- Palladium(II)-catalyzed selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids with hydrogen peroxide
-
Palladium(II)-catalyzed chemoselective oxidation of αβ- unsaturated aldehydes with hydrogen peroxide to give Oα,β-unsaturated carboxylic acids was performed. Cinnamaldehyde was effectively catalyzed by palladium(II) trifluoroacetate to generate cinnamic acid in 92% yield under organic solvent-free conditions. The reaction appears to be applicable to various α,β-unsaturated aldehydes. Copyright
- Kon, Yoshihiro,Imao, Daisuke,Nakashima, Takuya,Sato, Kazuhiko
-
-
Read Online
- Iron-catalyzed selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids by molecular oxygen
-
Selective oxidation of α,β-unsaturated aldehydes to α,β-unsaturated carboxylic acids was performed using O2 as the oxidant in the presence of a simple iron catalyst. The addition of an alkali metal carboxylate as a cocatalyst enhanced the selectivity for the desired product. Redox tuning of the iron catalyst via association with the alkali metal led to a controlled radical generation during the catalytic O2 oxidation.
- Tanaka, Shinji,Kon, Yoshihiro,Uesaka, Yumiko,Morioka, Ryo,Tamura, Masanori,Sato, Kazuhiko
-
-
Read Online
- Copper(II)-coordinated organic nanotube: A novel heterogeneous catalyst for various oxidation reactions
-
Copper(II)-coordinated organic nanotube can function as a heterogeneous catalyst for oxidation of a variety of organic compounds in the presence of hydrogen peroxide and tert-butyl hydroperoxide. The morphology of this catalyst remained same before and after the oxidation reactions. The catalyst can be reused for several times. In the presence of hydrogen peroxide, Copper(II)-coordinated organic nanotube formed a stable brown color peroxo bridge intermediate. But such intermediate did not form with tert-butyl hydroperoxide.
- Chattopadhyay, Tanmay,Kogiso, Masaki,Asakawa, Masumi,Shimizu, Toshimi,Aoyagi, Masaru
-
-
Read Online
- Unexpected AChE inhibitory activity of (2E)α,β-unsaturated fatty acids
-
A small library of (E) α,β-unsaturated fatty acids was prepared, and 20 different saturated and mono-unsaturated fatty acids differing in chain length were subjected to Ellman's assays to determine their ability to act as inhibitors for AChE or BChE. While the compounds were only very weak inhibitors of BChE, seven molecules were inhibitors of AChE holding IC50 = 4.3–12.8 M with three of them as significant inhibitors of this enzyme. The results have shown trans 2-mono-unsaturated fatty acids are better inhibitors for AChE than their saturated analogs. Furthermore, the screening results indicate that the chain length is crucial for obtaining an inhibitory efficacy. The best results were obtained for (2E) eicosenoic acid (14) showing inhibition constants Ki = 1.51 ± 0.09 M and Ki′ = 7.15 ± 0.55 M. All tested compounds were mixed-type inhibitors with a dominating competitive part. Molecular modelling calculations indicate a different binding mode of active/inactive compounds for the enzymes AChE and BChE.
- Loesche, Anne,Wiemann, Jana,Al Halabi, Zayan,Karasch, Julia,Sippl, Wolfgang,Csuk, René
-
-
Read Online
- Selective two-phase-hydrogenation of sorbic acid with novel water soluble ruthenium complexes
-
Neutral and cationic water soluble Cp*-ruthenium-complexes of the type [Cp*Ru(CO)Cl(PR3)] and [Cp*Ru(CO)(PR3)]CF3SO3 (R=CH2OH, (CH2)3OH, Ph-m-SO3Na) have been synthesized for the first time and have been used as catalysts in two-phase-hydrogenations. The neutral complexes have been fully characterized. But the cationic complexes which have not been isolated are effective catalysts for the selective hydrogenation of sorbic acid in water/n-heptane leading to the formation of cis-3-hexenoic acid and trans-3-hexenoic acid.
