- Chemistry of metapleural gland secretions of three attine ants, Atta sexdens rubropilosa, Atta cephalotes, and Acromyrmex octospinosus (Hymenoptera: Formicidae)
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The chemical composition of the secretions of the metapleural glands of workers and soldiers of two Atta species, atta sexdens rubropilosa and A. cephalotes, and workers of Acromyrmex oetospinoxus, has been studied. As indicated by infrared spectrometry and confirmed by the ninhydrin test, the secretions contain chiefly proteins. Of the volatile acidic portion, which is present as ionized salts, phenylacetic acid is the major component in workers and soldiers of A. s. rubropilosa and A. cephalotes. Both Atta species also contain 3 hydroxydecanoic acid and its homolog as minor components together with indoleacetic acid. While there are qualitative similarities in the acidic composition in the secretions of A. s. rubropilosa and A. cephalotes, they differ quantitatively. The secretion of Acromyrmex octospinosus contains 3-hydoxydecanoic and indoleacetic acids, but lacks phenylacetic acid The bactericidal and fungicidal actions of the three major substances have been confirmed.
- Do Nascimento, Ruth R.,Schoeters, Eric,Morgan, E. David,Billen, Johan,Stradling, David J.
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- 15(R)-hydroxylinoleic acid, an oxylipin from oat seeds
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A new oxylipin, 15(R)-hydroxy-9(Z),12(Z)-octadecadienoic acid (15(R)- hydroxylinoleic acid), was isolated from oat seeds. Its structure was determined by chemical and spectroscopic methods. Oat seeds contained 0.6- 0.7 mg g-1 of the new compound in esterified form. The amounts found in seeds of harley, rye and wheat, however, were less than 1 μg g-1.
- Hamberg, Mats,Hamberg, Gunvor
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- Diastereoselective Synthesis of 2,5-Dialkyl Tetrahydrofuran-3-ones by a Copper-Catalysed Tandem Carbenoid Insertion and Ylide Rearrangement Reaction
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Cu(acac)2-catalysed cyclisations of the α-diazo ketones 3, result in the diastereoselective formation (>97:3) of the trans-2,5-dialkyl tetrahydrofuran-3-ones 4.The yields and levels of diastereoselection are catalyst, solvent, and temperature dependent.
- Clark, J. Stephen
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- PODOBLASTIN A, B AND C. NEW ANTIFUNGAL 3-ACYL-4-HYDROXY-5,6-DIHYDRO-2-PYRONES OBTAINED FROM PODOPHYLLUM PELTATUM L
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The potent antifungal constituent against Pyricularia oryzae Cav. obtained from Podophyllum peltatum L. has been disclosed to be a mixture of three new 3-acyl-4-hydroxy-5,6-dihydropyrones (podoblastin A, B and C).The absolute configuration at C-6 of podoblastins was determined to be (R).
- Miyakado, Masakazu,Inoue, Satoru,Tanabe, Yoo,Watanabe, Keisuke
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- ASYMMETRIC SYNTHESIS OF (S)-METHYL-3-HYDROXYALKANOATES FROM KETENE AND 2,2-DICHLOROALDEHYDES VIA 4-(1,1-DICHLOROALKYL)-2-OXETANONES
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Using the quinidine catalyzed cycloaddition reaction of ketene and 2,2-dichloroaldehydes, the preparation of several optically pure (S)-methyl-3-hydroxyalkanoates is reported.
- Ketelaar, Peter E.F.,Staring, Emiel G.J.,Wynberg, Hans
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- Deoxyalkoxyamination of Alcohols for the Synthesis of N-Alkoxy-N-alkylbenzenesulfonamides
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A novel protocol for the deoxyalkoxyamination of alcohols has been developed, using N-alkoxybenzenesulfonimide (NOSI) as both a sulfonyl transfer reagent and an alkoxyamine source, accessing a diverse range of N-alkoxy-N-alkylbenzenesulfonamides with excellent isolated yields. This method is characterized by metal-free reaction, scalability, and waste-balance. Chiral substrates are converted with excellent levels of stereochemical inversion. NOSI could be generated in situ during the reaction as a stable reagent if a three-component one-pot reaction was designed. Exploiting this approach to run intramolecular reactions offered various N-protected isoxazolidines. In addition, valuable O-alkyl hydroxylamines (or isoxazolidines) were obtained through a neutral strategy of desulfonylation of the products.
