalyst, was developed. A whole series of α/β-substituted aliphatic aldehydes/enals hitherto not amenable to NHC-catalyzed esterification could be reacted at typical catalyst loadings of 0.02–1.0 mol %. For benzaldehyde, even 0.005 mol % of NHC catalyst proved sufficient: the lowest value ever achieved in NHC catalysis. Preliminary studies point to carboxylic acid-induced acceleration of acyl transfer from azolium enolate intermediates as the mechanistic basis of the observed effect.
Aerobic oxidative esterification and thioesterification of aldehydes using dibromoisocyanuric acid under mild conditions: No metal catalysts required
Kwon, Young-Do,La, Minh Thanh,Kim, Hee-Kwon
, p. 10833 - 10841 (2018/07/05)
A practical direct method for the direct preparation of esters and thioesters from aldehydes is described. Esters and thioesters were synthesized by oxidative esterification and thioesterification via in situ generated acyl bromide intermediates, which were used to react with various alcohols and thiols. The esterification and thioesterification were readily performed in the presence of dibromoisocyanuric acid in dichloromethane, without any metal catalysts and under mild conditions. By using this reaction protocol, various esters and thioesters were prepared in high yields. This effective method offers a promising approach for the facile esterification and thioesterification of aldehydes.
1,4-Bis-Dipp/Mes-1,2,4-Triazolylidenes: Carbene Catalysts That Efficiently Overcome Steric Hindrance in the Redox Esterification of α- And β-Substituted α,β-Enals
Yatham, Veera Reddy,Harnying, Wacharee,Kootz, Darius,Neud?rfl, J?rg-M.,Schl?rer, Nils E.,Berkessel, Albrecht
supporting information, p. 2670 - 2677 (2016/03/12)
As reported by Scheidt and Bode in 2005, sterically nonencumbered α,β-enals are readily converted to saturated esters in the presence of alcohols and N-heterocyclic carbene catalysts, e.g., benzimidazolylidenes or triazolylidenes. However, substituents at the α- or β-position of the α,β-enal substrate are typically not tolerated, thus severely limiting the substrate spectrum. On the basis of our earlier mechanistic studies, a set of N-Mes- or N-Dipp-substituted 1,2,4-triazolium salts were synthesized and evaluated as (pre)catalysts in the redox esterification of various α- or β-substituted enals. In particular the 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes overcome the above limitations and efficiently catalyze the redox esterification of a whole series of α/β-substituted enals hitherto not amenable to NHC-catalyzed transformations. The synthetic value of 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes is further demonstrated by the one-step bicyclization of 10-oxocitral to (racemic) nepetalactone in diastereomerically pure form.
α-Aroyloxyaldehydes: Scope and limitations as alternatives to α-haloaldehydes for NHC-catalysed redox transformations
Ling, Kenneth B.,Smith, Andrew D.
supporting information; experimental part, p. 373 - 375 (2011/02/24)
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.
Oxidation of primary aliphatic and aromatic aldehydes with difluoro(aryl)-λ3-bromane
Ochiai, Masahito,Yoshimura, Akira,Hoque, Md. Mahbubul,Okubo, Takuji,Saito, Motomichi,Miyamoto, Kazunori
supporting information; experimental part, p. 5568 - 5571 (2011/12/03)
Oxidation of primary aliphatic aldehydes with p- trifluoromethylphenyl(difluoro)-λ3-bromane in dichloromethane at 0 °C afforded acid fluorides selectively in good yields, while that of aromatic aldehydes in chloroform at room temperature produced aryl difluoromethyl ethers. A larger migratory aptitude of aryl groups compared to primary alkyl groups during a 1,2-shift from carbon to an electron-deficient oxygen atom in bromane(III) Criegee-type intermediates will result in these differences in the reaction courses.
Efficient three-step sequence for the deamination of α-aminoesters. Application to the synthesis of CysLT1 antagonists
González, Alfredo,Pérez, Daniel,Puig, Carles,Ryder, Hamish,Sanahuja, Jordi,Solé, Laia,Bach, Jordi
supporting information; experimental part, p. 2750 - 2753 (2009/09/25)
A practical and efficient three-step sequence for the deamination of α-aminoesters is reported. This method is based on the NaBH4-mediated selective reduction of α-diazoesters to α-hydrazonoesters and has been successfully applied to the deamin
Process for producing esterificated condensate
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Page 6, (2008/06/13)
The present invention provides a method for preparing ester or thioester that can conduct catalytic esterification reaction with an equimolar amount of carboxylic acid and alcohol, or catalytic thioesterification reaction with carboxylic acid and an equimolar amount or small amount of thiol, and can be expected as an industrial method that needs an enormous amount of synthesis in the light of green chemistry. By using hafnium chloride (IV), especially tetravalent hafnium compounds represented by hafnium chloride (IV)?(THF)2 or hafnium (IV)t-butoxide as a (poly) condensation catalyst, direct condensation reaction is conducted from carboxylic acid and an equimolar amount of alcohol or a little smaller amount of thiol, in the nonpolar solvent such as toluene and the like, in a deoxidization atmosphere and under heating reflux, and the reaction synthesizes ester monomer or thioester monomer, polyester or polythioester. When heating reflux is conducted by using a nonpolar solvent, it is preferable to remove azeotropic water from the reaction system.
Direct ester condensation from a 1:1 mixture of carboxylic acids and alcohols catalyzed by hafnium(IV) or zirconium(IV) salts
Ishihara, Kazuaki,Nakayama, Masaya,Ohara, Suguru,Yamamoto, Hisashi
, p. 8179 - 8188 (2007/10/03)
To promote atom efficiency in synthesis and to avoid the generation of environmental waste, the use of stoichiometric amounts of condensing reagents or excess substrates should be avoided. In esterification, excess amounts of either carboxylic acids or alcohols are normally needed. We found that the direct condensation of equimolar amounts of carboxylic acids and alcohols could be achieved using hafnium(IV) or zirconium(IV) salts. These metal salts are highly effective as catalysts for the selective esterification of primary alcohols with carboxylic acids in the presence of secondary alcohols or aromatic alcohols. The present methods can be applied to direct polyesterification and may be suitable for large-scale operations.
CHLORO- AND IODOTRIMETHYLSILANE-ACTIVATED ADDITIONS OF ORGANOCOPPER COMPOUNDS TO ENONES AND ENOATES
Bergdahl, Mikael,Lindstedt, Eva-Lotte,Nilsson, Martin,Olsson, Thomas
, p. 2055 - 2062 (2007/10/02)
Organocopper compounds add to enones and enoates in the presence of chloromethylsilane in ether giving the conjugate adducts in preparatively usefu yields via the silyl enol ethers.Presence of lithium iodide is important and excess of chlorotrimethylsilane accelerates the reactions.The combination of organocopper compound, iodotrimethylsilane and dimethyl sulfide gave faster reactions and very high yields, particularly in dichloromethane, where the reaction mixtures gradually became homogeneous.