- Driessen-Hoelscher, Birgit,Heinen, Joerg
-
-
Read Online
- Synthesis of piperazine derivatives and biological evaluation of its inhibitory activities on vascular smooth muscle cell proliferation
-
A series of new N-substituted benzyl piperazine derivatives were synthesized using the appropriate synthetic route. The new compounds were characterized by IR, 1H NMR, MS and elemental analysis. All the compounds were screened for their inhibitory activities on vascular smooth muscle cell proliferation. Some of the compounds demonstrated moderate to good inhibition of vascular smooth muscle cell proliferation. The compounds (2h, 6h) were approximately equivalent in activity to heparin as a potent inhibitor. The possible structure-activity relationship of the inhibitory activity of all compounds was also discussed.
- Han, Sheng Hua,Chen, Jian Xin,Liu, Hong Yan,Zhang, Hai Rong,Ma, Peng Fei
-
-
Read Online
- Carboxy-telechelic polyolefins by ROMP using maleic acid as a chain transfer agent
-
The use of unprotected maleic acid (MA) as a chain transfer agent (CTA) during ring-opening metathesis polymerization (ROMP) of cis-cyclooctene (COE) to provide carboxy-telechelic PCOE with an average degree of polymerization (N) was described. Four sampl
- Pitet, Louis M.,Hillmyer, Marc A.
-
-
Read Online
- Palladium(II) catalyzed novel rearrangement of 1-allyloxy-1-siloxycyclopropanes
-
Pd(II) salts catalyze the rearrangement of 1-allyloxy-1-siloxycyclopropanes to provide a mixture of Δ2-, Δ3- and Δ4-hexenonic acids. This rearrangement proceeds via a double bond isomerization followed by a ring opening of
- Yasui, Kengo,Fugami, Keigo,Tanaka, Shuji,Tamaru, Yoshinao,Ii, Atsuhiko,Yoshida, Zen-Ichi,Saidi, Mohamad R.
-
-
Read Online
- Ligand-controlled divergent dehydrogenative reactions of carboxylic acids via C–H activation
-
Dehydrogenative transformations of alkyl chains to alkenes through methylene carbon-hydrogen (C–H) activation remain a substantial challenge. We report two classes of pyridine-pyridone ligands that enable divergent dehydrogenation reactions through palladium-catalyzed b-methylene C–H activation of carboxylic acids, leading to the direct syntheses of a,b-unsaturated carboxylic acids or g-alkylidene butenolides. The directed nature of this pair of reactions allows chemoselective dehydrogenation of carboxylic acids in the presence of other enolizable functionalities such as ketones, providing chemoselectivity that is not possible by means of existing carbonyl desaturation protocols. Product inhibition is overcome through ligand-promoted preferential activation of C(sp3)–H bonds rather than C(sp2)–H bonds or a sequence of dehydrogenation and vinyl C–H alkynylation. The dehydrogenation reaction is compatible with molecular oxygen as the terminal oxidant.
- Wang, Zhen,Hu, Liang,Chekshin, Nikita,Zhuang, Zhe,Qian, Shaoqun,Qiao, Jennifer X.,Yu, Jin-Quan
-
p. 1281 - 1285
(2021/12/10)
-
- In vitro studies of maleidride-forming enzymes
-
In vitro assays of enzymes involved in the biosynthesis of maleidrides from polyketides in fungi were performed. The results show that the enzymes are closely related to primary metabolism enzymes of the citric acid cycle in terms of stereochemical preferences, but with an expanded substrate selectivity. A key citrate synthase can react both saturated and unsaturated acyl CoA substrates to give solely anti substituted citrates. This undergoes anti-dehydration to afford an unsaturated precursor which is cyclised in vitro by ketosteroid-isomerase-like enzymes to give byssochlamic acid. This journal is
- Yin, Sen,Friedrich, Steffen,Hrupins, Vjaceslavs,Cox, Russell J.
