- Aerobic Acyloxylation of Allylic C?H Bonds Initiated by a Pd0 Precatalyst with 4,5-Diazafluoren-9-one as an Ancillary Ligand
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Palladium-catalyzed allylic C?H oxidation has been widely studied, but most precedents use acetic acid as the coupling partner. In this study, a method compatible with diverse carboxylic acid partners has been developed. Use of a Pd0 precatalyst under aerobic reaction conditions leads to oxidation of Pd0 by O2 in the presence of the desired carboxylic acid to generate a PdII dicarboxylate that promotes acyloxylation of the allylic C?H bond. Good-to-excellent yields are obtained with a roughly 1:1 ratio of the alkene and carboxylic acid reagents. Optimized reaction conditions employ 4,5-diazafluoren-9-one (DAF) as a ligand, in combination with a quinone/iron phthalocyanine cocatalyst system to support aerobic catalytic turnover.
- Kozack, Caitlin V.,Sowin, Jennifer A.,Jaworski, Jonathan N.,Iosub, Andrei V.,Stahl, Shannon S.
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p. 3003 - 3007
(2019/06/17)
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- Visible Light-Mediated Synthesis of Enantiopure g-Cyclobutane Amino and 3-(Aminomethyl)-5-phenylpentanoic Acids
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A visible light-mediated [2+2] photocycloaddition of amide-linked dienes using [Ir(dtb-bpy)(dF(CF3)ppy)2]PF6 as triplet sensitizer was applied to generate a variety of N-tert-butyl, N-benzyl- and N-tert-butoxycarbonyl-protected 3-aza-bicyclo[3.2.0]heptan-2-ones in good yields and with good diastereoselectivity. Density functional theory calculations shed light on the conformational prerequisites for the [2+2] photocycloaddition. The bicyclic key structures could be readily transformed into g-cyclobutane amino acids. For the obtained racemic 3-phenyl-2-aminocyclobu-tane-1-carboxylic acid the resolution with chiral oxazolidin-2-one is demonstrated to allow access to both enantiomers. Alternatively, a chiral auxiliary approach led as well to the enantiomerically pure target compound. Finally, the synthesis of either enantiomer of 3-(aminomethyl)-5-phenylpentanoic acid, the racemate being described as an anticonvulsant is described.
- Kerres, Sabine,Plut, Eva,Malcherek, Simon,Rehbein, Julia,Reiser, Oliver
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supporting information
p. 1400 - 1407
(2019/10/28)
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- Visible Light-Mediated Synthesis of Enantiopure γ-Cyclobutane Amino and 3-(Aminomethyl)-5-phenylpentanoic Acids
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A visible light-mediated [2+2] photocycloaddition of amide-linked dienes using [Ir(dtb-bpy)(dF(CF3)ppy)2]PF6 as triplet sensitizer was applied to generate a variety of N-tert-butyl, N-benzyl- and N-tert-butoxycarbonyl-protected 3-azabicyclo[3.2.0]heptan-2-ones in good yields and with good diastereoselectivity. Density functional theory calculations shed light on the conformational prerequisites for the [2+2] photocycloaddition. The bicyclic key structures could be readily transformed into γ-cyclobutane amino acids. For the obtained racemic 3-phenyl-2-aminocyclobutane-1-carboxylic acid the resolution with chiral oxazolidin-2-one is demonstrated to allow access to both enantiomers. Alternatively, a chiral auxiliary approach led as well to the enantiomerically pure target compound. Finally, the synthesis of either enantiomer of 3-(aminomethyl)-5-phenylpentanoic acid, the racemate being described as an anticonvulsant, is described.
- Kerres, Sabine,Plut, Eva,Malcherek, Simon,Rehbein, Julia,Reiser, Oliver
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- Preparation method of cinnamyl cinnamate
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The invention relates to a preparation method of cinnamyl cinnamate. In an oil bath, methyl cinanmate, cinnamyl alcohol and potassium carbonate are mixed and heated under stirring, and low boiling substances are distilled off while reacting, heating is stopped to cool, water and ethyl acetate are added for washing until the water phase is neutral, and the oil phase is subjected to reduced pressuredistillation after being heated to recover ethyl acetate so as to obtain cinnamyl cinnamate crude products, and the cinnamyl cinnamate crude products are recrystallized from ethanol to obtain white solid cinnamyl cinnamate. The preparation method has the advantages of simple process, short cycle, high yield, simple post-treatment, green environmental protection and the like. The cinnamyl cinnamate prepared according to the method has the advantages of pure aroma, good color, high purity and the like.
