- An efficient method for the preparation of: Tert -butyl esters from benzyl cyanide and tert -butyl hydroperoxide under the metal free condition
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A novel protocol to synthesize tert-butyl esters from benzyl cyanides and tert-butyl hydroperoxide has been successfully achieved. In the presence of tert-butyl hydroperoxide, Csp3-H bond oxidation, C-CN bond cleavage and C-O bond formation proceeded smoothly in one pot under the metal-free condition.
- Chen, Xiuling,Li, Yan,Wu, Minghu,Guo, Haibing,Jiang, Longqiang,Wang, Jian,Sun, Shaofa
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p. 102023 - 102027
(2016)
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Read Online
- 'New' catalysts for the ester-interchange reaction: The role of alkali-metal alkoxide clusters in achieving unprecedented reaction rates
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The catalytic effect of alkali-metal tert-butoxide clusters on the rate of ester interchange for several pairs of esters has been determined in nonpolar and weakly polar solvents. Reactivities increase in the order (Li+ + + + +) with the fastest rates reaching 107 catalytic turnovers per hour (TO/h). Ester interchange rates were sensitive to the size of both the transferring OR groups and the ester substituent. Phenyl esters did not exchange with aliphatic esters due to nonstatistical breakdown patterns in the tetrahedral intermediate. A first-order equilibration analysis on the interchange between tert-butyl acetate (tBuAc) and methyl benzoate (MeBz) (5 mol % NaOtBu) indicated enhanced reaction rates as the reaction proceeded. Isolation and quenching (DCl/D2O) of precipitated catalyst points to a mechanism whereby sequential methoxy incorporation into the catalyst cluster increases activity, but eventually precipitates out of solution as a 3:1 OMe:OtBu cluster. The rate law was determined to be k(obs)[MeBz]1[tBuAc]0[NaOtBu](x), where x = 1.2(1), 1.4(1), and 0.85(1) in hexane, ether, and THF, respectively, under conditions where tetrameric catalyst aggregates are expected. Reaction rates were generally observed to be higher in nonpolar solvents (hexane > toluene, ether > THF). Eyring analysis over a 40°C range yielded ΔH(≠) = 10.0(1) kcal mol-1 and ΔS(≠) = -32(3) eu. A Hammett (σ) plot generated with para-substituted methyl benzoates gave ρ +2.35 (R 0.996). These results are interpreted in terms of a catalytic cycle composed of two coupled transesterification reactions with a turnover-limiting addition of a tert-butoxy-containing cluster (tetramer) to methyl benzoate. Catalyst relative reactivities (Cs+ > Rb+ > K+ > Na+ > Li+) are interpreted in terms of competitive electrostatic interactions between the alkali-metal and ground-state and transition-state anions. This analysis predicts the observed linear dependence between log(k(obs)) and l/r(ionic).
- Stanton, Matthew G.
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Read Online
- A new reagent for the convenient synthesis of t-butyl esters from t-butanol
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An alumina-supported reagent has been prepared to synthesize the t-butyl esters from t-butanol. The method requires less time, mild conditions, and involves simplified work-up. Yield of the products is also high.
- Karmakar,Das
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Read Online
- Transition-metal-free alkoxycarbonylation of aryl halides
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Transitions: The title reaction has been developed for the synthesis of a variety of tert-butyl benzoates by employing 1,10-phenanthroline as an additive. Various functional groups were tolerated and heteroaryl iodides were also suitable substrates. Preli
- Zhang, Hua,Shi, Renyi,Ding, Anxing,Lu, Lijun,Chen, Borui,Lei, Aiwen
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Read Online
- An efficient protocol for the acylation of t-butanol in the presence of samarium diiodide
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Samarium diiodide (SmI2) promotes the rapid acylation of t-butanol with a variety of acid chlorides under neutral conditions to afford cleanly the corresponding t-butyl esters in excellent yields.
- Jia, Xueshun,Zhu, Li,Li, Qing,Li, Jian,Li, Dafeng,Li, Shaoyu
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Read Online
- Silver/manganese dioxide nanorod catalyzed hydrogen-borrowing reactions and tert-butyl ester synthesis
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Silver/manganese dioxide (Ag@MnO2) nanorods are synthesized and characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. It was discovered that Ag@MnO2 nanorods can realize hydrogen-borrowing reactions in high yields and are also effective for the synthesis of tert-butyl esters from aryl cyanides and tert-butyl hydroperoxide in a short period of time. Mechanistic experiments revealed that this catalytic system acts as a Lewis acid in hydrogen-borrowing reactions, while the synthesis of tert-butyl esters occurs through a radical pathway. This is the first report on the excellent catalytic activity of Ag@MnO2 nanorods as a catalyst.
