- Odor-structure relationships using fluorine as a probe
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Eight ethers, nine esters and one ketone were submitted to a systematic structural variation by replacing a hydrogen atom in the vicinity of the oxofunction by fluorine and methyl. As long as steric factors dominate, a fluorine substituent alters the olfactory properties of the parent compound much less than a methyl substituent does. However, if it occupies a position adjacent to a carbonyl group, the halogen may more profoundly affect the odor perception, presumably as a consequence of conformational changes. (C) 2000 Elsevier Science Ltd.
- Michel, Dominique,Schlosser, Manfred
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Read Online
- Direct formation of esters and amides from carboxylic acids using diethyl chlorophosphate in pyridine
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An efficient method involving pyridine activation of the carboxylate-phosphate anhydride pathway is described resulting in a direct synthesis of esters from carboxylic acids and alcohols, as well as in the formation of useful amide and peptide derivatives. The reaction proceeds with retention of configuration with both chiral secondary alcohols and α-amino acid derivatives. Ester and amide products can be isolated directly in high yield due to the water soluble nature of the side products.
- McNulty, James,Krishnamoorthy, Venkatesan,Robertson, Al
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Read Online
- Synthesis method of p-hydroxyphenethyl alcohol
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The invention discloses a method for synthesizing p-hydroxyphenethyl alcohol from phenethyl alcohol as a raw material. The method comprises the steps as follows: firstly, phenethyl alcohol and acid anhydride are subjected to an esterification reaction to obtain phenethyl alcohol ester; then, phenethyl alcohol ester and acid anhydride are subjected to an electrophilic substitution reaction under the action of a catalyst and a catalyst promoter to obtain 4-acryl phenethyl alcohol ester; next, 4-acryl phenethyl alcohol ester and hydrogen peroxide are subjected to a Baeyer-Villiger oxidation reaction under the action of organic acid and an oxidation catalyst to obtain 4-acyloxy phenethyl alcohol ester; finally, the 4-acyloxy phenethyl alcohol ester is subjected to a hydrolysis reaction in alkaline water to obtain p-hydroxyphenethyl alcohol. The process for synthesizing p-hydroxyphenethyl alcohol has the advantages that raw materials are widely sourced, the yield is high, the process is concise, few three wastes are produced and industrialization is easy to realize.
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Paragraph 0051; 0052; 0053
(2019/09/17)
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- Lewis Acid Catalyzed Synthesis of α-Trifluoromethyl Esters and Lactones by Electrophilic Trifluoromethylation
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An electrophilic trifluoromethylation of ketene silyl acetals (KSAs) by hypervalent iodine reagents 1 and 2 has been developed. The reaction proceeds under very mild conditions in the presence of a catalytic amount of trimethylsilyl bis(trifluoromethanesulfonyl)imide (up to 2.5 mol %) as a Lewis acid providing a direct access to a variety of secondary, tertiary, and quaternary α-trifluoromethyl esters and lactones in high yield (up to 98%).
- Katayev, Dmitry,Matou?ek, Václav,Koller, Raffael,Togni, Antonio
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supporting information
p. 5898 - 5901
(2015/12/11)
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- Expanding ester biosynthesis in Escherichia coli
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To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l -1). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.
- Rodriguez, Gabriel M,Tashiro, Yohei,Atsumi, Shota
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p. 259 - 265
(2014/04/03)
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- The phosphate-carboxylate mixed-anhydride method: A mild, efficient process for ester and amide bond construction
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A highly efficient carboxylate-phosphate anhydride pathway is described for the direct, economical synthesis of esters and amides from carboxylic acids and alcohols or amines. The reaction proceeds with retention of configuration with both chiral secondary alcohols and α-amino acid derivatives allowing access to useful chiral auxiliaries, ligands, and organocatalysts. Ester and amide products can be isolated directly in high yield due to the water soluble nature of the side products.
- McNulty, James,Vemula, Ramesh,Krishnamoorthy, Venkatesan,Robertson, Al
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experimental part
p. 5415 - 5421
(2012/09/08)
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- Pentafluorophenylammonium triflate as a mild and new organocatalyst for acylation of alcohols, phenols, and amines under solvent-free condition
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A simple, inexpensive, environmentally friendly and efficient route for the acylation of a number of alcohols, phenols and amines using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures.
