- A facile and selective cleavage of prenyl esters catalyzed by CeCl3·7 H2O-NaI
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A highly selective cleavage of prenyl esters has been achieved in high yields using CeCl3·7 H2O-NaI in refluxing acetonitrile under neutral conditions. This method is mild and compatible with a wide variety of functional groups such
- Yadav,Subba Reddy,Venkateshwara Rao,Chand,Prasad
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Read Online
- Useful Direct Conversion of Tetrahydropyranyl Ethers of Fatty Alcohols into Fatty Acids
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Tetrahydro-2-pyranyl ethers from fatty primary alcohols can be converted in a one-step procedure into the corresponding carboxylic acids in high yields.This process avoids the synthesis of symmetrical esters, particularly for long-chain compounds.This reaction proved to be useful, for instance, to produce polyunsaturated fatty acids immediately before their biological testing. - Key words: Oxidation; polyunsaturated fatty acids; tetrahydropyranyl ethers
- Gruiec, Regine,Noiret, Nicolas,Patin, Henri
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- Interaction of oxygen functionalized alkenes with a methylaluminoxane-zirconocene catalyst studied by NMR
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Reactions of hydroxyl, ether and carbonyl functionalized alkenes with methylaluminoxane prepared in toluene-d8 (MAO) and zirconocenedichloride (Cp2ZrCl2) were investigated by 1H- and 13C-NMR spectroscopy at 27°C. The 11 alkenes studied bear a terminal C=C bond separated by 7-9 (-CH2-) units from the heteroatom moiety. Intramolecular connectivities in mono (alkene), bi (alkene and MAO) and tri (alkene, MAO and Cp2ZrCl2) component mixtures were determined by 2D HSQC, HMBC, ROESY and NOESY NMR techniques. The five studied alkenols formed aluminium alkoxides with MAO even in the case of a substantial steric hindrance around the OH group. Zirconocene enhanced the formation of aluminium alkoxides. Decomposition to free alkenol was observed only for the straight chain alkenol (10-undecen-1-ol). The OTMS derivatives formed dimers of the type CH2=CR1R2 along with methyl derivatives, CH2=C(Me)(R) and (Me)CH=CH(R), in the presence of MAO and Cp2ZrCl2. 10-Undecenyl methyl ether and methyl decenoate remained mainly as a free comonomer in the presence of MAO or MAO/Cp2ZrCl2, though a transient coordination of the former to MAO was deduced. Unsaturated species Me2C=CH-Al-X and CH2=CH(CH2)5CH2CH=C(t-Bu)O-Al-X (X = MAO oligomer) were formed in the reaction of t-butyl undecenoate or 2,2-dimethyl-11-dodecen-3-one with MAO or MAO/Cp2ZrCl2. Interaction of the CH2=CH part of the functionalized alkenes with zirconocene was not observed. A possible coordination of the C=C bond to MAO was observed only for the sec alkenols.
- Helaja, Tuulamari,Hakala, Kimmo,Helaja, Juho,Loefgren, Barbro
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- A simple, mild and efficient procedure for selective cleavage of prenyl esters using silica-supported sodium hydrogen sulphate as a heterogenous catalyst
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Prenyl esters were selectively and efficiently cleaved under slightly acidic reaction conditions using silica-supported sodium hydrogen sulfate as a heterogenous catalyst at room temperature to regenerate the parent carboxylic acids in very high yields.
- Ramesh,Mahender,Ravindranath,Das, Biswanath
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- A New and Efficient Synthesis of Trifluoromethyl Ketones from Carboxylic Acids. Part I.
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Trifluoromethyl ketones can be prepared in good yield from primary carboxylic acid chlorides by reaction with pyridine and trifluoroacetic anhydride followed by aqueous work up.
- Boivin, Jean,El Kaim, Laurent,Zard, Samir Z.