- Luo, Huanhuan,Yang, Yike,Yang, Bobin,Xu, Zhaojun,Wang, Dawei
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p. 708 - 715
(2021/03/03)
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- A Zirconium Indazole Carboxylate Coordination Polymer as an Efficient Catalyst for Dehydrogenation-Cyclization and Oxidative Coupling Reactions
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Rational ligand design is crucial for achieving widespread applications of coordination polymers. The preparation, structural characterisation, and catalytic applications of zirconium (IV) coordination polymer (Zr-IDA), which was derived from 1-(carboxymethyl)-1H-indazole-5-carboxylic acid are reported. The Zr-IDA catalyst contains porous and highly crystalline particles with a quasi-spherical morphology around 100 nm in size, and Zr was coordinated with both O and N as shown by FT-IR and XPS measurements. Importantly, the Zr-IDA catalyst shows great activity, selectivity and stability in the oxidative coupling of benzyl cyanides with tert-butyl hydroperoxide to afford tert-butyl peresters, and the dehydrogenation cyclization of o-phenylenediamines with aromatic alcohols to afford 1,2-disubstituted benzimidazole derivatives. Mechanistic investigations were carried out to study these reactions and the developed catalytic system in more detail.
- Sang, Xinxin,Hu, Xinyu,Tao, Rong,Zhang, Yilin,Zhu, Haiyan,Wang, Dawei
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p. 123 - 129
(2020/02/21)
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- Novel nicotinoid structures for covalent modification of wood: An environmentally friendly way for its protection against insects
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Timber is constantly exposed to environmental influences under outdoor conditions which limits its lifetime and usability. In order to counteract the damaging processes caused by insects, we have developed a novel and more environmentally friendly method to protect wood materials via covalent modification by organic insecticides. Starting with an important class of synthetic insecticides which are derived from the natural insecticide nicotine, various new carboxylic acid derivatives of imidacloprid were made accessible. These activated neonicotinoids were utilized for the chemical modification of wood hydroxy groups. In contrast to conventional wood preservation methods in which biocides are only physically bound to the surface for a limited time, the covalent fixation of the preservative guarantees a permanent effect against wood pests, demonstrated in standardized biological tests. Additionally, the environmental interaction caused by non-bound neonicotinoids is significantly reduced, since both, a smaller application rate is required and leaching of the active ingredient is prevented. By minimizing the pest infestation, the lifetime of the material increases while preserving the natural appearance of the material.
- Acker, Sophie,Kaufmann, Dieter E.,Namyslo, Jan C.,Plarre, Rudy,S?ftje, Martin
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p. 15726 - 15733
(2020/05/13)
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- Construction of Esters through Sulfuryl Fluoride (SO 2 F 2) Mediated Dehydrative Coupling of Carboxylic Acids with Alcohols at Room Temperature
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A facile method for the construction of esters through dehydrative coupling of carboxylic acids with alcohols is developed. The reactions are mediated by sulfuryl fluoride (SO 2 F 2) at room temperature and proceed with high efficiency. The method has several advantages including broad substrate scope, mild conditions, excellent functional group compatibility and affords high yields, even on gram scale.
- Qin, Hua-Li,S Alharbi, Njud,Wang, Shi-Meng
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p. 3901 - 3907
(2019/10/11)
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- 3-(1-OXOISOINDOLIN-2-YL)PIPERIDINE-2,6-DIONE DERIVATIVES AND USES THEREOF
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The present disclosure provides a compound of Formula (I′): or a pharmaceutically acceptable salt, hydrate, solvate, prodrug, stereoisomer, or tautomer thereof, wherein R1, R2, Rx, X1, n, n1, and q are as defined herein, and methods of making and using same.