-
p. 14922 - 14931
(2021/05/19)
-
- MANUFACTURING METHOD OF α,β-UNSATURATED CARBOXYLIC ACID
-
PROBLEM TO BE SOLVED: To provide a manufacturing method which can get α,β-unsaturated carboxylic acid at a high yield by liquid phase oxidation of α,β-unsaturated aldehyde by oxygen or air with a handy metal catalyst under a mild reaction condition. SOLUTION: Preferably under a presence of organic solvent, α,β-unsaturated carboxylic acid is manufactured by oxidation of α,β-unsaturated aldehydes and oxygen or air under a presence of an iron salt catalyst and a catalyst of alkali metal salt of carboxylic acid. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
- -
-
Paragraph 0050-0052
(2018/10/16)
-
- Characterization of FabG and FabI of the Streptomyces coelicolor dissociated fatty acid synthase
-
Streptomyces coelicolor produces fatty acids for both primary metabolism and for biosynthesis of the secondary metabolite undecylprodiginine. The first and last reductive steps during the chain elongation cycle of fatty acid biosynthesis are catalyzed by FabG and FabI. The S. coelicolor genome sequence has one fabI gene (SCO1814) and three likely fabG genes (SCO1815, SCO1345, and SCO1846). We report the expression, purification, and characterization of the corresponding gene products. Kinetic analyses revealed that all three FabGs and FabI are capable of utilizing both straight and branched-chain β-ketoacyl-NAC and enoyl-NAC substrates, respectively. Furthermore, only SCO1345 differentiates between ACPs from both biosynthetic pathways. The data presented provide the first experimental evidence that SCO1815, SCO1346, and SCO1814 have the catalytic capability to process intermediates in both fatty acid and undecylprodiginine biosynthesis.
- Singh, Renu,Reynolds, Kevin A.
-
p. 631 - 640
(2015/03/31)
-
- Selenium catalyzed oxidation of aldehydes: Green synthesis of carboxylic acids and esters
-
The stoichiometric use of hydrogen peroxide in the presence of a selenium-containing catalyst in water is here reported as a new ecofriendly protocol for the synthesis of variously functionalized carboxylic acids and esters. The method affords the desired products in good to excellent yields under very mild conditions starting directly from commercially available aldehydes. Using benzaldehyde as a prototype the gram scale synthesis of benzoic acid is described, in which the aqueous medium and the catalyst could be recycled at last five times while achieving an 87% overall yield.
- Sancineto, Luca,Tidei, Caterina,Bagnoli, Luana,Marini, Francesca,Lenardo, Eder J.,Santi, Claudio
-
p. 10496 - 10510
(2015/08/06)
-
- Oxidation of allylic and benzylic alcohols to aldehydes and carboxylic acids
-
An oxidation of allylic and benzylic alcohols to the corresponding carboxylic acids is effected by merging a Cu-catalyzed oxidation using O 2 as a terminal oxidant with a subsequent chlorite oxidation (Lindgren oxidation). The protocol was optimized to obtain pure products without chromatography or crystallization. Interception at the aldehyde stage allowed for Z/E-isomerization, thus rendering the oxidation stereoconvergent with respect to the configuration of the starting material.
- K?nning, Daniel,Olbrisch, Tobias,Sypaseuth, Fanni D.,Tzschucke, C. Christoph,Christmann, Mathias
-
supporting information
p. 5014 - 5016
(2014/05/06)
-
- Fe3O4 nanoparticles/ethyl acetoacetate system for the efficient catalytic oxidation of aldehydes to carboxylic acids
-
A new methodology for the oxidation of aldehydes promoted by commercially available Fe3O4 nanoparticles (Fe3O4 NPs) activated by ethyl acetoacetate was developed. The use of ethyl acetoacetate as additive was crucial to achieve high reactivities. All reactions were realized under solvent free conditions, using air or tBuOOH as oxidants. Finally, the separation and reuse of the magnetically recoverable nanoparticles make this methodology very practical, simple and economical.