- -
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Paragraph 0054-0061; 0064; 0072; 0080
(2018/04/26)
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- Rethinking the Claisen–Tishchenko Reaction
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Pincer-type complexes [OsH2(CO){PyCH2NHCH2CH2NHPtBu2}] and [OsH2(CO){HN(CH2CH2PiPr2)2}] catalyze the disproportionation reaction of aldehydes via an outer-sphere bifunctional mechanism achieving turnover frequencies up to 14 000 h?1. The N?H group of the catalysts is a key player in this process, elucidated with the help of DFT calculations.
- Morris, Stacey A.,Gusev, Dmitry G.
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supporting information
p. 6228 - 6231
(2017/05/19)
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- NHC-catalyzed one-pot oxidation and oxidative esterification of allylic alcohols using TEMPO: The effect of alcohol additives
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A combination of N-heterocyclic carbene (NHC) catalysts and 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) was proposed for the synthesis of allylic esters from allylic alcohols. The yield of one-pot conversion of allylic alcohols to esters increased when hexafluoroisopropanol (HFIP) was used. The effect of HFIP in this tandem reaction was investigated by monitoring the reaction using gas chromatographic analysis. Control experiments using oxoammonium showed that the oxidative esterification occurred via a single-electron transfer mechanism.
- Kang, Ye-Won,Jang, Hye-Young
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p. 44486 - 44490
(2015/01/09)
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- Modified Yamaguchi reagent: Convenient and efficient esterification
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A convenient and efficient esterification method that used a modified Yamaguchi reagent (2,4,6-trichlorobenzoyl chloride-4-dimethylaminopyridine) and avoided use not only of intractable acid chloride but also of acid anhydrides was proposed. The reaction mechanism was described by Fourier transform infrared spectroscopy and supported by a density functional theory calculation.
- Okuno, Yoshinori,Isomura, Shigeki,Nishibayashi, Akihiro,Hosoi, Aiko,Fukuyama, Kei,Ohba, Masashi,Takeda, Kazuyoshi
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supporting information
p. 2854 - 2860
(2014/10/15)
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- N-heterocyclic carbene catalysed oxidative coupling of aldehydes with alcohols/thiols and one-pot oxidation/esterification of allylic alcohols
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A versatile carbene-catalysed oxidation protocol involving N-heterocyclic carbene catalysts and 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) is described for the synthesis of esters, cinnamic acids, and thioesters. A wide range of esters, thioesters, and cinnamic acids were obtained by metal-free coupling of aldehydes with aliphatic, allylic and aromatic alcohols, benzyl mercaptan, and water. In addition to the oxidative coupling of aldehydes with nucleophiles, dehydrogenation of saturated aldehydes and oxidation of allylic alcohols were found under our oxidative coupling conditions. Unlike other TEMPO-mediated oxidative esterification reactions, this reaction does not proceed through a TEMPO ester intermediate to form esters and thioesters. N-Heterocyclic carbene complexes catalyse various oxidative coupling reactions in the presence of TEMPO. A variety of α,β-unsaturated and saturated esters, and aromatic esters and thioesters were synthesised. Copyright
- Ji, Miran,Wang, Xi,Lim, Yu Na,Kang, Ye-Won,Jang, Hye-Young
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supporting information
p. 7881 - 7885
(2014/01/06)
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- Palladium-catalyzed oxidative diarylating carbocyclization of enynes
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A mild and efficient palladium-catalyzed oxidative diarylating carbocyclization of enynes is described. The reaction tolerates a range of functionalized arylboronic acids to give diarylated products in good yields. Control experiments suggest that the reaction starts with an arylpalladation of the alkyne, followed by carbocyclization, transmetalation, and reductive elimination to afford the diarylated product.
- Jiang, Min,Jiang, Tuo,B?ckvall, Jan-E.
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experimental part
p. 3538 - 3541
(2012/08/28)
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- Nucleophilic carbene-catalyzed redox-esterification reaction of α-halo-α,β-unsaturated aldehyde
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A nucleophilic carbene catalyzed redox esterification between α-halo-α,β-unsaturated aldehydes and various alcohols has been developed. Interestingly, the reaction provided α,β-unsaturated esters instead of the saturated α-halo substituted esters as the only product in good to high yield with excellent trans-selectivity, presumably via the umpolung-halo-elimination pathway.