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Paragraph 0857; 0858
(2019/03/08)
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- Hydrosilane-Promoted Facile Deprotection of tert-Butyl Groups in Esters, Ethers, Carbonates, and Carbamates
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Combination of PdCl2 with 1,1,3,3-tetramethyldisiloxane in the presence of activated carbon was found to be an effective catalyst system for the cleavage reaction of C?O bond of O?t-Bu moieties. The present catalytic reaction offers a practical method for the deprotection of tert-butyl esters, tert-butyl ethers, O-Boc, and N-Boc derivatives under mild conditions. The addition of activated carbon in the reaction mixture was proved to be crucial for not only sustaining the catalytic activity but also trapping the palladium species after the reaction. (Figure presented.).
- Ikeda, Takuya,Zhang, Zhenzhong,Motoyama, Yukihiro
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supporting information
p. 673 - 677
(2019/01/04)
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- Picolinamide oligomers, preparation method and applications thereof
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The invention belongs to the technical field of membrane separation, and more specifically relates to picolinamide oligomers, a preparation method and applications thereof. The picolinamide oligomerscomprise the following characteristics: 1. the oligomers
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Paragraph 0047; 0051
(2018/08/28)
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- A fast and practical synthesis of tert-butyl esters from 2-tert-butoxypyridine using boron trifluoride·diethyl etherate under mild conditions
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A practical direct preparation of tert-butyl esters from 2-tert-butoxypyridine has been developed. This system features the use of boron trifluoride·diethyl etherate in toluene solvent to rapidly achieve the reaction at room temperature. Using this reaction protocol, a variety of tert-butyl esters were synthesized from several different carboxylic acids at high yields. This practical procedure provides a promising and effective approach to the protection of carboxylic acids with a tert-butyl group.
- La, Minh Thanh,Kim, Hee-Kwon
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p. 3748 - 3754
(2018/05/28)
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- Design, synthesis and structure?activity relationship studies of GPR40 agonists containing amide linker
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Free fatty acid receptor 1 (FFAR1/GPR40) attracted significant attention as a potential target for developing novel antidiabetic drugs because of its unique mechanism in glucose homeostasis. Several reports have expressed concerns about central nervous system (CNS) penetration of GPR40 agonists, which is possibly attributed to their high lipophilicity and low total polar surface area. Herein, we report our efforts to improve the physicochemical properties and pharmacokinetic profiles of LY2881835, a GPR40 agonist that had undergone Phase I clinical trial, through a series of structural optimizations. We identified an orally efficacious compound, 15k, which possessed increased plasma exposure, prolonged half-life and reduced CNS exposure and liver to plasma distribution ratio compared with LY2881835. 15k is a potentially valuable lead compound in the development of safe and efficacious GPR40-targeted drugs to treat type 2 diabetes mellitus.
- Chen, Tingting,Ning, Mengmeng,Ye, Yangliang,Wang, Kai,Leng, Ying,Shen, Jianhua
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p. 175 - 194
(2018/05/14)
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- Electrophilic Zinc Homoenolates: Synthesis of Cyclopropylamines from Cyclopropanols and Amines
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Metal homoenolates, produced via C-C bond cleavage of cyclopropanols, have been extensively investigated as nucleophiles for the synthesis of β-substituted carbonyl derivatives. Herein, we demonstrate that zinc homoenolates can react as carbonyl-electrophiles in the presence of nucleophilic amines to yield highly valuable trans-cyclopropylamines in good yields and high diastereoselectivities. GSK2879552, a lysine demethylase 1 inhibitor currently in clinical trials for the treatment of small cell lung carcinoma, was synthesized using this strategy.
- Mills, L. Reginald,Barrera Arbelaez, Luis Miguel,Rousseaux, Sophie A. L.
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supporting information
p. 11357 - 11360
(2017/08/30)
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- N-Methylanilines as Simple and Efficient Promoters for Radical-Type Cross-Coupling Reactions of Aryl Iodides
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Activation of the carbon–halogen bonds in aryl halides is a key step in transition-metal-free cross-coupling reactions. In this paper, a new and efficient radical initiation system for the activation of iodoarenes to produce aryl radicals was discovered, which employs the combination of N-methylanilines and tBuOK. This radical initiation system is robust and versatile, enabling various types of aryl-radical-related reactions.