- Khaksar, Samad,Zakeri, Hasan
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p. 576 - 579,4
(2020/08/31)
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- Organocatalytic chemoselective monoacylation of 1,n-linear diols
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Matters of length: Exclusive or predominant monoacylation of 1,n-linear diols took place in the presence of 1 when the chain length of linear diols was equal to or shorter than five carbon atoms. The chemoselectivity of acylation between 1,5-pentanediol (n=5) and 1,6-hexanediol (n=6) was 5.2, and that between 1,5-pentanediol and its monoacylate was 113. Copyright
- Yoshida, Keisuke,Furuta, Takumi,Kawabata, Takeo
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supporting information; experimental part
p. 4888 - 4892
(2011/06/22)
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- Transesterification catalyzed by iron(III) β-diketonate species
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A practical and clean protocol for transesterification catalyzed by a 5 mol % cheap, non-toxic and moisture stable Fe(acac)3 or other iron(III) β-diketonate species in solvent, such as heptane under azeotropic condition is developed. A remarkable rate enhancement was observed upon the addition of 5 mol % of an inorganic base, such as Na2CO3, which suggests that faster formation of a dimeric μ-alkoxy-bridged iron(III) species under alkaline conditions facilitates catalytic turnover. This system provides smooth transesterification over a wide range of structurally diverse esters and alcohols without disturbing functional groups. In addition, the use of iron β-diketonate complexes as catalysts is more environmentally friendly, safer, and economical than other transition-metal catalysts. Preliminary mechanistic studies indicate that the active catalyst is likely a dimeric μ-alkoxy-bridged iron(III) species, as determined by X-ray crystallography of [Fe(dbm)2(O-n-Bu)]2 derived from the alcoholysis of Fe(dbm)3 under alkaline conditions.
- Weng, Shiue-Shien,Ke, Chih-Shueh,Chen, Fong-Kuang,Lyu, You-Fu,Lin, Guan-Ying
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supporting information; experimental part
p. 1640 - 1648
(2011/04/17)
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- Indium-catalyzed synthesis of keto esters from cyclic 1,3-diketones and alcohols and application to the synthesis of seratrodast
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Esterification reactions from cyclic 1,3-diketones and alcohols are carried out in the presence of several Lewis acids. In particular, indium(III) triflate, In(OTf)3, iron(III) triflate, Fe-(OTf)3, copper(II) triflate, Cu(OTf)2, and silver(I) triflate, AgOTf, show high catalytic activities. These reactions proceed through the carbon-carbon bond cleavage by a retro-aldol reaction and were found to be highly regioselective even in the presence of other functional groups. This type of reaction can also be applied to the preparation of the keto esters during the synthesis of seratrodast, which is an antiasthmatic and eicosanoid antagonist.
- Kuninobu, Yoichiro,Kawata, Atsushi,Noborio, Taihei,Yamamoto, Syun-Ichi,Matsuki, Takashi,Takata, Kazumi,Takai, Kazuhiko
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experimental part
p. 941 - 945
(2010/07/07)
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- Air-stable titanocene bis(perfluorooctanesulfonate) as a new catalyst for acylation of alcohols, phenols, thiols, and amines under solvent-free condition
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Air-stable titanocene bis(perfluorooctanesulfonate) [Cp2Ti(OSO2C8F17)2] that shows high Lewis acidity was prepared from Cp2TiCl2 and AgOSO2C8F17. The compound was characterized by different techniques, and examined as a catalyst for acylation reactions. It was found that using equimolar acetic anhydride as acetylating agent and under solvent-free condition, Cp2Ti(OSO2C8F17)2 exhibits high activity and selectivity in the acetylation of various alcohols, phenols, thiols, and amines. Also, good catalytic efficiency is observed in the acylation of 2-phenylethanol across various acylating reagents. The catalyst can be reused without loss of activity in a test of ten cycles. The Cp2Ti(OSO2C8F17)2 catalyst affords a simple, efficient and general method for the acylation of alcohols, phenols, thiols, and amines.