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- Bio-based α,ω-Functionalized Hydrocarbons from Multi-step Reaction Sequences with Bio- and Metallo-catalysts Based on the Fatty Acid Decarboxylase OleTJE
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OleT from Jeotgalicoccus sp. ATCC 8456 catalyzes the decarboxylation of ω-functionalized fatty acids to the corresponding alkenols, which can themselves serve as starting material for the synthesis of polymers and fine chemicals. To show the versatility of possible reactions, a series of in vitro reaction cascades was developed where an alkenol produced by the decarboxylation of ω-hydroxy fatty acids can be further converted into alkenylamines and diols. By coupling OleT with an alcohol dehydrogenase or alcohol oxidase as well as an amino-transaminase, an oxidative decarboxylation followed by the oxidation of the terminal alcohol and a subsequent reductive transamination could be carried out. By using different cofactors or electron sources, the reactions could be performed sequentially or simultaneously. The combination of enzymatic decarboxylation with a ruthenium catalyst in a chemo-enzymatic cascade provides a novel way to synthesize long-chain diols.
- Bojarra, Samiro,Reichert, Dennis,Grote, Marius,Baraibar, álvaro Gómez,Dennig, Alexander,Nidetzky, Bernd,Mügge, Carolin,Kourist, Robert
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- Oxidation of Primary Alcohols and Aldehydes to Carboxylic Acids via Hydrogen Atom Transfer
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The oxidation of primary alcohols and aldehydes to the corresponding carboxylic acids is a fundamental reaction in organic synthesis. In this paper, we report a new chemoselective process for the oxidation of primary alcohols and aldehydes. This metal-free reaction features a new oxidant, an easy to handle procedure, high isolated yields, and good to excellent functional group tolerance even in the presence of vulnerable secondary alcohols and tert-butanesulfinamides.
- Tan, Wen-Yun,Lu, Yi,Zhao, Jing-Feng,Chen, Wen,Zhang, Hongbin
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supporting information
p. 6648 - 6653
(2021/09/08)
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- Nitrogen-fixing of ultrasmall Pd-based bimetallic nanoclusters on carbon supports
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Synthesis of supported Pd-based bimetallic catalysts is of great importance in the heterogeneous catalysis field owing to their optimal geometric and electronic effects. Downsizing active metals to ultrasmall nanocluster (2-reduction at 400–500 °C. Through the nitrogen-fixing strategy, we prepare 9 sub-2 nm Pd-based bimetallic nanocluster catalysts by conventional impregnation process. The prepared supported bimetallic Pd-Pb nanocluster catalyst exhibit a high turnover frequency of 1092 h?1 for the semihydrogenation of phenylacetylene under a mild condition (30 °C, 5 bar H2), along with a high selectivity of >93% to styrene, demonstrating the alloying and small-size effects in the bimetallic nanocluster catalysts.
- Chen, Ping,Liang, Hai-Wei,Shen, Shan-Cheng,Wang, Lei,Xu, Shi-Long,Yin, Peng,Zhang, Le-Le
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p. 297 - 304
(2020/07/03)
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- Synthesis from Undecylenic Acid of Macroheterocycles with Diacylhydrazine and Ester Fragments
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A three-step synthesis of potentially biologically active 30- and 32-membered macroheterocycles with esters and acylhydrazines starting from methyl undecylenate was developed based on [1+1]-condensation of intermediate tetraesters, i.e., bis(10′ -methoxy-10′-oxodecyl)- or bis(11′-methoxy-11′ -oxoundecyl)hexanedioate, with hydrazine hydrate. The structures of the synthesized compounds were confirmed using IR and NMR spectroscopy and mass spectrometry.
- Mingaleeva,Yakovleva,Ishmuratov, G. Yu.
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p. 895 - 898
(2019/11/03)
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- Broadly Applicable Ytterbium-Catalyzed Esterification, Hydrolysis, and Amidation of Imides
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An efficient, broadly applicable, operationally simple, and divergent process for the transformation of imides into a range of carboxylic acid derivatives under mild conditions is reported. By simply using catalytic amounts of ytterbium(III) triflate as a Lewis acid promoter in the presence of alcohols, water, amines, or N,O-dimethylhydroxylamine, a broad range of imides is smoothly and readily converted to the corresponding esters, carboxylic acids, amides, and Weinreb amides in good yields. This method notably enables an easy cleavage of oxazolidinone-based auxiliaries.