- Wang, Xiang-Bo,Zou, Xiao-Lei,Du, Guang-Fen,Liu, Zhi-Yong,Dai, Bin
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experimental part
p. 6498 - 6503
(2012/08/27)
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- NHC-catalyzed C-O or C-N bond formation: Efficient approaches to α,β-unsaturated esters and amides
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Simple and efficient NHC-catalyzed transformations of bromoenal or α,β-dibromoenal into α,β-unsaturated esters or amides with high stereoselectivity through C-O or C-N bond formation have been demonstrated. The NHC-catalyzed processes occur under mild con
- Zhang, Bo,Feng, Peng,Cui, Yuxin,Jiao, Ning
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supporting information; experimental part
p. 7280 - 7282
(2012/07/28)
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- Pd(II)-catalyzed direct olefination of arenes with allylic esters and ethers
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A convenient Pd(II)-catalyzed direct olefination of unactivated arenes with allylic esters and ethers via C-H activation was demonstrated. Under the typical conditions, various aryl-substituted allylic esters and ethers can be prepared. Georg Thieme Verlag Stuttgart - New York.
- Shang, Xiaojie,Xiong, Yun,Zhang, Yuexia,Zhang, Lei,Liu, Zhongquan
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supporting information; experimental part
p. 259 - 262
(2012/03/08)
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- N-heterocyclic carbene-mediated oxidative esterification of aldehydes: Ester formation and mechanistic studies
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An unexpected N-heterocyclic carbene-catalyzed esterification of α,β-unsaturated aldehydes including aromatic aldehydes with reactive cinnamyl bromides in the presence of air oxygen or MnO2 as an oxidant is described. In the presence of oxygen, halogenated and electron-deficient aldehydes react smoothly to furnish esters in good yields. Great efforts have been made on mechanistic studies to deduce a plausible mechanism, based on the experimental results and isotopic labeling experiment.
- Maji, Biswajit,Vedachalan, Seenuvasan,Ge, Xin,Cai, Shuting,Liu, Xue-Wei
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experimental part
p. 3016 - 3023
(2011/06/20)
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- Allylation of 1-phenyl-1-propyne with N- and O-pronucleophiles using polymer supported triphenylphosphine palladium complex as a heterogeneous and recyclable catalyst
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Simple methodology for the allylation of various N- and O-pronucleophiles with 1-phenyl-1-propyne as an allylating agent, using PS-TPP-Pd (polymer supported triphenylphosphine palladium) as a highly active heterogeneous recyclable catalyst has been developed. The protocol is applicable for a wide variety of hindered and functionalized aromatic amines, alcohols, and carboxylic acids. The catalyst exhibited remarkable catalytic activity for five consecutive recycles.
- Wagh, Yogesh S.,Sawant, Dinesh N.,Dhake, Kishor P.,Deshmukh, Krishna M.,Bhanage, Bhalchandra M.
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experimental part
p. 5676 - 5679
(2011/11/06)
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- Pd(OAc)2/dppf as an efficient and highly active catalyst for the allylation of amines, alcohols and carboxylic acids with 1-phenyl-1-propyne
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Pd(OAc)2/1,1′-bis(diphenylphosphino)ferrocene as an efficient, highly active catalyst for the allylation of amines, alcohols and carboxylic acids with 1-phenyl-1-propyne has been developed. The effect of various reaction parameters, such as ligand, time, solvent, temperature, metal: ligand ratio and catalyst concentration on yields of the product were investigated. The optimized procedure works well under mild operating conditions and permits rapid generation of a library for various allylated products.
- Wagh, Yogesh S.,Sawant, Dinesh N.,Tambade, Pawan J.,Dhake, Kishor P.,Bhanage, Bhalchandra M.
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experimental part
p. 2414 - 2421
(2011/04/26)
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- Nucleophilic iron catalysis in transesterifications: Scope and limitations
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Figure presented The ester bond is one of the most common structural motifs found in nature. Apart from the condensation between an acid and an alcohol, transesterifications represent another mechanistic alternative for the preparation of this compound class. The present paper summarizes our most recent investigations in this field, using nucleophilic iron complexes as catalysts for transesterifications under neutral conditions. This new type of metal catalyst complements the existing methodologies, which rely on Lewis acidic metal complexes. Investigations on scope and limitations, stereochemical course, and chemoselectivities will be presented.
- Magens, Silja,Plietker, Bernd
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supporting information; experimental part
p. 3715 - 3721
(2010/08/07)
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- Recyclable gold nanoparticle catalyst for the aerobic alcohol oxidation and C-C bond forming reaction between primary alcohols and ketones under ambient conditions
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A recyclable gold catalyst is synthesized from readily available reagents by immobilizing gold nanoparticles in aluminum oxyhydroxide support through a simple sol-gel method. The catalyst showed the high activity even at room temperature in the aerobic oxidation of various alcohols and in the coupling reaction between primary alcohols and ketones.
