- Homoenolic radical derived from propionic acid: A versatile reagent for the radical version of the Michael reaction
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The homoenolic radical, derived from 3-iodopropionic acid (1) by reaction with in situ generated tributyltin hydride, undergoes clean carbon-carbon forming reaction with electrophilic olefins (2) yielding functionalized acids (3).
- Foubelo,Lloret,Yus
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Read Online
- Pd-Catalyzed Regioselective Branched Hydrocarboxylation of Terminal Olefins with Formic Acid
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A regioselective Pd-catalyzed hydrocarboxylation of terminal olefins with HCOOH is described. A wide variety of branched carboxylic acids can readily be obtained with high regioselectivities under mild reaction conditions. The reaction is operationally simple and requires no handling of toxic CO. The ligand and LiCl are important factors for reaction reactivity and selectivity.
- Chu, Jianxiao,Guo, Jianqiong,Ren, Wenlong,Shi, Yian,Shi, Yuan,Wang, Mingzhou,Zhou, Jintao
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supporting information
p. 886 - 891
(2022/02/07)
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- Synthesis of Carboxylic Acids by Palladium-Catalyzed Hydroxycarbonylation
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The synthesis of carboxylic acids is of fundamental importance in the chemical industry and the corresponding products find numerous applications for polymers, cosmetics, pharmaceuticals, agrochemicals, and other manufactured chemicals. Although hydroxycarbonylations of olefins have been known for more than 60 years, currently known catalyst systems for this transformation do not fulfill industrial requirements, for example, stability. Presented herein for the first time is an aqueous-phase protocol that allows conversion of various olefins, including sterically hindered and demanding tetra-, tri-, and 1,1-disubstituted systems, as well as terminal alkenes, into the corresponding carboxylic acids in excellent yields. The outstanding stability of the catalyst system (26 recycling runs in 32 days without measurable loss of activity), is showcased in the preparation of an industrially relevant fatty acid. Key-to-success is the use of a built-in-base ligand under acidic aqueous conditions. This catalytic system is expected to provide a basis for new cost-competitive processes for the industrial production of carboxylic acids.
- Sang, Rui,Kucmierczyk, Peter,Dühren, Ricarda,Razzaq, Rauf,Dong, Kaiwu,Liu, Jie,Franke, Robert,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 14365 - 14373
(2019/09/06)
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- Pd-Catalyzed Highly Chemo- And Regioselective Hydrocarboxylation of Terminal Alkyl Olefins with Formic Acid
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An efficient Pd-catalyzed hydrocarboxylation of alkenes with HCOOH is described. A wide variety of linear carboxylic acids bearing various functional groups can be obtained with excellent chemo- and regioselectivities under mild reaction conditions. The reaction process is operationally simple and requires no handling of toxic CO.
- Ren, Wenlong,Chu, Jianxiao,Sun, Fei,Shi, Yian
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supporting information
p. 5967 - 5970
(2019/08/26)
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- Synthetic method of terminal carboxylic acid
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The invention discloses a synthetic method of a terminal carboxylic acid. The synthetic method is characterized by comprising the steps of adding an olefin represented by a formula (3) shown in the description, formic acid, acetic anhydride, Pd(OAc)2 and a monophosphorus ligand TFPP into an organic solvent in a proportion, carrying out hydrogen carbonylation reaction on the olefin represented by the formula (3) shown in the description, formic acid and acetic anhydride at 80-90 DEG C for 48h-72h under the catalysis of the metal palladium salt Pd(OAc)2 and the monophosphorus ligand TFPP so as to obtain the terminal carboxylic acid represented by a formula shown in the description, and separating a target product, namely the terminal carboxylic acid after the reaction is finished, wherein olefin represented by the formula (3) is selected from cycloolefins, or linear olefins of which the R1 is electron donating groups. By virtue of the method disclosed by the invention, corresponding terminal carboxylic acid and a derivative thereof can be prepared through the reaction under mild conditions of low temperature and no high pressure; and the steps of the synthetic method are simple and convenient, the operation is convenient, the yield is high, the energy source can be greatly saved, and the synthetic efficiency can be greatly improved.
