- Enantioselective extraction of fenvaleric acid enantiomers by two-phase (W/O) recognition chiral extraction
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To establish an extraction method for fenvaleric acid (FA) enantiomers using l-iso-butyl-l-tartaric esters and hydroxypropyl-β-cyclodextrin (HP-β-CD) as chiral selector, the distribution of FA enantiomers was examined in methanol aqueous solution containing HP-β-CD and 1,2-dichloroethane organic solution containing l-iso-butyl-l-tartaric esters. The influences of the concentration of l-iso-butyl-l-tartaric esters and HP-β-CD, organic diluent, pH, extraction temperature and the concentration of methanol aqueous solution on the partition coefficient (k) and separation factor (α) of FA were investigated. The experiment results showed that the complex formed by l-iso-butyl-l-tartaric esters with S-enantiomer is stabler than that with R-enantiomer. With the increase of the concentration of l-iso-butyl-l-tartaric ester, k and α increased; With the increase of the concentration of HP-β-CD, k increased firstly, and then decreased, but α increased all the while, k was the highest when the concentration of HP-β-CD was 4 mmol L-1. 1,2-dichloroethane organic diluent was better than the others. With the increase of pH, k and α decreased; with further increasing concentration of methanol aqueous solution, k and α decreased, k and α were the highest when the concentration of methanol aqueous solution was 10%. The extraction temperature had a great influence on k and α, too.
- Yi, Jian Min,Huang, Sai Jin,Jiang, Yu Ren,Tang, Ke Wen
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Read Online
- Enantioselective Hydrogenation of Tetrasubstituted α,β-Unsaturated Carboxylic Acids Enabled by Cobalt(II) Catalysis: Scope and Mechanistic Insights
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Chiral carboxylic acids are important compounds because of their prevalence in pharmaceuticals, natural products and agrochemicals. Asymmetric hydrogenation of α,β-unsaturated carboxylic acids has been widely recognized as one of the most efficient synthetic approaches to afford such compounds. Although related asymmetric hydrogenation of di- and trisubstituted unsaturated acids with noble metals is well established, asymmetric hydrogenation of challenging tetrasubstituted α,β-unsaturated carboxylic acids is rarely reported. We demonstrate enantioselective hydrogenation of cyclic and acyclic tetrasubstituted α,β-unsaturated carboxylic acids via cobalt(II) catalysis. This protocol showed broad substrate scope and gave chiral carboxylic acids in good yields with excellent enantiocontrol (up to 98 % yield and 99 % ee). Combined experimental and computational mechanistic studies support a CoII catalytic cycle involving migratory insertion and σ-bond metathesis processes. DFT calculations reveal that enantioselectivity may originate from the steric effect between the phenyl groups of the ligand and the substrate.
- Du, Xiaoyong,Xiao, Ye,Yang, Yuhong,Duan, Ya-Nan,Li, Fangfang,Hu, Qi,Chung, Lung Wa,Chen, Gen-Qiang,Zhang, Xumu
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supporting information
p. 11384 - 11390
(2021/04/09)
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- Manganese Catalyzed Hydrogenation of Enantiomerically Pure Esters
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A manganese-catalyzed hydrogenation of esters has been accomplished with TONs up to 1000, using cheap, environmentally benign, potassium carbonate and simple alcohols as activator and solvent, respectively. The weakly basic conditions lead to good functional group tolerance and enable the hydrogenation of enantiomerically enriched α-chiral esters with essentially no loss of stereochemical integrity.
- Widegren, Magnus B.,Clarke, Matthew L.