- Qiu, Renhua,Zhang, Guoping,Ren, Xiaofang,Xu, Xinhua,Yang, Ronghua,Luo, Shenglian,Yin, Shuangfeng
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experimental part
p. 1182 - 1188
(2010/06/13)
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- Synthesis of aromatic alcohols and their alkanoic acid esters
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The reaction of benzene with ethylene and propylene oxides in a helium atmosphere with aluminum chloride as a catalyst and the esterification of the resulting alcohols with saturated monocarboxylic acids in the presence of the heterogeneous catalyst KU-2-8 were studied. Pleiades Publishing, Inc., 2006.
- Mamedov
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p. 408 - 410
(2008/02/03)
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- Nucleophilic acyl substitutions of anhydrides with protic nucleophiles catalyzed by amphoteric, oxomolybdenum species
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(Chemical Equation Presented) Among six different group VIb oxometallic species examined, dioxomolybdenum dichloride and oxomolybdenum tetrachloride were the most efficient catalysts to facilitate nucleophilic acyl substitution (NAS) of anhydrides with a myriad array of alcohols, amines, and thiols in high yields and high chemoselectivity. In contrast to the well-recognized redox chemical behaviors associated with oxomolybdenum(VI) species, the catalytic NAS was unprecedented and tolerates virtually all kinds of functional groups. By using benzoic anhydride as a mediator for in situ generation of an incipient mixed anhydride-MoO2Cl2 adduct with a given functional alkanoic acid, one can achieve oleate, dipeptide, diphenylmethyl, N-Fmoc-α-amino, pyruvic, and tert-butylthio ester, N-tert-butylamide, and trityl methacrylate syntheses with appropriate protic nucleophiles. The amphoteric character of the Mo=O unit in oxomolybdenum chlorides was found to be responsible for the catalytic NAS profile as supported by a control NAS reaction of using an authentic adduct-MoOCl2(O2-CBu t)2 between pivalic anhydride and MoO2Cl 2 as the catalyst.
- Chen, Chien-Tien,Kuo, Jen-Huang,Pawar, Vijay D.,Munot, Yogesh S.,Weng, Shieu-Shien,Ku, Cheng-Hsiu,Liu, Cheng-Yuan
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p. 1188 - 1197
(2007/10/03)
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- Catalytic nucleophilic acyl substitution of anhydrides by amphoteric vanadyl triflate
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Figure presented Among four vanadyl species examined, vanadyl triflate was the most efficient catalyst to facilitate nucleophilic acyl substitution of anhydrides with a myriad array of alcohols, amines, and thiols in high yields and high chemoselectivity. By using mixed-anhydride technique, one can achieve oleate and peptide syntheses. In marked contrast to common metal Inflates, the amphoteric character of the V=O unit in vanadyl species was proven to be responsible for the catalytic profile in this process.
- Chen, Chien-Tien,Chang, I-Hsin,Lin, Jin-Sheng,Liu, Chin-Jing,Chou, Y-Chen,Kuo, Jen-Huang,Li, Chun-Hsin,Barhate,Hon, Sang-Wen,Li, Tai-Wei,Chao, Shi-Deh,Liu, Chia-Cheng,Li, Ying-Chieh
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p. 3729 - 3732
(2007/10/03)
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- 2-Chloro-1,3-dimethylimidazolinium chloride. 1. A powerful dehydrating equivalent to DCC
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2-Chloro-1,3-dimethylimidazolinium chloride (DMC) (3) can act as a powerful dehydrating agent, replacing DCC (1) under nearly neutral conditions. Its application to acylation and dehydration is described.
- Isobe, Toshio,Ishikawa, Tsutomu
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p. 6984 - 6988
(2007/10/03)
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- Organic Reducing Agents. Reduction of Electron Deficient Bromides by 1,2,2,6,6-Pentamethylpiperidine (PMP)/Mercaptoethanol
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1,2,2,6,6-pentamethylpiperidine (PMP) is shown to be an effective reducing agent for the radical chain conversion of primary bromoesters in these reactions to the corresponding esters.The problem of inefficient reduction of tertiary bromoesters in these reactions has been overcome by the addition of an alkyl thiol which mediates the hydrogen atom transfer between the two hindered alkyl centers.