- Kim, Sungjin,Bae, Sang Won,Lee, Jae Sung,Park, Jaiwook
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experimental part
p. 1461 - 1466
(2009/04/11)
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- Cl3CCONH2/PPh3: A versatile reagent for synthesis of esters
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Cl3CCONH2/PPh3 was a versatile reagent to convert carboxylic acids into their corresponding acid chlorides. This intermediate was clearly confirmed by spectroscopic methods (IR, 1H, 13C NMR). This one-pot reaction of in situ acid chloride generated with various alcohols successfully furnished the corresponding esters in moderate to excellent yields. Copyright ? Taylor & Francis Group, LLC.
- Chantarasriwong, Oraphin,Jang, Doo Ok,Chavasiri, Warinthorn
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scheme or table
p. 2845 - 2856
(2009/04/11)
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- An efficient chemoselective strategy for the preparation of (E)-cinnamic esters from cinnamaldehydes using heterogeneous catalyst and DDQ
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An efficient chemoselective protocol is developed for the synthesis of (E)-cinnamic esters from substituted cinnamaldehydes or cinnamyl alcohols using a combination of DDQ and heterogeneous catalyst under microwave irradiation. The method showed remarkable selectivity for cinnamaldehydes over aliphatic and aromatic aldehydes, which is a novel finding. The results demonstrate that the developed protocol can be a useful synthetic tool for chemoselective esterification in total synthesis of complex organic compounds.
- Sinha, Arun K.,Sharma, Anuj,Swaroop, Anand,Kumar, Vinod
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p. 1000 - 1007
(2007/10/03)
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- A facile microwave assisted synthesis and antimicrobial activities of naturally occurring (E)-cinnamyl (E)-cinnamates and (E)-aryl cinnamates
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Benzaldehydes 1a-e on reaction with phosphorane 3 and aldehydes 2a-e with phosphorane 4 under microwave irradiation provide the (E)-cinnamyl (E)-cinnamates 5a-e and (E)-aryl cinnamates 6a-e respectively in high yield. Cinnamates 5a-e and 6a-e exhibit antibacterial and antifungal activity.
- Mahajan, Rajesh P,Patil, Ulhas K,Patil, Shamkant L
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p. 1459 - 1465
(2008/09/18)
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- A fast and simple method for the acylation of alcohols with acid chlorides promoted by metallic samarium
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Acylation of primary, secondary, allyl and benzyl alcohols with acid chlorides promoted by samarium metal under neutral condition gave carboxylic acid esters in good to excellent yields. Acylation of a tertiary alcohol did not occur under the same reaction conditions.
- Jia, Xue-Shun,Wang, Hai-Long,Huang, Qing,Kong, Ling-Long,Zhang, Wei-He
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p. 135 - 138
(2007/10/03)
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- Synthesis and biological evaluation of a natural ester sintenin and its synthetic analogues
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Synthesis of 3-(3,4-dimethoxyphenyl)propyl-3-(3,4-dimethoxyphenyl) propanoate (18), a cytotoxic natural ester, was carried out by a convenient synthetic path with a total yield of 49%. Sixteen of its analogues (19-34) were also prepared. Seventeen unsaturated derivatives of 18, compounds 1-17, were also synthesized to examine the structure-activity relationship of this type of ester. All of the synthetic compounds were passed through the cytotoxicity screenings on human tumor cell lines, such as PC-3, Hela, A549, BEL7404, CNE, and KB. Some of the esters exhibited moderate inhibitory effects on these tumor cell lines. The phenolic derivatives exhibited the highest cytotoxicity among these derivatives, while the unsaturated esters were more cytotoxic than the saturated analogues. Some of the compounds also exhibited inhibition on α-glucosidase.
- Hu, Li Hong,Zou, Hong Bin,Gong, Jing Xu,Li, Hai Bo,Yang, Lei Xiang,Cheng, Wei,Zhou, Chang Xin,Bai, Hua,Gueritte, Francoise,Zhao, Yu
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p. 342 - 348
(2007/10/03)
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- Iridium-catalyzed oxidative dimerization of primary alcohols to esters using 2-butanone as an oxidant
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Oxidative dimerization of primary alcohols with 2-butanone in the presence of an amino alcohol-based Ir bifunctional catalyst was accomplished for the first time. The reaction proceeds with 1-2 mol% of the catalyst and 0.3 mol equivalents of K2CO3 in 2-butanone at room temperature to give the corresponding dimeric esters in 30-93% yield. Georg Thieme Verlag Stuttgart.