- Yang, Huan,Zhang, Li,Jiao, Lei
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supporting information
p. 65 - 69
(2017/01/09)
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- Metal-free radical aromatic carbonylations mediated by weak bases
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We report a new method of metal-free alkoxycarbonylation. This reaction involves the generation of aryl radicals from arenediazonium salts by a very weak base (HCO2Na) under mild conditions. Subsequent radical trapping with carbon monoxide and alcohols gives alkyl benzoates. The conditions (metal-free, 1 equiv. base, MeCN, r.t., 3 h) tolerate various functional groups (I, Br, Cl, CF3, SF5, NO2, ester). Mechanistic studies indicate the operation of a radical aromatic substitution mechanism.
- Koziakov, Denis,Jacobi Von Wangelin, Axel
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supporting information
p. 6715 - 6719
(2017/08/22)
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- ALDOSTERONE SYNTHASE INHIBITORS
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The present invention relates to compounds of formula I: and pharmaceutically acceptable salts thereof, wherein X, R1, R2 and R3 are as defined herein. The invention also relates to pharmaceutical compositions comprising these compounds, methods of using these compounds in the treatment of various diseases and disorders, processes for preparing these compounds and intermediates useful in these processes.
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Page/Page column 34; 35
(2016/08/23)
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- Intramolecular rearrangement of α-azidoperoxides: An efficient synthesis of tert-butyl esters
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An unprecedented intramolecular rearrangement of α-azidoperoxides, promoted by simple organic base to provide tert-butyl esters, has been presented. Further, a one-pot methodology consisting of in situ generation of the α-azidoperoxides from corresponding aldehydes followed by base-promoted rearrangement to obtain the desired ester has also been executed. Relevant mechanistic studies, to provide the proof for intramolecular alkoxy transfer, are investigated.
- Pramanik, Suman,Reddy, Reddy Rajasekhar,Ghorai, Prasanta
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p. 1393 - 1396
(2015/03/30)
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- Metal-free carbonylations by photoredox catalysis
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The synthesis of benzoates from aryl electrophiles and carbon monoxide is a prime example of a transition-metalcatalyzed carbonylation reaction which is widely applied in research and industrial processes. Such reactions proceed in the presence of Pd or Ni catalysts, suitable ligands, and stoichiometric bases. We have developed an alternative procedure that is free of any metal, ligand, and base. The method involves a redox reaction driven by visible light and catalyzed by eosin Y which affords alkyl benzoates from arene diazonium salts, carbon monoxide, and alcohols under mild conditions. Tertiary esters can also be prepared in high yields. DFT calculations and radical trapping experiments support a catalytic photoredox pathway without the requirement for sacrificial redox partners.
- Majek, Michal,Von Wangelin, Axel Jacobi
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supporting information
p. 2270 - 2274
(2015/02/19)
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- Copper-catalyzed oxidative esterification of aldehydes with dialkyl peroxides: Efficient synthesis of esters of tertiary alcohols
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Copper-catalyzed oxidative esterification of aldehydes with dialkyl peroxides has been developed. This protocol affords a novel approach for the synthesis of carboxylic esters of tertiary alcohols under mild conditions. Depending on the catalyst system, a variety of tertiary esters were produced in good to excellent yields.
- Zhu, Yefeng,Wei, Yunyang
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p. 13668 - 13670
(2013/08/23)
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- Peroxisome proliferator-activated receptor agonists with phenethylphenylphthalimide skeleton derived from thalidomide-related liver X receptor antagonists: Relationship between absolute configuration and subtype selectivity
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Introduction of an alkylcarboxylic acid unit, which is a partial structure of endogenous peroxisome proliferator-activated receptor (PPAR) ligands, into a phenethylphenylphthalimide skeleton, which possesses liver X receptor (LXR) antagonistic activity, afforded novel PPAR ligands. The results of structure-activity relationship analysis and docking studies led us to the potent PPAR agonists 13c-e. The absolute configuration of 13c-e affects the PPAR subtype selectivity.
- Motoshima, Kazunori,Ishikawa, Minoru,Hashimoto, Yuichi,Sugita, Kazuyuki
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experimental part
p. 3156 - 3172
(2011/06/26)
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- One-pot esterification and Ritter reaction: Chemo- and regioselectivity from tert-butyl methyl ether
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tert-Butyl methyl ether (TBME) has been effectively used as a reagent for esterification of carboxylic acids. By varying amounts of sulfuric acid, a remarkable regioselectivity in esterification has been demonstrated. Additionally, under the present reaction conditions, one-pot esterification and Ritter reaction are achieved in almost quantitative yield.