- Amoli, Maryam,Workentin, Mark S.,Wayner, Danial D. M.
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p. 3997 - 4000
(2007/10/02)
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- Organic Reducing Agents: Some Radical Chain Reactions of Ketyl and 1,3-Dioxolanyl Radicals with Activated Bromides
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The radical chain reduction of primary and secondary α-bromo esters by 2-propanol and 2-methyldioxolane has been shown to be a kinetically viable process with average chain lengths of >10 at temperatures between 30 and 60 deg C.For electron-deficient bromides, these simple organic reagents may effectively replace the more commonly used (and more expensive) organosilicon or tin hydrides.Some mechanistic insights have been obtained from a combination of kinetic and thermodynamic measurements.The rate constants for the reaction of the 2-hydroxy-2-propyl and the 2-methyl-1,3-dioxolan-2-yl radicals with a primary bromo ester have been estimated to be 8E3 M-1s-1 and 6E3 M-1s-1, respectively, at 30 deg C in acetonitrile.The electrochemical oxidation potentials of a number of electron-rich radicals derived from hydrogen atom abstraction from alcohols and dioxolanes, determined using photomodulation voltammetry, provide an assessment of the thermochemistry of the putative outer sphere electron-transfer reaction between the radical and the α-bromo ester (the value for 1,3-dioxolane has been redetermined and corrects an erroneous value previously published).From these data, it is shown that the order of reactivity of the organic reducing agents follows the same trend as the oxidation potentials of the corresponding radicals.Rate constants for the outer sphere electron-transfer reduction of the bromo esters by electrochemically generated radical anions were used to establish a Marcus-type relationship between the rate constants and the standard potential of the reducing agent.Comparison of these rate constants with those for the reactions of the electron-rich radicals suggest that the reactions of the methanol- and ethanol-derived radicals do not proceed via outer sphere electron transfer as had been previously suggested but have significant bonding (i.e., atom transfer) character at the transition state.Electron transfer in the reactions of the 2-propanol-, and 2-methyl-1,3-dioxolane-derived radicals cannot be rulled out.Nevertheless, the order of reactivity of the organic reducing agents follows the same trend as the oxidation potentials of the corresponding radicals suggesting that these potentials can be used as a predictive tool for the design of new reagents.
- Fontana, Francesca,Kolt, Ralph J.,Huang, Youqin,Wayner, Danial D. M.
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p. 4671 - 4676
(2007/10/02)
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- N,N,N',N'-TETRAMETHYLCHLOROFORMAMIDINIUM CHLORIDE AS AN EFFICIENT CONDENSATION REAGENT FOR A NOVEL ESTERIFICATION APPLICABLE TO THE MACROLIDE SYNTHESIS
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N,N,N',N'-Tetramethylchloroformamidinium chloride, prepared easily from N,N,N',N'-tetramethylurea and oxalyl chloride, is found to be an efficient condensation reagent for an esterification of carboxylic acids with alcohols umder mild conditions in one-pot procedure, and the reagent is applied to the lactonization for macrolide synthesis from ω-hydroxycarboxylic acids.
- Fujisawa, Tamotsu,Mori, Toshiki,Fukumoto, Kazumasa,Sato, Toshio
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p. 1891 - 1894
(2007/10/02)
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- DIALKYL ACYLPHOSPHONATES: A NEW ACYLATING AGENT OF ALCOHOLS
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Diethyl benzoylphosphonate (1) underwent facile benzoylation of alcohols in the presence of DBU.Reactions of diols containing primary and secondary hydroxyl groups with 1 gave predominantly monobenzoates in which primary hydroxyl groups were highly selectively benzoylated.Related acylations were also described.
- Sekine, Mitsuo,Kume, Akiko,Hata, Tsujiaki
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p. 3617 - 3620
(2007/10/02)
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