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p. 2654 - 2658
(2018/05/17)
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- Soluble and functional expression of a recombinant enantioselective amidase from Klebsiella oxytoca KCTC 1686 in Escherichia coli and its biochemical characterization
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A gene encoding an enantioselective amidase (KamH) was cloned from Klebsiella oxytoca KCTC 1686 and inserted into the EcoRI and HindIII sites of the vector pET-30a(+). When KamH with a peptide containing a His-tag and an enterokinase cleavage site was overexpressed in Escherichia coli, approximately half was found in the soluble fraction, but it lacked activity. After cleavage of the peptide by enterokinase, the enzyme activity was partly restored, reaching 420.2 ± 33.62 U/g dry cell weight (DCW). Another recombinant plasmid was constructed by inserting the KamH gene into the NdeI and EcoRI sites of pET-30a(+) to express KamH in its native form. The overexpressed amidase was found primarily in the soluble fraction and its maximum activity was 3613.4 ± 201.68 U/g DCW. This indicated that the peptide influenced not only soluble expression but also activity of KamH, perhaps by blocking the substrate-binding tunnel of KamH. Similar results were obtained with heterologously expressed amidases from Rhodococcus erythropolis MP50 and Agrobacterium tumefaciens d3. All of these amidases have an N-terminal α-helical domain. Therefore, amidases of this type may be functionally expressed in their native form. KamH hydrolyzed a range of aliphatic and aromatic amides and exhibited strict S-selectivity towards racemic amides.
- Guo, Fa-Mou,Wu, Jian-Ping,Yang, Li-Rong,Xu, Gang
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p. 1264 - 1271
(2015/07/08)
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- Screening of by-products of esfenvalerate in aqueous medium using SBSE probe desorption GC-IT-MS technique
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The pyrethroids, their metabolites and by-products have been recognized as toxic to environment and human health. Despite several studies about esfenvalerate toxicity and its detection in water and sediments, information about its degradation products is still scanty. In this work, esfenvalerate degradation products were obtained by chemical oxidation with hydrogen peroxide and their structure was elucidated using a procedure known as stir bar sorptive extraction (SBSE) probe desorption gas chromatography-ion trap mass spectrometry (GC-IT-MS) analysis. This procedure consists of the thermal desorption of analytes extracted from a SBSE stir bar introduced by a probe into a gas chromatograph (GC) coupled to an ion trap mass spectrometry (IT-MS) system. Based on IT-MS data, a degradation pathway of esfenvalerate is proposed with ten products of chemical oxidation of esfenvalerate that are fully identified. Among these compounds, 3-phenoxybenzoic acid and 3-phenoxybenzaldehyde were detected, reported as being environmental metabolites of some pyrethroids, with endocrine-disrupting activity.
- Colombo, Renata,Ferreira, Tanare C. R.,Yariwake, Janete H.,Lanza, Marcos R. V.
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p. 1831 - 1837
(2015/09/22)
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- The first synthetic agonists of FFA2: Discovery and SAR of phenylacetamides as allosteric modulators
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Free fatty acid receptor 2 (FFA2) is a G-protein coupled receptor for which only short-chain fatty acids (SCFAs) have been reported as endogenous ligands. We describe the discovery and optimization of phenylacetamides as allosteric agonists of FFA2. These novel ligands can suppress adipocyte lipolysis in vitro and reduce plasma FFA levels in vivo, suggesting that these allosteric modulators can serve as pharmacological tools for exploring the potential function of FFA2 in various disease conditions.