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Paragraph 0051-0054
(2019/11/21)
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- Strategic Approach to the Metamorphosis of γ-Lactones to NH γ-Lactams via Reductive Cleavage and C-H Amidation
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A new approach has elaborated on the conversion of γ-lactones to the corresponding NH γ-lactams that can serve as γ-lactone bioisosteres. This approach consists of reductive C-O cleavage and an Ir-catalyzed C-H amidation, offering a powerful synthetic tool for accessing a wide range of valuable NH γ-lactam building blocks starting from γ-lactones. The synthetic utility was further demonstrated by the late-stage transformation of complex bioactive molecules and the asymmetric transformation.
- Jung, Hoi-Yun,Chang, Sukbok,Hong, Sungwoo
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supporting information
p. 7099 - 7103
(2019/09/07)
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- Carbonylative Transformation of Allylarenes with CO Surrogates: Tunable Synthesis of 4-Arylbutanoic Acids, 2-Arylbutanoic Acids, and 4-Arylbutanals
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In this Communication, procedures for the selective synthesis of 4-arylbutanoic acids, 2-arylbutanoic acids, and 4-arylbutanals from the same allylbenzenes have been developed. With formic acid or TFBen as the CO surrogate, reactions proceed selectively and effectively under carbon monoxide gas-free conditions.
- Wu, Fu-Peng,Li, Da,Peng, Jin-Bao,Wu, Xiao-Feng
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supporting information
p. 5699 - 5703
(2019/08/01)
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- CATALYTIC CARBOXYLATION OF ACTIVATED ALKANES AND/OR OLEFINS
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The present invention relates to a method of reacting starting materials with an activating group, namely alkanes carrying a leaving group and/or olefins, with carbon dioxide under transition metal catalysis to give carboxyl group-containing products. It is a special feature of the method of the present invention that the carboxylation predominantly takes place at a preferred position of the molecule irrespective of the position of the activating group. The carboxylation position is either an aliphatic terminus of the molecule or it is a carbon atom adjacent to a carbon carrying an electron withdrawing group. The course of the reaction can be controlled by appropriately choosing the reaction conditions to yield the desired regioisomer.
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Page/Page column 65; 66
(2018/02/28)
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- Synthetic Applications and Mechanistic Studies of the Hydroxide-Mediated Cleavage of Carbon-Carbon Bonds in Ketones
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The hydroxide-mediated cleavage of ketones into alkanes and carboxylic acids has been reinvestigated and the substrate scope extended to benzyl carbonyl compounds. The transformation is performed with a 0.05 M ketone solution in refluxing xylene in the presence of 10 equiv of potassium hydroxide. The reaction constitutes a straightforward protocol for the synthesis of certain phenyl-substituted carboxylic acids from 2-phenylcycloalkanones. The mechanism was investigated by kinetic experiments which indicated a first order reaction in hydroxide and a full negative charge in the rate-determining step. The studies were complemented by a theoretical investigation where two possible pathways were characterized by DFT/M06-2X. The calculations showed that the scission takes place by nucleophilic attack of hydroxide on the ketone followed by fragmentation of the resulting oxyanion into the carboxylic acid and a benzyl anion.
- Mazziotta, Andrea,Makarov, Ilya S.,Fristrup, Peter,Madsen, Robert
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p. 5890 - 5897
(2017/06/07)
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- Site-Selective Catalytic Carboxylation of Unsaturated Hydrocarbons with CO2 and Water
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A catalytic protocol that reliably predicts and controls the site-selective incorporation of CO2 to a wide range of unsaturated hydrocarbons utilizing water as formal hydride source is described. This platform unlocks an opportunity to catalytically repurpose three abundant, orthogonal feedstocks under mild conditions.
- Gaydou, Morgane,Moragas, Toni,Juliá-Hernández, Francisco,Martin, Ruben
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supporting information
p. 12161 - 12164
(2017/09/12)
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- Hydrogen-transfer reduction of α,β-unsaturated carbonyl compounds catalyzed by naphthyridine-functionalized N-heterocyclic carbene complexes
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Substitution of silver complex of 2-chloro-7-(mesitylimidazolylidenylmethyl)naphthyridine (NpNHC) with palladium(II), rhodium(I) and iridium(I) metal precursors provided [Pd(C,N-NpNHC)(η3-allyl)](BF4) (5), RhCl(COD)(C-NpNHC) (6a) and IrCl(COD)(C-NpNHC) (6b), respectively. Abstraction of chloride from 6a and 6b with AgBF4 provided the chelation complexes [Rh(COD)(C,N-NpNHC)](BF4) (7a) and Ir(COD)(C,N-NpNHC)(BF4) (7b), respectively. All complexes were characterized using NMR and elemental analyses and the structural details of 5 and 6a were further confirmed using X-ray crystallography. In catalytic activity studies, complex 5 was found to be an effective catalyst in the hydrogen-transfer reduction of α,β-unsaturated carbonyl compounds into the corresponding saturated carbonyl compounds.