- Guissart, Céline,Barros, Andre,Rosa Barata, Luis,Evano, Gwilherm
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p. 5098 - 5102
(2018/09/13)
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- Catalytic cracking preparing 10-cavity and enanthaldehyde method
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The invention relates to a process for producing polyundecancylamide resin through castor oil and particularly relates to a method for preparing 10-undecenoic acid and heptanal through the castor oil in the process. The method comprises the following steps: ester interchange is performed on the castor oil and methyl alcohol to generate ricinic acid methyl ester; catalytic cracking is performed on the ricinic acid methyl ester to generate10-undecenoic acid methyl ester and heptanal; pressure-reduction rectification separation is performed on the 10-undecenoic acid methyl ester and heptana; saponification and acidification are performed on the 10-undecenoic acid methyl ester and heptana, so that 10-undecylenic acid is obtained; the ricinic acid methyl ester is mixed with water (or water vapor) according to the mass ratio of 1:(0.5-2), the mixture is preheated to 200-400 DEG C, and then is loaded into a cracking still filled with a catalyst, and cracking is performed at the temperature of 400-500 DEG C, so that the 10-undecenoic acid and heptanal are generated. According to the invention, due to catalytic action, the cracking temperature is reduced greatly, so that side reactions such as polymerization and isomerization of the double bond, the secondary cracking of a product and coking are reduced, and the yield of the 10-undecenoic acid and heptanal is improved greatly.
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Paragraph 0035
(2017/03/08)
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- Configurational Assignment of ‘Cryptochiral’ 10-Hydroxystearic Acid Through an Asymmetric Catalytic Synthesis
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An asymmetric catalytic total synthesis of (S)-10-hydroxystearic acid (1) for comparison of its absolute configuration to that of samples obtained by fermentative hydration of oleic acid is reported. The synthesis involves two catalytic key-steps, namely Ru-catalyzed anti-Markovnikov hydration of 9-decynoic acid (7) to 10-oxodecanoic acid (5), followed by titanium-mediated asymmetric catalytic addition of dioctylzinc (25) to 5 in presence of the chiral ligand N,N’-((1R,2R)-cyclohexane-1,2-diyl)bis(1,1,1-trifluoromethanesulfonamide) (6). The synthesis is short and efficient and avoids use of protecting groups. Ozonolysis of 10-undecynoic acid (9) to 5 provides an alternative entry point into the synthetic route. The double dehydrobromination of (ω,ω-1)-dibromoalkanoic acids to ω-alkynoic acids under a variety of conditions was investigated with 10,11-dibromoundecanoic acid (11) as model substrate and using qNMR to quantify all reaction products. The synthetic approaches presented here have the potential to be generalized to the asymmetric catalytic synthesis of a variety of n-hydroxy-fatty acids.
- Brunner, Andreas,Hintermann, Lukas
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p. 928 - 943
(2016/12/09)
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- Enzymatic Oxidative Tandem Decarboxylation of Dioic Acids to Terminal Dienes
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The biocatalytic oxidative tandem decarboxylation of C7–C18dicarboxylic acids to terminal C5–C16dienes was catalyzed by the P450 monooxygenase OleT with conversions up to 29 % for 1,11-dodecadiene (0.49 g L–1). The sequential nature of the cascade was proven by the fact that decarboxylation of intermediate C6–C11ω-alkenoic acids and heptanedioic acid exclusively gave nonconjugated 1,4-pentadiene; scale-up allowed the isolation of 1,15-hexadecadiene and 1,11-dodecadiene; the system represents a short and green route to terminal dienes from renewable dicarboxylic acids.
- Dennig, Alexander,Kurakin, Sara,Kuhn, Miriam,Dordic, Andela,Hall, Mélanie,Faber, Kurt
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supporting information
p. 3473 - 3477
(2016/07/29)
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- Copper-catalyzed selective semihydrogenation of terminal alkynes with hypophosphorous acid
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A novel copper-catalyzed selective semihydrogenation of terminal alkynes using hypophosphorous acid as hydrogen donor took place efficiently to afford the corresponding alkenes in high yields. A broad range of substituted terminal aromatic and aliphatic alkenes, including terminal dienes and enynes bearing internal triple bonds, can be efficiently synthesized by this reaction.