- Wang, Yingcai,Jiao, Xianyun,Kayser, Frank,Liu, Jiwen,Wang, Zhongyu,Wanska, Malgorzata,Greenberg, Joanne,Weiszmann, Jennifer,Ge, Hongfei,Tian, Hui,Wong, Simon,Schwandner, Ralf,Lee, Taeweon,Li, Yang
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scheme or table
p. 493 - 498
(2010/04/26)
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- Ru-catalyzed asymmetric hydrogenation of racemic aldehydes via dynamic kinetic resolution: Efficient synthesis of optically active primary alcohols
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A highly efficient asymmetric hydrogenation of racemic α-arylaldehydes via dynamic kinetic resolution has been developed by using [RuCl2(SDPs)(diamine)] complexes as catalysts, providing chiral primary alcohols in excellent enantioselectivities. Copyright
- Xie, Jian-Hua,Zhou, Zhang-Tao,Kong, Wei-Ling,Zhou, Qi-Lin
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p. 1868 - 1869
(2007/10/03)
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- Purification and characterization of a novel pyrethroid hydrolase from Aspergillus niger ZD11
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The pyrethroid pesticides residues on foods and environmental contamination are a public safety concern. Pretreatment with pyrethroid hydrolase has the potential to alleviate the conditions. For this purpose, a fungus capable of using pyrethroid pesticides as a sole carbon source was isolated from the soil and characterized as Aspergillus niger ZD11. A novel pyrethroid hydrolase from cell extract was purified 41.5-fold to apparent homogeneity with 12.6% overall recovery. It is a monomeric structure with a molecular mass of 56 kDa, a pl of 5.4, and the enzyme activity was optimal at 45°C and pH 6.5. The activities were strongly inhibited by Hg2+, Ag+, and p-chloromercuribenzoate, whereas less pronounced effects (5-10% inhibition) were observed in the presence of the remaining divalent cations, the chelating agent EDTA and phenanthroline. The purified enzyme hydrolyzed various insecticides with similar carboxylester. trans-Permethrin is the preferred substrate.
- Liang, Wei Q.,Wang, Zhuo Y.,Li, He,Wu, Pei C.,Hu, Ji M.,Luo, Na,Cao, Li X.,Liu, Yu H.
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p. 7415 - 7420
(2007/10/03)
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- PROCESS FOR PREPARING (+)-2-(4-CHLOROPHENYL)-3-METHYL BUTANOIC ACID
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The present invention relates to an environmentally benign process for preparation of (+)2-(4-chlorophenyl)-3-methyl butanoic acid (+ CPA) from its racemic acid, using optically active arylamines like (-) PEA in hydrophilic/hydrophobic organic solvents like butanol, propanol etc. as aqueous mixtures, separating the desired (+) CPA salt, mother liquor by filtration and refining the (+) CPA salt in the same solvent system as used for resolution, recovering the desired acid in high optical purity by extracting with aqueous mineral acid. The mother liquor is concentrated under vacuum and extracted with aqueous mineral acid to obtain undesired (-) CPA which was recovered and recycled after racemization. The aqueous mineral acid layer thus obtained is mixed with corresponding aqueous mineral acid layer obtained from (+) CPA recovery and extracted with aqueous caustic lie solution to recover the optically active amine used for resolution. Thus the method described effectively provides a process for recovery and recycle of the undesired (-) CPA, optically active amine, besides obtaining the desired (+) CPA in high optical purity.
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- A Rearrangement Route to Fenvaleric Acid
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(±)-Fenvaleric acid 2, the key intermediate for the preparation of the pesticide esfenvalerate 1, was prepared by a novel sequence which first involves the Henry reaction of 2-methyl-1-nitropropane and 4-chlorobenzaldehyde. The nitroaldol reaction provided nitroalcohol 5 which was then reduced to the corresponding aminoalcohol 6. Submission of 6 to an aminopinacol rearrangement promoted by nitrous acid deamination then afforded aldehyde 8 through a 1,2-aryl shift. The product fenvaleric aldehyde 8 was then converted to the title compound 2 by a modified Jones oxidation.
- Luzzio, Frederick A.,Fitch, Richard W.
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p. 498 - 501
(2007/10/03)
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- Chiral α-substituted carbonyls and alcohols from the S(N)2' displacement of cuprates on chiral carbonates: An alternative to the alkylation of chiral enolates
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A highly stereoselective sequence of reactions, based on the anti-selective S(N)2' addition of cuprates to allylic carbonates, transforms alkynes or alkenyl halides into carbonyls having α-chiral centers. The method, which uses menthone as a chiral auxiliary, is a useful alternative to the alkylation of chiral enolates with the added advantage of allowing for the 'alkylation' of sec- and tert-alkyl and aryl groups.