- Huang, Hsiao-Ching,Ramanathan, Mani,Liu, Yi-Hong,Peng, Shie-Ming,Liu, Shiuh-Tzung
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- Remote carboxylation of halogenated aliphatic hydrocarbons with carbon dioxide
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Catalytic carbon-carbon bond formation has enabled the streamlining of synthetic routes when assembling complex molecules. It is particularly important when incorporating saturated hydrocarbons, which are common motifs in petrochemicals and biologically relevant molecules. However, cross-coupling methods that involve alkyl electrophiles result in catalytic bond formation only at specific and previously functionalized sites. Here we describe a catalytic method that is capable of promoting carboxylation reactions at remote and unfunctionalized aliphatic sites with carbon dioxide at atmospheric pressure. The reaction occurs via selective migration of the catalyst along the hydrocarbon side-chain with excellent regio- and chemoselectivity, representing a remarkable reactivity relay when compared with classical cross-coupling reactions. Our results demonstrate that site-selectivity can be switched and controlled, enabling the functionalization of less-reactive positions in the presence of a priori more reactive ones. Furthermore, we show that raw materials obtained in bulk from petroleum processing, such as alkanes and unrefined mixtures of olefins, can be used as substrates. This offers an opportunity to integrate a catalytic platform en route to valuable fatty acids by transforming petroleum-derived feedstocks directly.
- Juliá-Hernández, Francisco,Moragas, Toni,Cornella, Josep,Martin, Ruben
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- COMPOUNDS FOR INHIBITING LIPID OXIDATION AND A METHOD FOR PRODUCING THE SAME
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The present invention relates to a compound for inhibiting lipid oxidation, and a producing method thereof. The compound for inhibiting lipid oxidation is synthesized by a transesterification reaction though a vinyl reaction and a lipase-catalyzed reaction. The produced compound for inhibiting lipid oxidation has an excellent effect of inhibiting oxidation according to a total oxidation value (TOTOX) which is a combination of a P-anisidine value (P-AnV) and a peroxide value (PV) and an analysis of a thiobarbituric acid reaction substance (TBARS).COPYRIGHT KIPO 2016
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Paragraph 0135-0136; 0143
(2017/05/03)
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- Three-component, one-pot synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives under catalyst free conditions and evaluation of their anti-inflammatory activity
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An efficient three-component protocol is described for the synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives using β-chloroacroleins, 1,3-dicarbonyls and ammonium acetate under catalyst free conditions by using ethanol as reaction media. The mild reaction conditions, operational simplicity and high yields are the advantages of this protocol and the broad scope of this one-pot reaction makes this procedure promising for practical usages. All the final compounds were screened for anti-inflammatory activity. Among the compounds tested, the compounds 5a, 5b, 5c, 5d, 5f, and 5k exhibited significant inhibition of IL-1β and MCP-1 secretion as a measure of anti-inflammatory activity.
- Sajja, Yasodakrishna,Vulupala, Hanmanth Reddy,Bantu, Rajashaker,Nagarapu, Lingaiah,Vasamsetti, Sathish Babu,Kotamraju, Srigiridhar,Nanubolu, Jagadeesh Babu
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p. 858 - 863
(2016/05/24)
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- Highly enantioselective [3+2] coupling of cyclic enamides with quinone monoimines promoted by a chiral phosphoric acid
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Enantioselective [3+2] coupling of cyclic enamides with quinone monoimines was realised using a chiral phosphoric acid as a catalyst. This transformation allowed for the synthesis of highly enantioenriched polycyclic 2,3-dihydrobenzofurans (up to 99.9% ee). The absolute configuration of one product was determined by an X-ray crystal structural analysis. We also found a possible mechanism for this reaction.