- Dawar, Pankaj,Bhagavan Raju,Ramakrishna, Ramesha A.
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supporting information; experimental part
p. 4262 - 4265
(2011/08/21)
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- D2 ANTAGONISTS, METHODS OF SYNTHESIS AND METHODS OF USE
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Provided are D2 or D3 antagonist compounds and pharmaceutical compositions of formula I and pharmaceutically acceptable salts thereof, or isomers thereof, wherein R1, R2 and R3 are as defined herein. The invention further comprises methods for making the compounds of the invention and methods for the treatment of conditions mediated by the dopamine D2 or D3 receptor from the compounds of the invention.
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Page/Page column 122
(2012/01/06)
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- Dicarboxylic Acid Derivatives and their Use
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The present application relates to novel dicarboxylic acid derivatives, process for their preparation, their use for the treatment and/or prophylaxis of diseases, and their use for producing medicaments for the treatment and/or prophylaxis of diseases, es
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Page/Page column 20
(2010/03/02)
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- A flow microreactor system enables organolithium reactions without protecting alkoxycarbonyl groups
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A flow microreactor system consisting of micromixers and microtube reactors provides an effective tool for the generation and reactions of aryllithiums bearing an alkoxycarbonyl group at para-, meta-, and ortho-positions. Alkyl p- and m-lithiobenzoates were generated by the I/Li exchange reaction with PhLi. The Br/Li exchange reactions with sBuLi were unsuccessful. Subsequent reactions of the resulting aryllithiums with electrophiles gave the desired products in good yields. On the other hand, alkyl o-lithiobenzoates were successfully generated by the Br/ Li exchange reaction with sBuLi. Subsequent reactions with electrophiles gave the desired products in good yields.
- Nagaki, Aiichiro,Kim, Heejin,Moriwaki, Yuya,Matsuo, Chika,Yoshida, Jun-Ichi
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supporting information; experimental part
p. 11167 - 11177
(2010/11/04)
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- Cross-coupling reactions through the intramolecular activation of Alkyl(triorgano)silanes
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(Figure Presented) Cross-Si-ing the Jordan: Cross-coupling reactions of 2-(2-hydroxyprop-2-yl)phenylsubstituted alkylsilanes with a variety of aryl halides proceed in the presence of palladium and copper catalysts. The use of K3PO4 base allows for highly chemoselective alkyl coupling with both primary and secondary alkyl groups (Alk).
- Nakao, Yoshiaki,Takeda, Masahide,Matsumoto, Takuya,Hiyama, Tamejiro
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supporting information; scheme or table
p. 4447 - 4450
(2010/08/19)
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- Dendritically encapsulated, water-soluble Fe4S4: Synthesis and electrochemical properties
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Amphiphilic, Fe4S4 cluster core dendrimers can be prepared via ligand exchange with dendrons containing carboxylic acid peripheral groups and a thiol focal group. These amphiphilic dendrons are more susceptible to oxidative disulfide
- Sharma, Anil K.,Kim, Namjin,Cameron, Christopher S.,Lyndon, Matthew,Gorman, Christopher B.
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experimental part
p. 5072 - 5078
(2010/08/21)
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- Esters as acylating reagent in a Friedel-Crafts reaction: Indium tribromide catalyzed acylation of arenes using dimethylchlorosilane
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(Chemical Equation Presented) The Friedel-Crafts acylation of arenes with esters by dimethylchlorosilane and 10 mol % of indium tribromide has been achieved. The key intermediate RCOOSi(Cl)Me2 is generated from alkoxy esters with the evolution of the corresponding alkanes. The scope of the alkoxy ester moiety was wide: tert-butyl, benzyl, allyl, and isopropyl esters were successful. In addition, we demonstrated the direct synthesis of the indanone intermediate 11 of salviasperanol from ester 10.