- Villano, Rosaria,Acocella, Maria Rosaria,Scettri, Arrigo
-
p. 2442 - 2445
(2014/05/06)
-
- Control of the selectivity in multi-functional group molecules using supported gold-palladium nanoparticles
-
The oxidation of 2-hexen-1-ol and 1-hexen-3-ol with air has been studied using supported gold, palladium and gold-palladium catalysts. The main aim was to determine if either the alcohol or alkene functional group can be oxidised selectively. However, based on the reaction products observed (2-hexen-1-ol forms 2-hexene, hexanal, (E)-2-hexenal, (E)-3-hexen-1-ol, 4-hexen-1-ol and (E)-2-hexanoic acid. 1-Hexen-3-ol forms 1-hexene, 3-hexanone, 1-hexen-3-one and 3-hexenol), the main pathway in these reactions is isomerisation and, in addition, significant yields of the products are due to a disproportionation reaction. Controlling the selectivity in molecules with multiple function groups by manipulating the catalyst composition and reaction conditions can promote or hinder the various reaction pathways, thereby increasing the selectivity to the desired oxidation products.
- Alshammari, Hamed,Miedziak, Peter J.,Morgan, David J.,Knight, David W.,Hutchings, Graham J.
-
p. 1244 - 1254
(2013/06/26)
-
- Well-defined alkylpalladium complexes with pyridine-carboxylate ligands as catalysts for the aerobic oxidation of alcohols
-
Neophylpalladium complexes of the type [Pd(CH2CMe 2Ph)(N-O)(L)], where N-O is picolinate or a related bidentate, monoanionic ligand (6-methylpyridine-2-carboxylate, quinoline-2-carboxylate, 2-pyridylacetate or pyridine-2-sulfonate) and L is pyridine or a pyridine derivative, efficiently catalyze the oxidation of a range of aliphatic, benzylic and allylic alcohols with oxygen, without requiring any additives. A versatile method is described which allows the synthesis of the above-mentioned complexes with a minimum synthetic effort from readily available materials. Comparison of the rates of oxidation of 1-phenylethanol with different catalysts reveals the influence of the structure of the bidentate N-O chelate and the monodentate ligand L on the catalytic performance of these complexes. The Royal Society of Chemistry 2012.
- Melero, Cristobal,Shishilov, Oleg N.,Alvarez, Eleuterio,Palma, Pilar,Campora, Juan
-
p. 14087 - 14100
(2013/01/15)
-
- Elucidating the formation pathway of the off-flavor compound 6-propylbenzofuran-7-ol
-
In a previous work, we identified 6-propylbenzofuran-7-ol as an off-flavor compound formed from ascorbic acid and (E)-hex-2-enal in a test apple beverage. In this study, we elucidate the pathway by which 6-propylbenzofuran-7-ol formed. Isotope labeling studies revealed that the propyl group of 6-propylbenzofuran- 7-ol derives from (E)-hex-2-enal and that 6-propylbenzofuran-7-ol contains carbons 2-6 of ascorbic acid. Two compounds, namely, 2,3-dihydro-6- propylbenzofuran-3,7-diol and 3-(2-furoyl)hexanal, were identified as byproducts of a model reaction of ascorbic acid and (E)-hex-2-enal. Each of these compounds was dissolved in an aqueous solution of citric acid and stored at 60 °C for 1 week. After storage, 6-propylbenzofuran-7-ol was detected from a solution of 2,3-dihydro-6-propylbenzofuran-3,7-diol, but not from 3-(2-furoyl)hexanal. 6-Propylbenzofuran-7-ol was formed by isolating tricyclic hemiacetal lactone derived from the Michael addition of ascorbic acid to (E)-hex-2-enal, mixing the tricyclic hemiacetal lactone with the aqueous solution of citric acid, and applying heat. This confirmed that 6-propylbenzofuran-7-ol was formed via the Michael adduct.