- Sun, Qi-An,Lu, Ze-Hai,Pu, Xiao-Qiu,Hu, Hui-Lian,Zhang, Jia-heng,Yang, Xian-Jin
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supporting information
p. 3920 - 3927
(2018/07/31)
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- Inversion of cpADH5 Enantiopreference and Altered Chain Length Specificity for Methyl 3-Hydroxyalkanoates
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Expanding the substrate scope of enzymes opens up new routes for synthesis of valuable chemicals. Ketone-functionalized fatty acid derivatives and corresponding chiral alcohols are valuable building blocks for the synthesis of a variety of chemicals including pharmaceuticals. The alcohol dehydrogenase from Candida parapsilosis (cpADH5) catalyzes the reversible oxidations of chiral alcohols and has a broad substrate range; a challenge for cpADH5 is to convert alcohols with small substituents (methyl or ethyl) next to the oxidized alcohol moiety. Molecular docking studies revealed that W286 is located in the small binding pocket and limits the access to substrates that contain aliphatic chains longer than ethyl substituent. In the current manuscript, we report that positions L119 and W286 are key residues to boost oxidation of medium chain methyl 3-hydroxy fatty acids; interestingly the enantiopreference toward methyl 3-hydroxybutyrate was inverted. Kinetic characterization of W286A showed a 5.5 fold increase of Vmax and a 9.6 fold decrease of Km values toward methyl 3-hydroxyhexanoate (Vmax: 2.48 U mg? and Km: 4.76 mm). Simultaneous saturation at positions 119 and 286 library yielded a double mutant (L119M/W286S) with more than 30-fold improved activity toward methyl 3-hydroxyoctanoate (WT: no conversion; L119M/W286S: 30 %) and inverted enantiopreference (S-enantiomer ≥99 % activity decrease and R-enantiomer >20-fold activity improvement) toward methyl 3-hydroxybutyrate.
- Ensari, Yunus,Dhoke, Gaurao V.,Davari, Mehdi D.,Bocola, Marco,Ruff, Anna Jo?lle,Schwaneberg, Ulrich
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p. 12636 - 12645
(2017/09/18)
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- Characterization of FabG and FabI of the Streptomyces coelicolor dissociated fatty acid synthase
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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.
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p. 631 - 640
(2015/03/31)
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- The synthesis of medium-chain-length β-hydroxy esters via the reformatsky reaction
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The synthesis of medium-chain-length β-hydroxy esters in good yield via the Reformatsky reaction is described. This work will be used as the basis for further investigation of hydroxyalkanoate polymers as potential feedstock for biofuel production.
- Sailer, Miloslav,Dubicki, Krystyn I.,Sorensen, John L.
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- Site-selective aliphatic C-H bromination using N -bromoamides and visible light
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Transformations that selectively functionalize aliphatic C-H bonds hold significant promise to streamline complex molecule synthesis. Despite the potential for site-selective C-H functionalization, few intermolecular processes of preparative value exist. Herein, we report an approach to unactivated, aliphatic C-H bromination using readily available N-bromoamide reagents and visible light. These halogenations proceed in useful chemical yields, with substrate as the limiting reagent. The site selectivities of these radical-mediated C-H functionalizations are comparable (or superior) to the most selective intermolecular C-H functionalizations known. With the broad utility of alkyl bromides as synthetic intermediates, this convenient approach will find general use in chemical synthesis.
- Schmidt, Valerie A.,Quinn, Ryan K.,Brusoe, Andrew T.,Alexanian, Erik J.
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supporting information
p. 14389 - 14392
(2014/12/10)
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- One step catalytic conversion of cellulose to sustainable chemicals utilizing cooperative ionic liquid pairs
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A 100% conversion of cellulose to industrially useful chemicals is, for the first time, achieved in a single pot reaction by the use of cooperative ionic liquid pairs for combined dissolution and catalytic degradation of cellulose, which overcomes the long intrinsic phase problem in the conversion of biomass to chemicals.
- Long, Jinxing,Guo, Bin,Li, Xuehui,Jiang, Yanbin,Wang, Furong,Tsang, Shik Chi,Wang, Lefu,Yu, Kai Man K.
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supporting information; experimental part
p. 2334 - 2338
(2011/10/12)
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- Polyhydroxyalkanoate and manufacturing method thereof
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To provide a novel polyhydroxyalkanoate and a manufacturing method by a microorganism capable of substantially reducing unintended monomer units and obtaining the polyhydroxyalkanoate in a high yield. A microorganism capable of synthesizing a novel polyhydroxyalkanoate having 3-hydroxy-substituted benzoylalkanoic acid as a monomer unit using a substituted benzoylalkanoic acid as a material is cultured in the medium containing a substituted benzoylalkanoic acid, then the polyhydroxyalkanoate produced in the cultured bacteria is extracted and recovered.