- Cao, Huanyang,Chen, Tieqiao,Zhou, Yongbo,Han, Daoqing,Yin, Shuang-Feng,Han, Li-Biao
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p. 765 - 769
(2014/04/03)
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- Magtrieve: A convenient catalyst for the oxidation of alcohols
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We find that Magtrieve (CrO2) catalyzes the oxidation of a wide variety of alcohols with periodic acid as the terminal oxidant. Mild conditions, short reaction times, and facile aqueous work-up make this a most attractive method. Olefins are not oxidized under these conditions; thus alcohols react selectively in the presence of alkenes. Conditions have been optimized with respect to catalyst loading, solvent, and co-oxidant; and the scope of the reaction includes primary and secondary benzylic, allylic, and aliphatic alcohols.
- Few, Chip S.,Williams, Kathryn R.,Wagener, Kenneth B.
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supporting information
p. 4452 - 4454
(2014/08/05)
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- Aerobic oxidation of aldehydes by visible light photocatalysis
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An efficient and environmentally benign method for the oxidation of aldehydes to carboxylic acids has been developed. Singlet oxygen, generated by visible light in the presence of a Ru or Ir photocatalyst, reacted with aldehydes to give the corresponding carboxylic acids in excellent yields. The reaction is highly chemo-selective, in which only an aldehyde moiety is reactive even in the presence of other photo-oxidation active sites. This method is an example of an ideal green chemical reaction in the sense that molecular oxygen and visible light are key sources for the transformation.
- Iqbal, Naeem,Choi, Sungkyu,You, Youngmin,Cho, Eun Jin
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supporting information
p. 6222 - 6225
(2013/10/22)
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- Rapid-throughput competitive colorimetric assay based on monosaccharide-capped gold nanoparticles for detecting lectin-protein interactions
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Identification of protein binding partners is one of key challenges in proteomics. A rapid-throughput competitive colorimetric assay is presented that uses gold nanoparticles capped by sugars such as mannopyranoside (Man-GNPs), N-acetylglucosamine (GlcNAc-GNPs), glucose (Glc-GNPs), or N-acetylgalactosamine (GalNAc-GNPs). The assay expediently detects protein- protein interactions in solution, particularly protein-lectin interactions. The competitive assays were conducted in microtiter plates; ten proteins (two glycoproteins and eight lectins) and three sugar-binding lectins (concanavalin A (ConA), wheat germ agglutinin (WGA), and Ricinus communis agglutinin (RCA120)) were combinatorially arranged in a 30-well plate, and constant concentrations of the monosaccharide-capped GNPs (sugar-GNPs) were added to each well. If interactions occurred between the proteins, the sugar-GNPs retained their burgundy color. If no interactions occurred between the proteins, the sugar-GNPs were agglomerated by the corresponding binding lectin, thus producing a blue color. Several new binding pairs were identified for the first time by using this assay, and the binding constants and stoichiometric ratios were determined on the basis of the wavelength shifts. The results were further verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and fluorescence resonance energy transfer (FRET) spectroscopy. The assay is very sensitive, requiring only nanomolar protein concentrations.
- Tsai, Charng-Sheng,Chen, Chao-Tsen
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p. 314 - 322
(2013/01/13)
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- Synthesis, rhodium complexes and catalytic applications of a new water-soluble triphenylphosphane-modified β-cyclodextrin
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A new triphenylphosphane based on a β-cyclodextrin skeleton (PM-β-CD-OTPP) was synthesized. This ligand can be dispersed in water by using the nanoprecipitation method. Transmission electron microscopy and NMR spectroscopy showed that PM-β-CD-OTPP is aggregated in water and forms a stable dispersion. Its aqueous solubility can be dramatically increased in the presence of selected water-soluble guests by formation of inclusion complexes. Associated to a rhodium precursor, PM-β-CD-OTPP is able to generate soluble rhodium species in water. In addition, NMR experiments showed that the cyclodextrin cavity remains accessible for a guest even when PM-β-CD-OTPP is coordinated to rhodium. Finally, this ligand was efficient for rhodium-catalyzed hydrogenation and hydroformylation performed in aqueous medium.