- Spino,Beaulieu,Lafreniere
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p. 7091 - 7097
(2007/10/03)
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- Process for making α,β-unsaturated carboxylic acids
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α, β-Unsaturated acids of the formula STR1 wherein R1 signifies C1 -C5 -alkyl and Ar signifies an aryl group which is optionally substituted by one or more substituents selected from the group consisting of halogen, phenyl, C1 -C5 -alkyl, C1 -C5 -alkoxy, perfluorinated C1 -C5 -alkyl or perfluorinated C1 -C5 -alkoxy can be obtained from new or known compounds of the formula STR2 Compounds I can be converted by asymmetric hydrogenation into corresponding optically active saturated acids.
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- Development of an immunoassay for the pyrethroid insecticide esfenvalerate
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A competitive enzyme-linked immunosorbent assay was developed for the detection of the pyrethroid insecticide esfenvalerate. Two haptens containing amine or propanoic acid groups on the terminal aromatic ring of the fenvalerate molecule were synthesized and coupled to carrier proteins as immunogens. Five antisera were produced and screened against eight different coating antigens. The assay that had the least interference and was the most sensitive for esfenvalerate was optimized and characterized. The I50 for esfenvalerate was 30 ± 6.2 μg/L, and the lower detection limit (LDL) was 3.0 2+ 1.8 μg/L. The assay was very selective. Other pyrethroid analogues and esfenvalerate metabolites tested did not cross-react significantly in this assay. To increase the sensitivity of the overall method, a C18 sorbent-based solid-phase extraction (SPE) was used for water matrix. With this SPE step, the LDL of the overall method for esfenvalerate was 0.1 μg/L in water samples.
- Shan, Guomin,Stoutamire, Donald W.,Wengatz, Ingrid,Gee, Shirley J.,Hammock, Bruce D.
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p. 2145 - 2155
(2007/10/03)
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- Efficient syntheses of optically active 2-arylalkanoic acids
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A highly enantioselective synthesis of 2-axylpropanoic acid was achieved, using a new developed methodology of cuprate addition to chiral carbonates derived from menthone.
- Beaulieu, Christian,Spino, Claude
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p. 1637 - 1640
(2007/10/03)
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- Practical synthesis of (S)-2-(4-fluorophenyl)-3-methylbutanoic acid, key building block for the calcium antagonist Mibefradil
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A short, technically feasible route was developed for the synthesis of (S)-2-(4-fluorophenyl)-3-methylbutanoic acid (S)-2 with an overall yield of 80% starting from 4-fluorophenylacetic acid. Asymmetric hydrogenation of the easily accessible unsaturated acid 3 in the presence of ruthenium(II) carboxylato complexes containing chiral atropisomeric diphosphines afforded (S)-2 in up to 94% ee. The ee of (S)-2 was upgraded to 98% by crystallization of its sodium salt. The same protocol was also applied to the synthesis of (S)-2-(4-chlorophenyl)-3-methylbutanoic acid.
- Crameri, Yvo,Foricher, Joseph,Scalone, Michelangelo,Schmid, Rudolf
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p. 3617 - 3623
(2007/10/03)
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- Studies on the synthesis of chiral 2-(p.chlorophenyl)-3-methylbutanoic acid, a key-precursor of Fenvalerate, by hydrocarbonylation reactions
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The preparation of racemic 2-(p.chlorophenyl)-3-methylbutanoic acid (2), a building block for (S,S)-Fenvalerate (an important broad spectrum insecticide), was effected by rhodium catalyzed hydroformylation of 2-methyl-1 -(p.chlorophenyl) propene (4) in the presence of excess of triphenylphosphine to inhibit substrate isomerization followed by mild oxidation of the resulting aldehyde 6; an overall yield of 88% was reached. Olefin 4 exhibits a very low tendency to undergo both hydrocarboethoxylation and hydrocarboxylation in the presence of palladium complexes as catalysts. Enantioselective hydrocarbonylation reactions carried out on olefin 4 afford unsatisfactory chemical and optical yields of the optically active ester 5 or acid 2. Springer-Verlag 1996.