- Zhang, Minmin,Yu, Shuowen,Hu, Fangzhi,Liao, Yijun,Liao, Lihua,Xu, Xiaoying,Yuan, Weicheng,Zhang, Xiaomei
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supporting information
p. 8757 - 8760
(2016/07/15)
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- Cp2TiCl2-Catalyzed Regioselective Hydrocarboxylation of Alkenes with CO2
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Cp2TiCl2-catalyzed regioselective hydrocarboxylation of alkenes with CO2 to give carboxylic acids in high yields has been developed in the presence of iPrMgCl. The reaction proceeds with a wide range of alkenes under mild conditions. Styrene and its derivatives can transform to α-aryl carboxylic acids, and aliphatic alkenes can transform to form alkanoic acids.
- Shao, Peng,Wang, Sheng,Chen, Chao,Xi, Chanjuan
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supporting information
p. 2050 - 2053
(2016/06/01)
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- SUBSTITUTED BENZOXAZOLONE DERIVATIVES AS ACID CERAMIDASE INHIBITORS, AND THEIR USE AS MEDICAMENTS
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The present invention relates to substituted benzoxazolone derivatives as acid ceramidase inhibitors, pharmaceutical compositions containing these inhibitors and methods of inhibiting acid ceramidase for the treatment of disorders in which modulation of the levels of ceramide is clinically relevant. The invention also provides substituted benzoxazolone derivatives for use in the treatment of cancer, inflammation, pain, inflammatory pain or pulmonary diseases.
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Page/Page column 22; 41; 48
(2015/12/31)
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- Ketyl-type radicals from cyclic and acyclic esters are stabilized by SmI2(H2O)n: the role of SmI2(H 2O)n in post-electron transfer steps
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Mechanistic details pertaining to the SmI2-H2O- mediated reduction and reductive coupling of 6-membered lactones, the first class of simple unactivated carboxylic acid derivatives that had long been thought to lie outside the reducing range of SmI2, have been elucidated. Our results provide new experimental evidence that water enables the productive electron transfer from Sm(II) by stabilization of the radical anion intermediate rather than by solely promoting the first electron transfer as originally proposed. Notably, these studies suggest that all reactions involving the generation of ketyl-type radicals with SmI2 occur under a unified mechanism based on the thermodynamic control of the second electron transfer step, thus providing a blueprint for the development of a broad range of novel chemoselective transformations via open-shell electron pathways.
- Szostak, Michal,Spain, Malcolm,Procter, David J.
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supporting information
p. 8459 - 8466
(2014/06/24)
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- Transition-metal-free and chemoselective NaOtBu-O 2-mediated oxidative cleavage reactions of vic-1,2-diols to carboxylic acids and mechanistic insight into the reaction pathways
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A method for efficient oxidative cleavage of vic-1,2-diols using a NaO tBu-O2 system resulted in the formation of carboxylic acids in high yields. The present protocol is an eco-friendly alternative to a conventional transition-metal-based method. This new strategy allows large-scale production with nonchromatographic purification while also suppressing competitive reaction pathway such as benzilic acid rearrangement.
- Kim, Sun Min,Kim, Dong Wan,Yang, Jung Woon
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p. 2876 - 2879
(2014/06/23)
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- Synthesis of novel building blocks of benzosuberone bearing coumarin moieties and their evaluation as potential anticancer agents
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A series of novel benzosuberone bearing coumarin moieties 5a-c have been synthesized and their structures were determined by analytical and spectral (FT-IR, 1H NMR, 13C NMR, HRMS) studies. The newly synthesized compounds were evaluated for their cytotoxicity against four human cancer cell lines, A549 (Human alveolar adenocarcinoma cell line), HeLa (Human cervical cancer cell line), MDA-MB-231 (Human breast adenocarcinoma cell line), MCF-7 (Human breast adenocarcinoma cell line) and normal cell line HEK293 (Human embryonic kidney cell line). Compound 5a exhibited promising cytotoxicity with IC50 values ranging from 3.35 to 16.79 μM against all the cancer cell lines like A549, HeLa, MCF-7 and MDA-MB-231, while compound 5c showed significant cytotoxicity against HeLa and MDA-MB-231 with IC50 values of 6.72 and 4.87, respectively.