- Legrand, Francois-Xavier,Six, Natacha,Slomianny, Christian,Bricout, Herve,Tilloy, Sebastien,Monflier, Eric
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supporting information; experimental part
p. 1325 - 1334
(2011/07/09)
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- Chemical synthesis and biological evaluation of second-generation palmerolide a analogues
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In this communication, second-generation analogues of palmerolide A, a recently reported cytotoxic agent against melanoma cancer cells, were rationally designed, synthesized, and biologically evaluated. Structural variations of the enamide side chain and the C1-C8 segment of palmerolide A revealed a narrow structure-activity relationship window of the newly synthesized compounds. In addition, mechanistic and pharmacological studies were performed to assess the therapeutic potential of palmerolide A. Synthesis and biological evaluation of second-generation palmerolide A analogues are reported. This study focused on further modification of the enamide side chain, and the C1-C8 carbon backbone of palmerolide A. Structure-activity relationship, mechanistic, and pharmacological investigations of the palmerolide compounds pave the foundation for the ensuing in vivo studies.
- Ravu, Vengala Rao,Leung, Gulice Y. C.,Lim, Chek Shik,Ng, Sin Yee,Sum, Rong Ji,Chen, David Y.-K.
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supporting information; experimental part
p. 463 - 468
(2011/04/17)
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- Cosmetic use of microorganism(s) for the treatment of scalp disorders
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The present invention relates to a use of an effective amount of at least one probiotic microorganism and/or a fraction thereof and/or a metabolite thereof for preventing and/or treating dandruff disorders of the scalp, as well as a cosmetic process for preventing and/or treating a dandruff condition including the administration a first cosmetic active agent and of at least a second cosmetic active agent, topically, the said first and second cosmetic active agents being formulated in separate compositions, the first cosmetic active agent being chosen from probiotic microorganisms, and mixtures thereof, and the second cosmetic active agent being chosen from antidandruff active agents.
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- METHOD FOR THE SYNTHESIS OF DIACIDS OR DIESTERS FROM NATURAL FATTY ACIDS AND/OR ESTERS
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The invention relates to a process for the synthesis of diacids or diesters of general formula ROOC—(CH2)x—COOR, in which n is an integer between 5 and 14, R is either H or an alkyl radical of 1 to 4 carbon atoms, from natural long-chain monounsaturated fatty acids or esters including at least 10 adjacent carbon atoms per molecule of the general formula CH3—(CH2)n—CHR1—CH2—CH═CH—(CH2)p—COOR, in which R is H or an alkyl radical with 1 to 4 carbon atoms, R1 is either H or OH, and n and p, which are equal or different and are indices between 2 and 11. The method comprises: during a first step, converting the natural fatty acid or ester by pyrolysis or by ethenolysis, into a ω-monounsaturated fatty acid or ester of the general formula CH2═CH—(CH2)m—COOR, in which m is equal to p or p+1, depending on the nature of the processed fatty acid/ester and the conversion used; during a second step, submitting the product thus obtained to a metathesis or homometathesis reaction for obtaining a compound of the general formula ROOC—(CH2)m—CH═CH—(CH2)m—COOR, or cross-metathesis with a compound of formula R2OOC—(CH2)r—CH═CH—R3, in which R2 is either H or an alkyl radical front with 1 to 4 carbon atoms, r is either 0 or 1 or 2 and R3 is H, CH3 or COOR2, thus defining a cyclic or molecule or not, in order to obtain an unsaturated compound of the general formula ROOC—(CH2)m—CH═CH—(CH2)r—COOR2, and during a third step, converting the unsaturated compound into a saturated compound by hydrogenation of the double bond.
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Page/Page column 6
(2010/12/29)
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- A new and highly effective organometallic approach to 1,2-dehalogenations and related reactions
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We investigated the reductive elimination of several functionalized and non-functionalized vic-dibromides with 1,2-diphenyl-, 1,1,2,2-tetraphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodioethane. The reaction, involving some of the less expensive organic and inorganic reagents, proceeds under mild conditions, and is tolerant of a variety of functional groups. Extension of this procedure to similar 1,2-disubstituted compounds was also investigated. Reductive eliminations run on stereochemical probe compounds strongly suggest that this reaction proceeds via a "single electron" reductive elimination reaction pathway.