- Botteghi, Carlo,Bona, Denis Dalla,Paganelli, Stefano,Marchetti, Mauro,Sechi, Barbara
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p. 101 - 107
(2007/10/03)
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- Enantioselective Hydrolysis of (RS)-2-isopropyl-4'-chlorophenylacetonitrile by Pseudomonas sp. B21C9
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Pseudomonal sp.B21C9, a new nitrile-degrading microorganism, was isolated from a soil sample.By a hydrolysis of (RS)-isopropyl-4'-chlorophenylacetonitrile using cells of B21C9, (S)-2-isopropyl-4'-chlorophenylacetic acid having excellent optically purity could be obtained.It appeared that the microbial hydrolysis proceeded via stepwise reactions by a nitrile hydratase having poor (S)-selectivity and an amidase having strict (S)-selectivity.
- Matsumoto, Shun-ichi,Inoue, Ayumu,Kumagai, Kazuo,Murai, Rika,Mitsuda, Satoshi
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p. 720 - 722
(2007/10/02)
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- 1,1′-binaphthalene-2,2′-diol as a chiral auxiliary. Diastereoselective alkylation of binaphthyl esters, complex-induced proximity effects in enolate formation, and one-step synthesis of an optically active β-substituted ketone
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Diastereoselective alkylation of enolates derived from (S)-naphthyl phenylacetate 1 with LDA in THF gave the S,S-isomer as a major product. The diastereoselectivity increased as the bulkiness of the alkylating agent was increased. The low diastereomeric excess (~70%) of methylation was markedly raised to 92% by the use of n-BuLi as a base due to the complex-induced proximity effect (CIPE) in enolate formation. This highly diastereoselective methylation was used to synthesize the clinically important anti-inflammatory drugs (S)-naproxen (60) and (S)-suprofen (68). The stereochemistry of ketene trimethylsilyl acetals generated from several phenylacetates was investigated to understand the origin of the diastereoselectivity in this alkylation. Methyl phenylacetate (46) predominantly gave a (Z)-enolate by kinetic deprotonation, while the (E)-enolate was predominantly obtained from phenyl phenylacetate (47). An optically active ketone (88) was synthesized from binaphthyl ester 84 by a one-pot procedure involving the 1,4-addition, followed by the 1,2-addition, of organometallics. The CIPE again played a crucial role in the high enantiomeric excess in this case.
- Tanaka, Fujie,Node, Manabu,Tanaka, Kiyoshi,Mizuchi, Maki,Hosoi, Shinzo,Nakayama, Masayo,Taga, Tooru,Fuji, Kaoru
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p. 12159 - 12171
(2007/10/03)
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- Synthesis of Optically Active α-Isopropyl-4-substituted Phenylacetic Acids by Asymmetric Hydrogenation
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Homogeneous hydrogenation of 2-phenyl-3-methyl-2-butenoic acid derivatives in the presence of a catalytic amount of such chiral phosphine-rhodium complexes as Rh/(R)-BINAP, Rh/(R)-, or (S)-Cy-BINAP, Rh/(R)-p-tolyl-BINAP, and Rh/(R)-p-methoxyphenyl-BINAP afforded the corresponding phenylacetic acid derivatives in high enantiomeric excesses and in quantitative chemical yields.The optically activa phenylacetic acid derivatives are useful intermediates of agrochemicals and pharmaceuticals.
- Takemoto, Ichiki,Kawamura, Norio,Kaminaka, Hiroshi
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p. 2071 - 2072
(2007/10/02)
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- Asymmetric Catalytic Alkylation of 4-Chlorophenylacetic Acid
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Using N-(monoalkyl)-α,β-diphenyl-β-hydroxy ethylamine as chiral ligands, 46.2percent enantiomeric excess was obtained in the asymmetric catalytic alkylation of 4-chlorophenylacetic acid.
- Mi, A. Q.,Wang, Z. Y.,Jiang, Y. Z.