- Sakamaki, Kensuke,Ishizaki, Susumu,Ohkubo, Yasutaka,Tateno, Yoshiyuki,Nakanishi, Akira,Fujita, Akira
-
p. 9967 - 9973,7
(2020/09/15)
-
- Engineering the nucleotide coenzyme specificity and sulfhydryl redox sensitivity of two stress-responsive aldehyde dehydrogenase isoenzymes of Arabidopsis thaliana
-
Lipid peroxidation is one of the consequences of environmental stress in plants and leads to the accumulation of highly toxic, reactive aldehydes. One of the processes to detoxify these aldehydes is their oxidation into carboxylic acids catalyzed by NAD(P)+-dependent ALDHs (aldehyde dehydrogenases). We investigated kinetic parameters of two Arabidopsis thaliana family 3 ALDHs, the cytosolic ALDH3H1 and the chloroplastic isoform ALDH3I1. Both enzymes had similar substrate specificity and oxidized saturated aliphatic aldehydes. Catalytic efficiencies improved with the increase of carbon chain length. Both enzymes were also able to oxidize α,β-unsaturated aldehydes, but not aromatic aldehydes. Activity of ALDH3H1 was NAD+-dependent, whereas ALDH3I1 was able to use NAD+ and NADP+. An unusual isoleucine residue within the coenzyme-binding cleft was responsible for the NAD +-dependence of ALDH3H1. Engineering the coenzyme-binding environment of ALDH3I1 elucidated the influence of the surrounding amino acids. Enzyme activities of both ALDHs were redox-sensitive. Inhibitionwas correlatedwith oxidation of both catalytic and noncatalytic cysteine residues in addition to homodimer formation. Dimerization and inactivation could be reversed by reducing agents. Mutant analysis showed that cysteine residues mediating homodimerization are located in the N-terminal region. Modelling of the protein structures revealed that the redox-sensitive cysteine residues are located at the surfaces of the subunits. The Authors Journal compilation
- Stiti, Naim,Adewale, Isaac O.,Petersen, Jan,Bartels, Dorothea,Kirch, Hans-Hubert
-
experimental part
p. 459 - 471
(2012/06/01)
-
- Method for regio- and stereoselective synthesis of (E)-Β,γ- unsaturated acids from aldehydes under solvent-free conditions
-
Synthesis of (E)-β,-γunsaturated acids from aldehydes with malonic acid has been explored under solvent-free conditions. The modified Knoevenagel condensation reaction with N-methyl morpholine (NMM) as catalyst exhibits highly β,-γ regioselectivity and exclusively E-stereoselectivity. A mechanism accounting for both regio- and stereoselectivity has been proposed and preliminarily studied. Copyright Taylor & Francis Group, LLC.
- Zhang, Shi-Jie,Hu, Wei-Xiao
-
experimental part
p. 3093 - 3100
(2010/12/19)
-
- Hydrogen-free homogeneous catalytic reduction of olefins in aqueous solutions
-
(Chemical Equation Presented) Herein we report a study involving the homogeneous catalytic reduction of unsaturated substrates in aqueous solutions or water-organic solvent mixtures. The reduction of olefins has been carried out in the presence of catalytic amounts of [Fe(CN)5NH3] 3- and excess of NH2OH, which under mild reaction conditions can be used to reduce carbon-carbon unsaturations without affecting carbonyl functionalities and aromatic rings. To explore the scope of the catalytic reduction, a wide variety of representative unsaturated substrates have been examined. The steric effects of the substituents on the carbon-carbon multiple bond as well as the regioselectivity and stereoselectivity of the catalyst have been studied. The deuterium kinetic isotope effect on the catalytic reduction of double bonds in olefins has been analyzed, and no significant kinetic isotope effect was found. Among the great advantages of this novel procedure for catalytic reduction are that hydrogen and high pressures are not needed, the catalyst is inexpensive and easily prepared, and water as well as water-organic solvent mixtures can be used as reaction media.