- Azzena, Ugo,Pittalis, Mario,Dettori, Giovanna,Pisano, Luisa,Azara, Emanuela
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p. 3892 - 3900
(2008/03/12)
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- Method for producing carboxylic acid
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An aldehyde-containing oily solution and an aqueous hydrogen peroxide solution are reacted in the presence of a catalyst comprising a polymer compound having a sulfonic acid group in a side chain thereof in a heterogeneous solution system. According to such a reaction process, carboxylic acid can be efficiently produced under mild conditions having very little influence and toxicity on the environment and a human body, with simple operations, without requiring the operation for removing a solvent after the completion of the reaction.
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Page/Page column 4
(2008/06/13)
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- Oxidation of alcohols with catalytic amounts of IBX
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Herein we present a catalytic IBX-based method for the oxidation of alcohols. Using this system a variety of benzylic alcohols were transformed to aldehydes in good yields whereas secondary alcohols were easily converted to ketones. Primary aliphatic alcohols were oxidised to the corresponding carboxylic acids. 2-lodobenzoic acid can also be used instead of IBX. Georg Thieme Verlag Stuttgart.
- Schulze, Agnes,Giannis, Athanassios
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p. 257 - 260
(2007/10/03)
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- Reducing properties of 1,2-diaryl-1,2-disodiumethanes
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1,2-Diphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodiumethane efficiently dehalogenate vic-dibromoderivatives, affording the corresponding alkenes. The reaction proceeds rapidly, under mild conditions and is tolerant of a variety of functional groups (alcohol, carboxylic acid, ester and amide). This procedure was successfully extended to similar vic-disubstituted compounds.
- Azzena, Ugo,Pittalis, Mario,Dettori, Giovanna,Madeddu, Simona,Azara, Emanuela
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p. 1055 - 1058
(2007/10/03)
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- Gold nanoparticle-based competitive colorimetric assay for detection of protein-protein interactions
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A gold nanoparticle-based competitive colorimetric assay uses the ensemble of Concanavalin (ConA) and mannopyranoside-encapsulated gold nanoparticles (Man-GNPs) to identify the binding partners for ConA and the binding constants are determined based on the wavelength shifts. The Royal Society of Chemistry 2005.
- Tsai, Charng-Sheng,Yu, Ting-Bin,Chen, Chao-Tsen
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p. 4273 - 4275
(2007/10/03)
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- Product selectivity in the electroreduction of thioesters
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The electroreduction of differently substituted aromatic and aliphatic thioesters (RCOSR′) led to regioselective reactions depending on the nature of the substituents. Thus, the cleavage between the carbonyl group and the SR′ group afforded α-diketones an
- We?wer,Olivero,Du?ach
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p. 1709 - 1714
(2007/10/03)
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- INHIBITORS OF FUNGAL INVASION
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This invention relates to various anti-fungall agents including agents that are inhibitors of fungal invasion.
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Drawing sheet 79
(2010/02/09)
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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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- Crosslinking of cellulose by olefin metathesis
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New crosslinked microcrystalline cellulose plastic films were made by olefin metathesis. Cellulose was first acylated under microwave irradiation by 10-undecenoyl chloride in lithium chloride/N,N-dimethylacetamide homogeneous solution to yield unsaturated fatty acid cellulose esters with a degree of substitution (DS) varying from 1 to 2. After studying the variation of cellulose DS vs. microwave irradiation time, the unsaturated fatty acid cellulose esters were subjected to olefin metathesis using Grubbs's catalyst. Crosslinking ratio T (0% 1H NMR spectroscopic data.
- Joly,Granet,Krausz
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- Organofunctional cocyclic siloxanes
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New compositions of matter are organofunctional cocyclic siloxanes of the formula STR1 where R1 to R3 are alkyl groups of 1-6 carbon atoms; a and b have a value of 1-10; and R4 is an aminoalkyl group or a carboxyalkyl group. Some representative R4 groups are --CH2 CH2 CH2 NH2, --CH2 CH2 CH2 NHCH2 CH2 NH2, --CH2 CH(CH3)CH2 NHCH2 CH2 NH2, and --(CH2)10 COOH.