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p. 1957 - 1960
(2007/10/02)
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- Process for the preparation of 2-(4-chlorophenyl)-3-methylbutyric acid
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A process for the preparation of 2-(4-chlorophenyl)-3-methylbutyric acid from 4-chlorobenzaldehyde by conversion of the benzaldehyde to 3-(4-chlorophenyl)-2-methylpropenal, 3-(4-chlorophenyl)-2-methylpropanol, 1-(4-chlorophenyl)-2-methylpropene-1, and 2-(4-chlorophenyl)-2-methylbutyraldehyde, and finally to the desired corresponding butyric acid.
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- Process for the preparation of optically active alpha-acrylalkanoic acids and novel intermediates thereof
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A new enantioselective process is described for preparing optically active alpha-arylalkanoic acids by: (a) halogenation on the aliphatic carbon atom alpha to the ketal group, of ketals of formula STR1 in which Ar represents an aryl, optionally substituted; R represents a C1 -C4 alkyl; R1 and R2, represents a hydroxy, a O- M+, OR3 or NR4 R5 group; the carbon atoms indicated by an asterisk both simultaneously are in (R) or (S) configuration. This reaction is diastereoselective, so that a mixture of alpha-haloketals is obtained in which one of the two epimers prevails, and generally strongly prevails, over the other. (b) rearrangement of the haloketals of formula STR2 in which X is Cl, Br or I to alpha-arylalkanoic acids in a single stage or in two successive stages, by way of esters of formula STR3 The compounds (A) and (C) are all new compounds. The rearrangement step (b) may be performed under new, inventive conditions. The esters of formula (C) have pharmacological activity analogous to that of the corresponding alpha-arylalkanoic acids.
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- ENZYMATIC RESOLUTION OF METHYL 2-ALKYL-2-ARYLACETATES
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Horse liver esterase, used as its inexpensive commercial acetone powder, catalyzes the selective hydrolysis of methy 2-alkyl-2-arylacetates to afford R(-)-2-alkyl-2-arylacetic acids and S(+)-methyl 2-alkyl-2-arylacetates.
- Ahmar, M.,Girard, C.,Bloch, R.
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p. 7053 - 7056
(2007/10/02)
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- Process for preparing optically active arylacetic acid derivative
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An optically active arylacetic acid derivative of the formula: STR1 wherein R1 and R2 are the same or different and are each an hydrogen atom, a lower alkyl group or a phenyl group; and Ar is a group of the formula: STR2 a group of the formula: STR3 wherein R3 and R4 are the same or different and are each a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a difluoromethoxy group, a trifluoromethyl group or a phenyl group is prepared in good conversion and optical yield by asymmetrically reducing an ethylenically unsaturated compound of the formula: STR4 wherein R1, and R2 and Ar are the same as defined above with hydrogen in the presence of a metal catalyst modified with a ligand selected from the group consisting of a specific optically active metallocenyl phosphine derivative and a specific optically active binaphthyl derivative.
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- Process for the preparation of optically active alpha-arylalkanoic acids and novel intermediates thereof
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A new enantioselective process is described for preparing optically active alpha-arylalkanoic acids by: (a) halogenation on the aliphatic carbon atom alpha to the ketal group, of ketals of formula STR1 in which Ar represents an aryl, optionally substituted; R represents a C1 -C4 alkyl; R1 and R2, represents a hydroxy, a O- M+, OR3 or NR4 R5 group; the carbon atoms indicated by an asterisk both simultaneously are in (R) or (S) configuration. This reaction is diastereoselective, so that a misture of alpha-haloketals is obtained in which one of the two epimers prevails, and generally strongly prevails, over the other. (b) rearrangement of the haloketals of formula STR2 in which X is Cl, Br or I to alpha-arylalkanoic acids in a single stage or in two successive stages, by way of esters of formula STR3 The compounds (A) and (C) are all new compounds. The rearrangement step (b) may be performed under new, inventive conditions. The esters of formula (C) have pharmacological activity analogous to that of the corresponding alpha-arylalkanoic acids.