- Nishimoto, Yoshihiro,Babu, Srinivasarao Arulananda,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 9465 - 9468
(2009/04/06)
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- Asymmetric [1,2] Stevens rearrangement of (S)-N-benzylic proline-derived ammonium salts under biphasic conditions
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The Stevens rearrangement of (S)-N-benzylic proline-derived ammonium salt with cesium hydroxide in 1,2-dichloroethane is shown to proceed with a high degree of the N-to-C chirality transmission to afford the α-substituted proline derivatives in high enantio-purities. Copyright
- Tayama, Eiji,Nanbara, Shintaro,Nakai, Takeshi
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p. 478 - 479
(2007/10/03)
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- Parallel synthesis of an ester library for substrate mapping of esterases and lipases
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Use of solid-supported reagents simplified routine acylation of primary and secondary alcohols because it eliminated traditional purification. Using a parallel synthesizer, eight primary or secondary alcohols reacted with acid chloride in the presence of poly(4-vinylpyridine), which acted as a base and acylation catalyst. Filtration, subsequent addition of amino-functionalized silica gel to remove excess acid chloride and a second filtration affording the corresponding esters in high yield (70-98%), excellent chemical purity (93-99%). Acylation of enantiopure alcohols yielded enantiopure esters. Acylation of two tertiary alcohols gave esters in low yield (27-57%) and variable chemical purity (57-99%).
- Morley, Krista L.,Magloire, Vladimir P.,Guerard, Christine,Kazlauskas, Romas J.
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p. 3005 - 3009
(2007/10/03)
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- Matrix metalloproteinase inhibitors
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Compounds are provided that bind allosterically to the catalytic domain of MMP-13 and comprise a hydrophobic group, first and second hydrogen bond acceptors and at least one, and preferably both, of a third hydrogen bond acceptor and a second hydrophobic group. Cartesian coordinates for centroids of the above features are defined in the specification. When the ligand binds to MMP-13, the first, second and third (when present) hydrogen bond acceptors bond respectively with Thr245, Thr 247 and Met 253, the first hydrophobic group locates within the S1' channel of MMP-13 and the second hydrophobic group (when present) is relatively open to solvent. The compounds specifically inhibit the matrix metalloproteinase-13 enzyme and thus are useful for treating diseases resulting from tissue breakdown, such as heart disease, multiple sclerosis, arthritis, atherosclerosis, and osteoporosis.
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- Parallel synthesis of glycomimetic libraries: targeting a C-type lectin.
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We have developed methods for the parallel synthesis of two libraries of non-carbohydrate-based analogues of mannose on a solid support. The natural product shikimic acid was used as a key building block. The ability of the compounds to block the binding of the C-type lectin MBP-A to a mannosylated surface was assessed in a high-throughput assay. Ten library members with inhibitory activities equivalent to that of alpha-methyl mannopyranoside were identified. [reaction: see text]
- Schuster, Michael C,Mann, David A,Buchholz, Tonia J,Johnson, Kathryn M,Thomas, William D,Kiessling, Laura L
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p. 1407 - 1410
(2007/10/03)
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- Pseudopeptide compounds having an inhibiting activity with respect to paths activated by proteins with active tyrosine kinase activity and pharmaceutical compositions containing same
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The invention concerns a compound corresponding to general formula (1) wherein, in particular, R2 represents a phenylmethyl or naphthylmethyl or cyclohexylmethyl radical, 2- and 3-pryidinylmethyl, substituted on the cycle in meta or para positi
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- An oxidative transformation of N′-phenylhydrazide to t-butyl ester using a copper(II) halide-lithium t-butoxide system
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Reactions of hydrazides or N1-phenylhydrazides with a copper(II) reagent prepared from copper(II) bromide and lithium t-butoxide smoothly proceeded to give the corresponding t-butyl ester in high yield.
- Yamaguchi, Jun-Ichi,Aoyagi, Takashi,Fujikura, Ryohei,Suyama, Takayuki
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p. 466 - 467
(2007/10/03)
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- Catalytic processes of oxidation by hydrogen peroxide in the presence of Br2 or HBr. Mechanism and synthetic applications
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The mechanism and the synthetic applications for the oxidation of alcohols, ethers, and aldehydes by H2O2 catalyzed by Bf2 or Br- in a liquid two-phase system (aqueous and organic) are reported. Aliphatic and benzylic primary alcohols and ethers show an opposite behavior, which has been rationalized on the ground of the different electronic configurations of the intermediate alkyl (π-type) and acyl (σ-type) radicals and their influence on enthalpic and polar effects. A two-phase system is particularly useful also for an efficient benzylic bromination by Br2 or Br-; the substitution of the benzyl bromide by OH, OR, and OCOR regenerates Br-, which can be recycled. The evaluation of the relative reactivities of the involved substrates and intermediates has allowed to develop a variety of simple, facile, convenient, and selective syntheses of alcohols, aldehydes, ketones, esters, and benzyl bromides, which fulfill the conditions for practical applications.