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- Hydrogen peroxide oxidation of aldehydes to carboxylic acids: An organic solvent-, halide- and metal-free procedure
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Aqueous hydrogen peroxide oxidizes aldehydes to carboxylic acids under aqueous/organic biphasic conditions without affecting olefinic or alcoholic functions (C) 2000 Elsevier Science Ltd.
- Sato, Kazuhiko,Hyodo, Mamoru,Takagi, Junko,Aoki, Masao,Noyori, Ryoji
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p. 1439 - 1442
(2007/10/03)
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- Arylmethyl esters as protecting groups for carboxylic, carbonic and carbamic acids: Deprotection via homogeneous palladium-catalyzed hydrogenolysis
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4-Quinolylmethyl (4-QUI) esters of carboxylic acids and 1-naphthylmethyl (1-NAP) esters of carbonic and carbamic acids are reduced by palladium-catalyzed hydrogenolysis by formate anion. The reaction conditions are compatible with the presence of a benzyl ester and of an alkene double bond.
- Boutros, Andre,Legros, Jean-Yves,Fiaud, Jean-Claude
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p. 7329 - 7332
(2007/10/03)
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- Reductive cleavage of 2,2,2-trichloroethyl esters with sodium telluride
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Carboxylic acids are regenerated from their 2,2,2,-trichloroethyl esters by treatment with sodium telluride in dimethylformamide in smooth conditions and with good yields. The reaction conditions are compatible with other functional and protective groups such as methyl ester, acetate or tert- butyldimethylsilyl ethers.
- Blay, Gonzalo,Cardona, Luz,Garcia, Begona,Garcia, Cristina L.,Pedro, Jose R.
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p. 1405 - 1414
(2007/10/03)
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- Palladium-Catalyzed Carbonylative Cross-Coupling Reaction of Iodoalkaneswith 9-Alkyl-9-BBN Derivatives. A Direct and Selective Synthesis of Ketones
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The synthesis of unsymmetrical ketones by means of the palladium-catalyzed carbonylative cross-coupling reaction of 9-alkyl-9-BBN derivatives with iodoalkanes under a carbon monoxide atmosphere is described.
- Ishiyama, Tatsuo,Miyaura, Norio,Suzuki, Akira
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p. 6923 - 6926
(2007/10/02)
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- Synthesis of ω-Unsaturated Acids
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A short, high-yield method for the synthesis of ω-unsaturated acids have been developed that precludes any double-bond migration or hydrogenation.Key is the coupling reaction between Grignards of ω-unsaturated alkyl halides and the bromomagnesium salt of ω-bromo fatty acids.The reaction has been successfully extended to ω-bromo nitriles.The use of ω-chloro acids or α-bromo acids gives lower yields of heterocoupling products and substantial homocoupling.A catalyst study shows Li2CuCl4 to yield the most heterocoupling of several catalysts tried for the chloro acids, and Ni(II) or Cu(I) are best for the α-bromo acids.
- Mirviss, Stanley B.
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p. 1948 - 1951
(2007/10/02)
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- TRIMETHYLSILYL ESTERS: TEMPORARY PROTECTION OF CARBOXYLIC ACIDS DURING HYDROBORATION REACTIONS
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Carboxylic acid are readily protected during hydroboration reactions by converting them to the corresponding trimethylsilyl esters.
- Kabalka, George W.,Bierer, Donald E.
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p. 2783 - 2788
(2007/10/02)
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- A Facile Method for the Oxidation of Aldehydes to Carboxylic Acids via Acetal-type Diperoxides
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In the presence of a catalytic amount of trityl perchlorate, aldehydes smoothly react with t-butyl trimethylsilyl peroxide to give the acetal-type diperoxides in good yields.Treatment of these diperoxides with piperidine at 90 degC or the aqueous solution of CuSO4 and L-ascorbic acid at room temperature gave the corresponding carboxylic acids in good yields.