- Yadagiri, Bandi,Holagunda, Uma Devi,Bantu, Rajashaker,Nagarapu, Lingaiah,Kumar, C. Ganesh,Pombala, Sujitha,Sridhar
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p. 260 - 265
(2014/05/06)
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- Ni-catalyzed carboxylation of unactivated primary alkyl bromides and sulfonates with CO2
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A Ni-catalyzed carboxylation of unactivated primary alkyl bromides and sulfonates with CO2 at atmospheric pressure is described. The method is characterized by its mild conditions and remarkably wide scope without the need for air- or moisture-sensitive reagents, which make it a user-friendly and operationally simple protocol en route to carboxylic acids.
- Liu, Yu,Cornella, Josep,Martin, Ruben
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p. 11212 - 11215
(2014/09/30)
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- Scope and limitations of auxiliary-assisted, palladium-catalyzed arylation and alkylation of sp2 and sp3 C-H bonds
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The scope of palladium-catalyzed, auxiliary-assisted direct arylation and alkylation of sp2 and sp3 C-H bonds of amine and carboxylic acid derivatives has been investigated. The method employs a palladium acetate catalyst, substrate, aryl, alkyl, benzyl, or allyl halide, and inorganic base in tert-amyl alcohol or water solvent at 100-140 C. Aryl and alkyl iodides as well as benzyl and allyl bromides are competent reagents in this transformation. The picolinic acid auxiliary is used for amine γ-functionalization, and the 8-aminoquinoline auxiliary is used for carboxylic acid β-functionalization. Some optimization of base, additives, and solvent is required for achieving best results.
- Nadres, Enrico T.,Santos, Gerson Ivan Franco,Shabashov, Dmitry,Daugulis, Olafs
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p. 9689 - 9714
(2013/10/22)
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- Peptide/laccase cocatalyzed asymmetric α-oxyamination of aldehydes
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An asymmetric α-oxyamination could be successfully performed by a peptide catalyst and laccase. The combination of peptide catalysis and enzymatic air oxidation promoted the reaction smoothly in water without employing a metal reagent. The oxyaminated compounds could be obtained as both aldehyde and carboxylic acid products depending on the reaction conditions.
- Akagawa, Kengo,Kudo, Kazuaki
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scheme or table
p. 3498 - 3501
(2011/09/14)
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- The non-metathetic role of Grubbs' carbene complexes: From hydrogen-free reduction of α,β-unsaturated alkenes to solid-supported sequential cross-metathesis/reduction
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An efficient and high-yielding "hydrogen-free" reduction of α,β-unsaturated alkenes was carried out employing Grubbs' catalyst in a non-metathetic role and Et3SiH. Conditions were optimized under microwave irradiation. Application to the solid-phase organic synthesis allows a facile construction of sp3-sp3 carbon bonds through a sequential cross metathesis/olefin reduction.
- Poeylaut-Palena, Andres A.,Testero, Sebastian A.,Mata, Ernesto G.
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supporting information; experimental part
p. 1565 - 1567
(2011/03/20)
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- One-pot conversion of alkyl aldehydes into substituted propanoic acids via Knoevenagel condensation with Meldrum's acid
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Reaction of a range of alkyl aldehydes and Meldrum's acid in triethylammonium formate (TEAF) at 100 °C generates substituted propanoic acids in a single step.
- Mudhar, Harminder,Witty, Andrew
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experimental part
p. 4972 - 4974
(2011/01/12)
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- Fe-Cu cooperative catalysis in the isomerization of alkyl Grignard reagents
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Alkyl Grignard reagents were found to be isomerized to more stable ones in high isomerization ratios (>99%) under cooperative catalysis by iron and copper, which promote isomerization of alkyl groups and transmetalation between Fe-Mg, respectively. The Ro
- Shirakawa, Eiji,Ikeda, Daiji,Yamaguchi, Shigeru,Hayashi, Tamio
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p. 1214 - 1216
(2008/12/21)
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- TEMPO-mediated environmentally benign oxidation of primary alcohols to carboxylic acids with poly[4-(diacetoxyiodo)styrene]
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An operationally simple and environmentally benign oxidation of primary alcohols to the corresponding carboxylic acids with a TEMPO-mediated poly[4-(diacetoxyiodo)styrene] system in acetone and water was carried out.