- Suzuki, Takeyuki,Matsuo, Tomohito,Watanabe, Kazuhiro,Katoh, Tadashi
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p. 1453 - 1455
(2007/10/03)
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- Iron perchlorate on silica gel as multi-purpose reagent for catalysis of closure and rupture of carbon-oxygen bond in epoxides, alcohols, and esters
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Aliphatic alcohols and water in the presence of catalytic amounts of Fe3+ ion introduced as iron(III) perchlorate on silica gel carrier perform efficient regiospecific opening of an epoxy ring. Carbon acids esterification with various type alcohols was carried out using the system Fe(ClO4)3-silica gel in dichloromethane under conditions excluding solvolysis. Acetylation and formylation of alcohols was performed by efficient transesterification with ethyl acetate and ethyl formate.
- Salechi,Khodaei,Ghareghani,Motlagh
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p. 794 - 796
(2007/10/03)
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- Fluoroalkyldistannoxane Catalysts for Transesterification in Fluorous Biphase Technology
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Novel, practical protocols of transesterification have been advanced with recourse to fluorous biphase technology. The fluoroalkyldistannoxane catalysts enable transesterification in FC-72 solvent to furnish 100% yields of the desired esters by use of reactants ester and alcohol in a 1:1 ratio. The catalysts also work in FC-72/organic solvent system as well as in toluene alone. A number of esters and alcohols bearing various functional groups are employable. The catalysts can be totally recovered and reused. More conveniently, the catalyst solution in FC-72 which is separated from the reaction mixture is directly used for the next reaction.
- Xiang, Jiannan,Orita, Akihiro,Otera, Junzo
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- A practical and green chemical process: Fluoroalkyldistannoxane-catalyzed biphasic transesterification
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There is no need for the recovery of the catalyst in the fluorous biphasic transesterification catalyzed by [{Cl(C6F13CH2CH2)2 SnOSn(C6F13CH2CH2) 2Cl}2] (1; see scheme), which results in quantitative conversions and yields. An FC-72 solution of the dimeric flouroalkyldistannoxane 1 can be recycled repeatedly without having to recover the neat catalyst.
- Xiang, Jiannan,Toyoshima, Shinji,Orita, Akihiro,Otera, Junzo
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p. 3670 - 3672
(2007/10/03)
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- Synthesis of naturally occurring cinnamyl cinnamates
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A convenient, high yield and general method is described for the synthesis of cinnamyl cinnamates (1a-f, 2a-c and 2e) from benzaldehydes (7a-f). The aldehydes (7a-f) on reaction with phosphorane (6) provide the (E,E)- cinnamyl cinnamates (1a-f) in high yields together with the (E,Z)- esters (2a-c and 2e) in low yields in the same reaction.
- Mali,Papalkar
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p. 433 - 435
(2007/10/03)
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- Highly chemoselective catalytic hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols using phosphine-stabilized copper(I) hydride complexes
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A base metal hydrogenation catalyst composed of the phenyldimethylphosphine-stabilized copper(I) hydride complex provides for the highly chemoselective hydrogenation of unsaturated ketones and aldehydes to unsaturated alcohols, including the regioselective 1,2-reduction of α,β- unsaturated ketones and aldehydes to allylic alcohols. The active catalyst can be derived in situ by phosphine exchange using commercial [(Ph3P)CuH]6 or from the reaction of copper(l) chloride, sodium tert-butoxide, and dimethylphenylphosphine under hydrogen. The catalyst derived from 1,1,1- tris(diphenylphosphinomethyl)ethane is mechanistically interesting but less synthetically useful. (C) 2000 Elsevier Science Ltd.
- Chen, Jian-Xin,Daeuble, John F.,Brestensky, Donna M.,Stryker, Jeffrey M.
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p. 2153 - 2166
(2007/10/03)
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- Trimethylamine-Borane a Useful Reagent in the One-Pot Preparation of Carboxylic Esters from Carboxylic Acids
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The carboxylic esters 2a-h (R1CO2CH2R1) and 4a-d (R1CO2CH2R2) are synthesized from alkyl or aryl carboxylic acids, a one-pot reaction involving in situ reduction followed by esterification, both steps are mediated by trimethylamine-borane.
- Trapani, Giuseppe,Reho, Antonia,Latrofa, Andrea,Liso, Gaetano
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p. 853 - 854
(2007/10/02)
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