- Mukaiyama, Teruaki,Miyoshi, Norikazu,Kato, Jun-ichi,Ohshima, Masahiro
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p. 1385 - 1388
(2007/10/02)
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- A ONE STEP SYNTHESIS OF ω-HYDROXYACETYLENIC CARBOXYLIC ACIDS
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A convenient chemioselective method to prepare ω-hydroxyacetylenic carboxylic acids from unprotected ω-alkyn-1 ols and ω-bromo acids is described.
- Cossy, J.,Pete, J. P.
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p. 573 - 574
(2007/10/02)
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- SYNTHESIS OF SELENOACETALS
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This paper reports our results concerning the syntheses of various bis(alkylseleno)alkanes and some of their arylseleno analogues by different methods.The scope and limitation of each of them are presented.
- Clarembeau, M.,Cravador, A.,Dumont, W.,Hevesi, L,Krief, A.,et al.
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p. 4793 - 4812
(2007/10/02)
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- Anodic Oxidation of Organoboranes
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Organoboranes are converted into more easily oxidizable borates by reaction with nucleophiles and the alkyl groups are dimerized by anodic oxidation.The oxidation potentials (Ep) of the borates depend strongly on the nature of the complexing nucleophile, for instance Ep = +0.37 V (vs.SCE) with OH- or +1.65 V with tetrahydrofuran.The dimer yields are optimized with trioctylborane (5) by variation of the electrode material and the elctrolyte.At the platinum anode in sodium hydroxide-methanol/tetrahydrofuran yields of 80percent are obtained for acyclic alkyl groups, and lo wer ones for cycloalkyl groups.They exceed those obtained by the Kolbe electrolysis or the oxidation with neutral hydrogen peroxide and they are comparable to those of the AgNO3 oxidation. - The selective preparation of unsymmetrical products from borates with different alkyl groups is not possible, the dimerization proceeds likely via free radicals that couple statistically.Good yields of unsymmetrical coupling products are achieved, when one olefin is used in excess.With choro-, ethoxy-, acetoxy-, and aryl-substituted alkyl groups the dimers are obtained in 21 - 66percent yield, with bromide the yield are lower and with nitriles the dimerization fails.
- Schlegel, Guenter,Schaefer, Hans J.
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p. 1400 - 1423
(2007/10/02)
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- CHEMOSELECTIVITY IN MOLYBDENUM CATALYZED ALCOHOL AND ALDEHYDE OXIDATIONS
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Hydrogen peroxide in the presence of (NH4)6Mo7O24*4H2O and potassium carbonate is a chemoselective method to oxidize secondary alcohols to ketones and to oxidize aldehydes to acids, the latter also accelerated by cerium chloride.
- Trost, Barry M.,Masuyama, Yoshiro
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p. 173 - 176
(2007/10/02)
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- Pd(0)-Catalyzed Electroreductive Cleavage of Allylic Acetates1
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Pd(0)-catalyzed electroreductive cleavage of allylic acetates yielding alkenes and/or allyltrimethylsilanes is described.Deprotection of allyl esters can be performed in the same electrolysis system.
- Torii, Sigeru,Tanaka, Hideo,Katoh, Tetsuo,Morisaki, Kazuo
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p. 3207 - 3208
(2007/10/02)
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- Selective catalytic oxidation of unsaturated alcohols to carbonyl compounds
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Primary and secondary unsaturated alcohols are converted to their corresponding aldehydes and/or carboxylic acids and ketones respectively with alkali metal (per) halate, preferably sodium periodate, in the presence of ruthenium catalyst. The process is particularly useful in the oxidation of chrysanthemyl alcohol. Any unconverted intermediate aldehyde formed may be converted to the acid by recycling or by a separate oxidation step.
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- A NEW OXIDATION OF ALDEHYDES TO CARBOXYLIC ACIDS
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2-Hydroperoxyhexafluoro-2-propanol (HPHI) is a selective catalytic and stoichiometric reagent for the oxidation of aldehydes to acids under mildly basic conditions.
- Ganem, Bruce,Heggs, Richard P.,Biloski, Alan J.,Schwartz, Daniel R.
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p. 685 - 688
(2007/10/02)
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