- Tashino, Yousuke,Togo, Hideo
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p. 2010 - 2012
(2007/10/03)
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- Synthesis and cross-coupling reactions of solid-supported alkylzinc reagents
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Hydroboration of Wang-supported pent-4-enoic acid 1, followed by transmetallation with Et2Zn, gives a solid-supported zinc reagent, 2, which undergoes palladium-catalysed coupling with aryl iodides, to give the corresponding 5-arylpentanoic acids 3 in moderate to good yields, after cleavage from the resin using TFA.
- Jackson, Richard F. W.,Oates, Leslie J.,Block, Michael H.
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p. 1401 - 1402
(2007/10/03)
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- Diaziridinyl-aryl and bis-[di(chloroethyl)amino]-aryl oligonucleotide conjugates and reagents for making the same
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Diaziridinyl-aryl and bis-[di(chloroethyl)amino]-aryl oligonucleotide conjugates have a sequence that is complementary in the triplex forming sense to a target sequence in duplex nucleic acid. The diaziridinyl-aryl and bis-[di(chloroethyl)amino]-aryl oligonucleotide conjugates effectively cross-link with both strands of the targeted duplex nucleic acid.
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- Conjugate addition of a primary carbon radical to α,β-unsaturated carboxylic acids
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Triethylborane in the presence of trace oxygen was employed simultaneously as a radical initiator and carboxyl protecting group to promote the conjugate radical addition of 2-phenethyl iodide to α,β- unsaturated carboxylic acids in good yields. (C) 2000 Elsevier Science Ltd.
- Wu, Baogen,Avery, Bonnie A.,Avery, Mitchell A.
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p. 3797 - 3800
(2007/10/03)
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- Generation of nitrile oxides from oxime derivatives by the oxidation with ammonium hexanitratocerate(IV)
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Aromatic and aliphatic nitrile oxides are generated by the oxidation of α-hydroxyimino carboxylic acid with ammonium hexanitratocerate(IV). They react with olefinic and acetylenic dipolarophiles to give the corresponding cycloaddition products in good yield. The oxidation of α-oxo aldoximes also affords α-oxo carbonitrile oxides.
- Arai, Noriyoshi,Iwakoshi, Mitsuhiko,Tanabe, Katsuhiko,Narasaka, Koichi
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p. 2277 - 2285
(2007/10/03)
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- Integrated chemical process: One-pot aromatization of cyclic enones by the double elimination methodology
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A variety of aromatic hydrocarbons bearing multiple alkyl substituents are accessible with perfect regiocontrol in a one-pot reaction starting from cyclo-hexenones and their aromatic analogues [Eq. (1)]. The present methodology can be further extended to the synthesis of polycyclic aromatic hydrocarbons. The drawbacks encountered in the Friedel-Crafts reaction are resolved since the reaction proceeds under basic conditions.
- Orita, Akihiro,Yaruva, Jayamma,Otera, Junzo
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p. 2267 - 2270
(2007/10/03)
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- Remote stereocontrol as a synthetic strategy: Diastereoselective annulations on an arene tricarbonylchromium template
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Stereoselective annulations on Cr(CO)3 complexed tetralone and benzosuberone derivatives have been achieved. Diastereomeric products are shown to be related by an epimerisable chiral centre. An unusually facile de-ethoxycarbonylation has been observed.
- Sur, Surojit,Ganesh, Sambasivam,Puranik, Vedavati G.,Sarkar, Amitabha
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p. 977 - 982
(2007/10/03)
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- Acidity and stability of 10-substituted 1,8-dihydroxy-9(10H)-anthracenones
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The decomposition of 10-substituted anthralin derivatives in dimethyl sulfoxide and ethanol was determined. While 10-ω-phenylalkylidene derivatives were thoroughly stable, 10-ω-phenylacyl-substituted compounds were slowly degraded to danthron and the corresponding carboxylic acids. However, the stability of these derivatives was markedly improved as compared to that of anthralin. Determination of the pK(a) values showed that the ω-phenylacyl derivatives were somewhat stronger acids than anthralin, while ω-phenylalkylidene-substitution generally leaves the acidity of the anthralin part unchanged.