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Page/Page column 49-50
(2008/06/13)
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- Bromolysis and iodolysis of α,β-epoxycarboxylic acids in water catalyzed by indium halides
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The ring opening of α,β-epoxycarboxylic acids by bromide and iodide ions has been efficiently carried out in water in high regio- and stereoselective fashion. The iodolysis of trans-β-monoalkylated epoxycarboxylic acids at pH 4.0 was completely α-regioselective and anti diastereoselective. The InCl3-catalyzed iodolysis of a variety of α,β-epoxycarboxylic acids at pH 1.5 gave the corresponding anti β-iodohydrins in 88-95% yields. The one-pot synthesis of the α- and β-hydroxyhexanoic acids, starting from the corresponding α,β-epoxycarboxylic acid 1a by iodolysis followed by reduction of the resulting iodohydrins 4a and 4b by NaBH4-InCl3 in water, has been performed.
- Amantini,Fringuelli,Pizzo,Vaccaro
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p. 4463 - 4467
(2007/10/03)
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- The organoselenium-mediated reduction of α,β-epoxy ketones, α,β-epoxy esters, and their congeners to β-hydroxy carbonyl compounds: Novel methodologies for the synthesis of aldols and their analogues
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Novel methods for the reduction of α,β-epoxy ketones, α,β-epoxy esters (glycidic esters), and their congeners to β-hydroxy carbonyl compounds (aldols) by the use of organoselenium reagents are described. The reagents, a sodium phenylseleno(triethyl)borate complex Na[PhSeB(OEt)3] easily prepared by reduction of (PhSe)2 with NaBH4 in EtOH and benzeneselenol (PhSeH) generated in situ from the borate complex by addition of acetic acid, have been demonstrated to serve as excellent reducing agents for these transformations. The organoselenium-mediated reduction of α,β-epoxy carbonyl compounds regiospecifically occurs at the α-carbon to produce a wide variety of cyclic (intramolecular) aldols as well as acyclic (intermolecular) ones in excellent yields. Quantitative mechanistic studies have revealed that the organoselenium-mediated reduction proceeds via an α-substitution process in contrast to the common electron transfer reducing agents.
- Miyashita, Masaaki,Suzuki, Toshio,Hoshino, Masahide,Yoshikoshi, Akira
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p. 12469 - 12486
(2007/10/03)
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- An Efficient Method for the Direct Peroxygenation of Various Olefinic Compounds with Molecular Oxygen and Triethylsilane Catalyzed by a Cobalt(II) Complex
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An efficient method for the direct peroxygenation of various olefinic compounds with molecular oxygen and triethylsilane (Et3SiH) was developed by the use of a catalytic amount of a bis(1,3-diketonato)cobalt(II) complex.According to the above method, 1-phenyl-3-triethylsilyldioxybutane (2) was directly produced from 4-phenyl-1-butene (1) by means of a reaction with O2 and Et3SiH at room temperature.Styrene (3) and ethyl acrylate (5a) were also smoothly peroxygenated to give 1-phenyl-1-triethylsilyldioxyethane (4) and ethyl 2-triethylsilyldioxypropionate (6a) by using a small amount of t-BuOOH as an initiator.The successive desilylation of 6a and reduction of the resulting ethyl 2-hydroperoxypropionate (8a) afforded the corresponding alcohol, ethyl lactate (10a), in a high yield.The synthetic utility of the present peroxygenation reaction was demonstrated in the preparation of α-hydroxy esters 10a-e from several α,β-unsaturated esters 5a-e via the corresponding triethylsilyldioxy derivatives.
- Isayama, Shigeru
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p. 1305 - 1310
(2007/10/02)
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- Organoselenium-mediated Reduction of α,β-Epoxy Esters to β-Hydroxy Esters
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α,β-Epoxy esters were reduced to β-hydroxy esters with an organoselenium reagent, Na+-, via α-substitution process.
- Miyashita, Masaaki,Hoshino, Masahide,Suzuki, Toshio,Yoshikoshi, Akira
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p. 507 - 508
(2007/10/02)
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- (R)- AND (S)-2-ACETOXY-1,1,2-TRIPHENYLETHANOL - EFFECTIVE SYNTHETIC EQUIVALENTS OF A CHIRAL ACETATE ENOLATE
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The enolate 3, easily available by double deprotonation of (R)-2-acetoxy-1,1,2-triphenylethanol (5), adds in a highly stereoselective manner to aldehides.Hydrolysis of the adducts 6/7 affods the acids 2.
- Braun, Manfred,Devant, Ralf
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p. 5031 - 5034
(2007/10/02)
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