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- Tartaric Acid, an Efficient Chiral Auxiliary: New Asymmetric Synthesis of 2-Alkyl-2-arylacetic Acids
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A highly enantioselective synthesis of 2-alkyl-2-arylacetic acids, an important class of antiinflammatory agents, based on a new diastereoselective α-bromination of homochiral acetals 1 and on the stereospecific silver-promoted rearrangement of the corresponding homochiral α-bromo acetals 2 and 3, is reported.The new methodology represents a meaningful example of the use of tartaric acid as efficient and economic chiral auxiliary.The asymmetric bromination of 1 is of general character and occurs with very high diastereoselectivity, even at room temperature; a mechanism for the new reaction is proposed.The overall process has been successfully applied to the preparation of enantiomerically pure 2-alkyl-2-arylacetic acids, among them (2S)-(+)-2-(6-methoxy-2-naphthyl)propanoic acid (Naproxen)
- Castaldi, Graziano,Cavicchioli, Silvia,Giordano, Claudio,Uggeri, Fulvio
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p. 3018 - 3027
(2007/10/02)
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- Racemization of optically active 2-(4-chlorophenyl)-3-methylbutyric acid
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A method for racemization of optically active 2-(4-chlorophenyl)-3-methylbutyric acid which comprises the steps of (a) reacting optically active 2-(4-chlorophenyl)-3-methylbutyric acid with a hydroxide or carbonate of an alkali metal or alkaline earth metal at a temperature of more than 110° C. to produce a racemate of the alkali metal or alkaline earth metal salt of the above acid, and (b) converting the resulting racemate of the salt to the acid.
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- (S) α-Cyano-3-phenoxy-benzyl alcohol
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(S) α-cyano-3-phenoxy-benzyl alcohol having the formula STR1 and a novel process for its preparation and novel intermediates.
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- Inert organic solvent dispersion of alkali hydroxide and reaction using the same
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An inert organic solvent dispersion of alkali hydroxide is prepared by mixing an alkali hydroxide, an inert organic solvent and a stabilizer and heating and stirring at the temperature for forming the pasty alkali hydroxide and cooling the dispersion. The dispersion of alkali hydroxide is used in a reaction of an active methylene compound with an organoalkyl halide such as a reaction of a halophenylacetonitrile with an isopropyl halide to obtain α-isopropyl halophenylacetonitrile.
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- Substituted pyridine methyl esters of 2-isopropyl-2-(4-chlorophenyl)acetic acid and their use as insecticides
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Substituted pyridine methyl esters of 2-isopropyl-2-(4-chlorophenyl)acetic acid are prepared which correspond to the formula: STR1 wherein n represents an integer of 0 to 2; X independently represents alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, alkylthio of 1 to 4 carbon atoms, alkylsulfinyl of 1 to 4 carbon atoms, alkylsulfonyl of 1 to 4 carbon atoms, trifluoromethyl, nitro, cyano, chloro, fluoro, bromo, or 3,4-methylenedioxy (when n is 2 and both X's are taken together); and R represents hydrogen, cyano or ethynyl. These compounds have been found to exhibit a high degree of insecticidal activity and compositions containing said compounds are so employed.
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- Process for preparing phenyl-acetic acid esters
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A process for preparing a substituted phenyl-acetic acid ester of the formula (I), SPC1 wherein R1 is an ethyl group or an isopropyl group, R2 is a hydrogen atom, a C1 -C4 alkyl group, a methoxy group, a halogen atom or a methylenedioxy group, which comprises reacting a quaternary ammonium salt of the formula (III), SPC2 wherein X is a halogen atom, and A is an alkylamine, pyridine or an N-alkylaniline, with a carboxylic acid of the formula (II), SPC3 wherein R1 and R2 are each as defined above, its reactive derivative, or a mixture of the acid and its reactive derivative.
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