- Gaviglio, Carina,Doctorovich, Fabio
-
p. 5379 - 5384
(2008/12/20)
-
- Organocatalysis in conjugate amine additions. Synthesis of β-amino acid derivatives
-
Conjugate addition of O-protected hydroxylamines to pyrazole-derived enoates proceeds with high efficiency and enantioselectivity when chiral thioureas are used as activators. A wide variety of substrates undergo conjugate amine addition providing access to enantioenriched β-amino acid derivatives. Structural requirements for the optimal thiourea catalyst have been established, and the results suggest that it operates as a bifunctional catalyst. Copyright
- Sibi, Mukund P.,Itoh, Kennosuke
-
p. 8064 - 8065
(2008/02/09)
-
- Competitive formation of β-amino acids, propenoic, and ylidenemalonic acids by the Rodionov reaction from malonic acid, aldehydes, and ammonium acetate in alcoholic medium
-
The Rodionov reaction of 49 available aliphatic and aromatic aldehydes with malonic acid and ammonium acetate in alcoholic medium, resulting in formation of β-amino acids, propenoic, and ylidenemalonic acids, was studied. Certain regioselectivity regularities of the reaction were revealed. Among the variety of ketones studied, cyclohexanone is the only whose reaction yields a β-amino acid. Unusual dehydrofluorination of 6-chloro-2-fluorocinnamic acid under the Rodionov reaction was discovered. 2005 Pleiades Publishing, Inc.
- Lebedev,Lebedeva,Sheludyakov,Kovaleva,Ustinova,Kozhevnikov
-
p. 1113 - 1124
(2007/10/03)
-
- HIV integrase inhibitors
-
The present invention relates to the inhibition of HIV integrase, and to the treatment of AIDS or ARC by administering compounds of the following formula, or a tautomer of said compound, or a pharmaceutically acceptable salt, solvate or prodrug of said compound or of a tautomer thereof. wherein R1 is phenyl, wherein said phenyl is substituted from 1-3 times with R2, or R1 naphthyl, and wherein said naphthyl is optionally substituted from 1-3 times with R2; each R2 is independently selected from halo, C1-C3 alkyl, C1-C2 alkoxy, C1-C3 haloalkyl, and phenyl-(CH2)mOn—; m is 0 or 1; n is 0 or 1; and Z is methylene or —C(O)—, provided that when Z is —C(O)— said substituted phenyl is not ortho-chloro phenyl.
- -
-
-
- An ionic liquid as catalyst medium for stereoselective hydrogenations of sorbic acid with ruthenium complexes
-
The ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate (bmim PF6) (6) has been studied as catalyst medium for biphasic homogeneous hydrogenations of sorbic acid (1). As catalyst we used the Cp*-ruthenium-complex [Cp*Ru(η4-CH3-CH=CH-CH=CH-COOH) (CF3SO3)] which efficiently enables the stereoselective hydrogenation of sorbic acid leading to the formation of cis-3-hexenoic acid (3) in selectivities of up to 90% with turnover frequencies of up to 1100 h-1. Compared to other biphasic systems the hydrogenation in bmim PF6 proceeds with enhanced activity. The kinetics can be described with a Michaelis-Menten-equation, and the activation energy for the whole process was determined to be EA = 78 ± 5 kJ/mol. Wiley-VCH Verlag GmbH, 2000.
- Steines, Stephan,Wasserscheid, Peter,Driessen-Hoelscher, Birgit
-
p. 348 - 354
(2007/10/03)
-
- Thermodynamic and nuclear magnetic resonance study of the reactions of α- and β-cyclodextrin with acids, aliphatic amines, and cyclic alcohols
-
Titration calorimetry was used to determine equilibrium constants and standard molar enthalpy, Gibbs energy, and entropy changes for the reactions of a series of acids, amines, and cyclic alcohols with α- and β-cyclodextrin. The results have been examined in terms of structural features in the ligands such as the number of alkyl groups, the charge number, the presence of a double bond, branching, and the presence of methyl and methoxy groups. The values of thermodynamic quantities, in particular the standard molar Gibbs energy, correlate well with the structural features in the ligands. These structural correlations can be used for the estimation of thermodynamic quantities for related reactions. Enthalpy-entropy compensation is evident when the individual classes of substances studied herein are considered, but does not hold when these various classes of ligands are considered collectively. The NMR results indicate that the mode of accommodation of the acids and amines in the α-cyclodextrin cavity is very similar, but that the 1-methyl groups in 1-methylhexylamine and in 1-methylheptylamine and the N-methyl group in N-methylhexylamine lie outside the α-cyclodextrin cavity. This latter finding is consistent with the calorimetric results. Many of the thermodynamic and NMR results can be qualitatively understood in terms of van der Waals forces and hydrophobic effects.