- Muller,Gawlik,Wiegrebe
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p. 359 - 362
(2007/10/02)
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- Quantitative Analyses of Biochemical Kinetic Resolution of Enantiomers. 2. Enzyme-Catalyzed Esterification in Water-Organic Solvent Biphasic Systems
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New quantitative expressions, which relate the kinetic and thermodynamic parameters that govern the stereospecificity of enzyme-catalyzed resolution of enantiomers in biphasic aqueous-organic media, have been developed.The theoretical predictions have been verified experimentally, and the technical merit of this esterification methodology has been assessed in relation to the more conventional hydrolytic procedure.
- Chen, Ching-Shih,Wu, Shih-Hsiung,Girdaukas, Gary,Sih, Charles J.
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p. 2812 - 2817
(2007/10/02)
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- STUCTURE AND SYNTHESIS OF WF 3681, A NOVEL ALDOSE REDUCTASE INHIBITOR
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The structure of WF 3681 (1), an aldose reductase inhibitor isolated from a Chaetomella species, has been determined on the basis of its physical and chemical properties and confirmed by a total synthesis.
- Uchida, Itsuo,Itoh, Yoshikuni,Namiki, Takayuki,Nishikawa, Motoaki,Hashimoto, Masashi
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p. 2015 - 2018
(2007/10/02)
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- Aspects of Tautomerism. 13. Alkaline Hydrolysis of γ-, δ-, and ε-Keto Esters and their Desoxy Analogues. Geometrical Constraints on Keto Participation
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The rates of alkaline hydrolysis of methyl β-benzoylpropionate (I), methyl γ-benzoylbutyrate (II) and methyl δ-benzoylvalerate (III) decrease in the order I>II>III.Keto participation is the predominant pathway in the case of γ-keto esters.Evidence has also been obtained for keto participation in the case of δ-keto esters, whereas no such evidence is available in the case of ε-keto esters studied.
- Bhatt, M. Vivekananda,Ravindranathan, M.,Somayaji, Viswanatha,Rao, G. Venkoba
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p. 3170 - 3173
(2007/10/02)
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- Deecomposition homolytique du peracide pheenyl-5 pentanoique: reeactivitee du radical pheenyl-4 butyle et compeetition entre deux meecanismes en chaine
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5-Phenyl pentanoic peracid decomposes in boiling cyclohexane solution to the corresponding acid instead of decarboxylation as is observed for the related cases.This difference in behaviour is explained by the cyclization of the 4-phenyl butyl radical which can then no longer propagate any chain rection leading to 4-phenyl butanol.The peracid, therefore reacts by a competitive radical chain mechanism leading to the corresponding acid.
- Nedelec, Jean-Yves,Fossey, Jacques,Lefort, Daniel,Sorba, Jeanine
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p. 2317 - 2319
(2007/10/02)
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- A Convenient Reduction of Activated Olefins by Zinc-Copper Couple
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Activated olefins of the types Ph2C=CXY, R2C=CXY, PhRC=CXY, and RCH=CXY (where X and Y are electronegative substituents or one of them is a hydrogen atom) have been reduced to the corresponding saturated compounds in excellent yields by treatment with zinc-copper couple in boiling methanol.
- Sondengam, B. Lucas,Fomum, Z. Tanee,Charles, Georges,Akam, T. Mac
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p. 1219 - 1222
(2007/10/02)
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- EFFETS POLAIRES DANS LES REACTIONS DE TRANSFERT HOMOLYTIQUE INTRAMOLECULAIRE D'HYDROGENE
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In this paper we analyse the influence of a phenyl substituent on the relative rates of the 1-5 and 1-6 intramolecular hydrogen transfers.Compared to the abstraction of an aliphatic H atom, the activation energy for the abstraction of a benzylic H atom is smaller.The effect is nevertheless more important with a primary alkyl radical (1,3 kcal/mole) than with an alkoxy radical (0,9 kcal/mole).This can be analysed in terms of a polar effect.In addition, the size of the effect is too small to make a short distance transfer of a H atom feasible; this is in keeping with the statement that H atom migration requires a linear transition state.
- Lefort, D.,Nedelec, J. Y.
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p. 2681 - 2686
(2007/10/02)
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