- Iodobenzene Dichloride in the Esterification and Amidation of Carboxylic Acids: In-Situ Synthesis of Ph3PCl2
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A novel, in-situ synthesis of dichlorotriphenylphosphorane (Ph3PCl2) is accomplished upon combining PPh3and the easily prepared hypervalent iodine reagent iodobenzene dichloride (PhICl2). The phosphorane is selectively generated in the presence of carboxylic acid or alcohol residues to rapidly produce acyl chlorides and alkyl chlorides in high yields. Addition of EtOH, PhOH, BnOH, Et2NH or CH2N2results in the direct synthesis of esters, amides and diazo ketones from carboxylic acids.
- Carle, Myriam S.,Shimokura, Grace K.,Murphy, Graham K.
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supporting information
p. 3930 - 3933
(2016/08/24)
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- Generation and trapping of ketenes in flow
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Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95% conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (Ea = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.
- Henry, Cyril,Bolien, David,Ibanescu, Bogdan,Bloodworth, Sally,Harrowven, David C.,Zhang, Xunli,Craven, Andy,Sneddon, Helen F.,Whitby, Richard J.
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p. 1491 - 1499
(2015/03/04)
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- Organocatalytic oxidation of aldehydes to mixed anhydrides
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TEMPO catalyzes the direct oxidation of aldehydes to mixed anhydrides in the presence of a carboxylic acid. The anhydrides can be converted in situ to esters, secondary, tertiary or Weinreb amides in high yield. Oxidation of the aldehyde directly to 2-propyl esters is also possible using only catalytic amounts of acid. The oxidation reactions are rapid and take place under mild conditions.
- Toledo, Hila,Pisarevsky, Evgeni,Abramovich, Adi,Szpilman, Alex M.
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p. 4367 - 4369
(2013/06/05)
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- Oxidation of primary aliphatic and aromatic aldehydes with difluoro(aryl)-λ3-bromane
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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.
- Ochiai, Masahito,Yoshimura, Akira,Hoque, Md. Mahbubul,Okubo, Takuji,Saito, Motomichi,Miyamoto, Kazunori
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supporting information; experimental part
p. 5568 - 5571
(2011/12/03)
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- Synthesis, antimicrobial evaluation, QSAR and in silico ADMET studies of decanoic acid derivatives
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Various derivatives of decanoic acid (CD) have been synthesized and evaluated against Gram positive B. subtilis, S. aureus and Gram negative E. coli bacteria as well as against fungi C. albicans and A. niger. Quantitative structure activity relationship (QSAR) models for antimicrobial activities were developed using multiple linear regression and cross validated by leave one out (LOO) approach. QSAR studies indicated that activity against Gram positive bacteria was governed by lipophilicity of the compounds while topological steric nature of the molecule was deciding factor for antifungal activity. Further, in silico ADMET studies showed that compounds CD12, 19, 20 and 23 could be explored further for other activities.
- Kumar, Ashwani,Singh, Surender,Jain, Sandeep,Kumar, Parvin
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experimental part
p. 191 - 204
(2011/10/09)
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- Zwitterionic salts as mild organocatalysts for transesterification
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(Chemical Equation Presented) The exothermic reaction of 3,5-bis(trifluoromethyl)phenyl or 4-nitrophenyl isothiocyanate with 4-pyrrolidinopyridine (PPY) gave the corresponding arylaminothiocarbonylpyridinium salts in quantitative yields. These novel zwitterionic salts were effective as organocatalysts for the transesterification reaction of an equimolar mixture of methyl carboxylates and alcohols in hydrocarbons such as heptane and octane under azeotropic reflux conditions with the removal of methanol. In sharp contrast, PPY was inert as a catalyst under the same reaction conditions.
- Ishihara, Kazuaki,Niwa, Masatoshi,Kosugi, Yuji
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supporting information; experimental part
p. 2187 - 2190
(2009/05/27)
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- Process for the preparation of carboxylic benzyl esters
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Carboxylic benzyl esters can be prepared by reacting benzyl chloride with carboxylic acids in the presence of one or more quaternary ammonium carboxylates as catalyst.
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- A Simple and Efficient Esterification Method
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A convenient and practical esterification was realized and this reaction proceeded without a dehydrating reagent or water removal equipment. The synthesis of esters by reaction of carboxylic acids with various alcohols such as methyl, ethyl, isopropyl, isobutyl, allyl, benzyl, propargyl and decanyl alcohols were achieved with a catalytic amount of CBr4 under refluxing reaction condition.
- Ming-Yi, Chen,Lee, Adam Shih-Yuan
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p. 103 - 108
(2007/10/03)
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