- Rekharsky, Mikhail V.,Mayhew, Martin P.,Goldberg, Robert N.,Ross, Philip D.,Yamashoji, Yuko,Inoue, Yoshihisa
-
-
- Aerobic oxidation of alcohols to carbonyl compounds catalyzed by N-hydroxyphthalimide (NHPI) combined with Co(acac)3
-
Aerobic oxidation of various alcohols has been accomplished by using a new catalytic system. N-hydroxyphthalimide (NHPI) combined with Co(acac)3. The oxidation of alcohols by NHPI was found to be markedly enhanced by adding a slight amount of Co(acac)3 (0.05 equiv. to NHPI). Thus, secondary alcohols and vic-diols which are difficult to be oxidized by NHPI alone were smoothly oxidized with molecular oxygen (1 atm) to the corresponding carbonyl compounds under relatively mild conditions (65 ~ 75 °C).
- Iwahama, Takahiro,Sakaguchi, Satoshi,Nishiyama, Yutaka,Ishii, Yasutaka
-
p. 6923 - 6926
(2007/10/02)
-
- HETEROCYCLIC ACIDS
-
The invention concerns novel 1,3-dioxane alkenoic acid derivatives of the formula I wherein: n is the integer 1 or 2; Y is methyleneoxy, vinylene or ethylene; A1 is (1-6C)alkylene; R1 is a group of the formula R2A2 --, in which: R2 is phenyl unsubstituted
- -
-
-
- Straightforward synthesis of α,β-unsaturated acids and derivatives
-
A general C2 vinylic homologation from carbonyl compounds (aldehydes or ketones) which leads to various α,β-insaturated acids, esters and amides, is described.
- Tellier, Frederique,Sauvetre, Raymond
-
p. 5433 - 5436
(2007/10/02)
-
- Regioselective Hydrogenation of Conjugated Dienes Catalyzed by Hydridopentacyanocobaltate Anion using β-Cyclodextrin as the Phase-Transfer Agent and Lanthanide Halides as Promotors
-
β-Cyclodextrin is a useful phase-transfer agent for the hydrogenation of conjugated dienes to monoolefins catalyzed by the in situ generated hydridopentacyanocobaltate anion.This reaction, which usually proceeds by 1,2-addition to the diene, is promoted by cerium or lanthanum chloride.Polyethyleneglycol (PEG-400), with or without added lanthanide, can also used as the phase-transfer agent for the reduction process.
- Lee, Jong-Tae,Alper, Howard
-
p. 1854 - 1856
(2007/10/02)
-
- Straightforward Synthesis of 2-Alkenoic Acids from the Corresponding Saturated Aldehydes
-
2-Alkenoic acids may be prepared in good yields from saturated aldehydes via α-selenenylation with 4-(phenylseleno)morpholine formed in situ, followed by hydrogen peroxide oxidation.The actual oxidizing agent is benzeneperseleninic acid which is formed in the reaction medium.
- Outurquin, Francis,Paulmier, Claude
-
p. 690 - 691
(2007/10/02)
-
- STEREOSELECTIVE SYNTHESIS OF (E)-α,β-UNSATURATED ACIDS FROM C,O,O-TRI(TRIMETHYLSILYL) KETENE ACETAL AND ALDEHYDS
-
Aldehydes are converted into (E)-α,β-unsatured carboxylic acids by means of C,O,O-tri(trimethylsilyl) ketene acetal and a catalytic a mount of ZnBr2.