- Amati, Alessandro,Dosualdo, Gabriele,Zhao, Lihua,Bravo, Anna,Fontana, Francesca,Minisci, Francesco,Bjorsvik, Hans-Rene
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p. 261 - 269
(2013/09/08)
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- Convenient preparations of t-butyl esters and ethers from t-butanol
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A one-pot preparation of t-butyl esters and ethers is described that proceeds from the carboxylic acid or alcohol and t-butanol using only anhydrous magnesium sulfate and catalytic sulfuric acid as additional reagents. The method affords t-butyl esters and ethers in good yields and is applicable to a variety of substrates.
- Wright, Stephen W.,Hageman, David L.,Wright, Ann S.,McClure, Lester D.
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p. 7345 - 7348
(2007/10/03)
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- Dynamics of bond breaking in ion radicals. Mechanisms and reactivity in the reductive cleavage of carbon-fluorine bonds of fluoromethylarenes
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The reductive cleavage mechanism and reactivity of the carbon-fluorine bonds in fluoromethylarenes are investigated, in liquid ammonia and in DMF, by means of cyclic voltammetry and/or redox catalysis as a function of the number of fluorine atoms and of the structure of the aryl moiety. The reduction of the trifluoro compounds, eventually leading to complete defluorination, involves the di- and monofluoro derivatives as intermediates. Carbenes do not transpire along the reaction pathway. Application of the intramolecular dissociative electron transfer model allows the quantitative rationalization, in terms of driving force and intrinsic barrier, of the variation of the cleavage reactivity of the primary anion radical with the number of fluorine atoms and of the structure of the aryl moiety as well as with the solvating properties of the medium. When, related to the structural factors thus uncovered, the primary anion radical generates the di- and monofluoro intermediates far from the electrode surface, their reduction occurs homogeneously giving rise to an apparently direct six-electron process according to an internal redox catalysis mechanism. Conversely, with rapid cleavages, the reduction of the di- and monofluoro intermediates takes place at the electrode surface and the stepwise expulsion of the fluorides ions transpire in the cyclic voltammetric patterns.
- Andrieux, Claude P.,Combellas, Catherine,Kanoufi, Fredéric,Savéant, Jean-Michel,Thiébault, André
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p. 9527 - 9540
(2007/10/03)
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- Stereospecific synthesis of 4-carboxyphenylalanine and derivatives for use in Fmoc-based solid-phase peptide synthesis
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Starting from N(α)-benzyloxycarbonyl-L-tyrosine(O-triflate) benzyl ester, we have prepared enantiomerically pure 4-carboxyphenylalanine and 4-methoxycarbonylphenylalanine derivatives using palladium (0) catalyzed carbonylation reactions. These unnatural amino acids were suitably protected and were used in solid-phase peptide synthesis using the Fmoc/t-butyl approach.
- Wang, Wei,Obeyesekere, Nihal U.,McMurray, John S.
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p. 6661 - 6664
(2007/10/03)
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- Reactions of Carboxylic Acids with "Phosphonium Anhydrides"
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General considerations are outlined for a reagent to extract oxygen from organic molecules by an equivalent of dehydration.Reagents, (R3P+)2O, 2OTf-, were created for the purpose and subjected to a preliminary study.They were found to convert carboxylic acids readily and rapidly to anhydrides, esters, amides, amidines, benzimidazoles, and cyclic aryl ketones in good yields.
- Hendrickson, James B.,Hussoin, Md. Sajjat
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p. 1144 - 1149
(2007/10/02)
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- (6R,6S)-5,8,10-Trideaza-5,6,7,8-tetrahydrofolate and (6R,6S)-5,8,10-Trideaza-5,6,7,8-tetrahydropteroyl-L-ornithine as Potential Antifolates and Antitumor Agents
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(6R,6S)-5,8,10-Trideaza-5,6,7,8-tetrahydropteroic acid was synthesized in several steps from 4,4-(ethylenedioxy)cyclohexanone and triphenylphosphonium bromide and was elaborated to (6R,6S)-5,8,10-trideaza-5,6,7,8-tetrahydr
- Rosowsky, Andre,Forsch, Ronald A.,Moran, Richard G.
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p. 709 - 715
(2007/10/02)
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