- Bellasoued, Moncef,Gaudemar, Marcel
-
p. 4551 - 4554
(2007/10/02)
-
- Process for the preparation of unsaturated aliphatic carboxylic acids
-
The invention relates to a process for the preparation of unsaturated aliphatic carboxylic acids by thermal cracking of the polymeric intermediate product ("polyester") which is formed in the catalytic reaction of aldehydes or ketones with ketene. The reaction mixture containing polyester is heated with water, and the polyester is then isolated and subjected to cracking. Or the polyester is first isolated and then heated with water and finally subjected to cracking. In both cases the temperature when the mixture is heated with water is the same as the boiling point, or is less than 40° C. below the boiling point, of the aqueous mixture.
- -
-
-
- Selective γ- Alkylation of Copper Enolates Derived from α,β-Unsaturated Acids: Factors Affecting Scope and Regio- and Stereoselectivity
-
Copper dienolates derived from α,β-unsaturated acids undergo alkylation at the γ-carbon with high regioselectivity.A systematic investigation has been made of several factors that affect the γ-alkylation process of the dienolate derived tiglic acid (1): alterations in the nature of the counterion, in the stoichiometry of cuprous ion, and in the nature of the electrophile.Compared to allylic electrophiles, nonallylic electrophiles react with copper dienolates sluggishly and with little selectivity for the γ-carbon; vinylic epoxides, however, are particularly goodalkylating agents.They undergo allylic transposition and react at the γ-carbon of the dienolate with high selectivity (70-90 percent), generating an allylic unit that forms part of a 1,5-diene skeleton oxygenated at both ends.Tiglic (1) and crotonic (3) acids react with vinylic epoxides to form a 1,5-diene with entirely E stereochemistry at the 2,3 double bond, while senecioic acid (2) forms a 1,5-diene with mostly Z stereochemistry at the 2,3 double bond.Geometry at the 6,7 double bond depends both on the α,β-unsaturated acid used and on the structure of the epoxide.With allylic electrophiles under direct (SN2) attack, stereochemical analysis showed that some isomerization occurs around the 6,7 double bond (derived from the electrophile).Addition of cuprous ion to the lithium dianion of 2-hexenoic acid (17) was found to enhance the regioselectivity of γ alkylation, but a subsequent Michael addition reaction limits the potential of γ alkylation in this system.
- Savu, Patricia M.,Katzenellenbogen, John A.
-
p. 239 - 250
(2007/10/02)
-
- Poly(styryl)bipyridine: Synthesis and formation of transition-metal complexes and some of their physical, chemical, and catalytic properties
-
Poly(styryl)bipyridine, 1, is produced from the reaction of lithiated polystyrene with bipyridine in tetrahydrofuran. Under our conditions, bipyridine becomes bound to 10-15% of the phenyl residues. The reaction of 1 with a variety of transition-metal salts can be carried out in a variety of swelling solvents and results in formation of polymer-bound bipyridine transition-metal complexes. The extent of metal incorporation depends on solvent, metal ion concentration, and the identity of the metal species. Zerovalent metal complexes such as&24C5;-Ph-bpy-M(CO)4 (M = Cr, Mo, W) are readily prepared from the reaction of 1 with the metal hexacarbonyl complexes. (Poly(styryl)bipyridyl)palladium acetate is an active catalyst for the hydrogenation of olefins at ambient pressure and temperature. It can also be used to catalyze the acetoxylation of benzene; however, the percent conversion in this case is rather low.
- Card, Roger J.,Neckers, Douglas C.
-
p. 2345 - 2349,2347,2349
(2007/10/05)
-
- Synergistic composition comprising PGF2α and PGE2
-
A synergistic composition comprising as active ingredients a PGF2α compound or its cyclodextrin clathrate thereof and a PGE2 compound or its cyclodextrin clathrate thereof, at a weight ratio of from about 1:0.33 to about 1:1.
- -
-
-