- Dioxazocinium ortho esters: A class of highly pH-vulnerable amphiphiles
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Making and breaking lipids: A general synthesis of a new class of ortho ester lipids from a dioxazocinium ketene acetal is disclosed. Both single- and dual-chain analogues were prepared, and the most sensitive of these (see structure) was shown to disassemble at 38 °C within 6 h at pH 5.0.
- By, Kolbot,Nantz, Michael H.
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Read Online
- Expanding ester biosynthesis in Escherichia coli
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To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l -1). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.
- Rodriguez, Gabriel M,Tashiro, Yohei,Atsumi, Shota
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p. 259 - 265
(2014/04/03)
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- Synthesis of C7-C16-Alkyl maltosides in the presence of tin(IV) chloride as a lewis acid catalyst
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The synthesis of C7- to C16-alkyl maltosides in the presence of tin(IV) chloride as Lewis acid catalyst was performed. The characterization of the products and theoretical investigation of the crucial step in the synthesis were carried out. The preparation of the β-maltosides required reaction time of 1 h, and that of the α-maltosides was 72 h. The side products were the α-D-maltosidechloride and 2-hydroxy-β-maltoside, respectively. The PM3 calculation confirmed the formation of the kinetically controlled β-product.
- Markovic, Zoran,Predojevic, Jasmina,Manojlovic, Nedeljko T.
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experimental part
p. 83 - 90
(2012/05/20)
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- Structure-Activity relationship of aliphatic compounds for nematicidal activity against pine wood nematode (Bursaphelenchus xylophilus)
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Nematicidal activity of aliphatic compounds was tested to determine a structure-activity relationship. There was a significant difference in nematicidal activity among functional groups. In a test with alkanols and 2E-alkenols, compounds with C8-C11 chain length showed 100% nematicidal activity against pine wood nematode, Bursaphelenchus xylophilus, at 0.5 mg/mL concentration. C6-C10 2E-alkenals exhibited >95% nematicidal activity, but the other compounds with C 11-C14 chain length showed weak activity. Nematicidal activity of alkyl acetates with C7-C11 chain length was strong. Compounds belonging to hydrocarbons, alkanals, and alkanoic acetates showed weak activity at 0.5 mg/mL concentration. Nematicidal activity of active compounds was determined at lower concentrations. At 0.25 mg/mL concentration, whole compounds except C8 alkanol, C8 2E-alkenol, and C7 alkanoic acid showed >80% nematicidal activity. C 9-C11 alkanols, C10-C11 2E-alkenols, C8-C9 2E-alkenals, and C9-C10 alkanoic acids showed >80% nematicidal activity at 0.125 mg/mL concentration. Only C11 alkanol exhibited strong nematicidal activity at 0.0625 mg/mL concentration, the lowest concentration that was tested. 2010 American Chemical Society.
- Seo, Seon-M.I.,Junheon, Kim,Eunae, Kim,Park, Hye-M.I.,Kim, Young-Joon,Park, I.L.-Kwon
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experimental part
p. 1823 - 1827
(2010/09/09)
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- Separation, recovery and reuse of N-heterocyclic carbene catalysts in transesterification reactions
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A novel and convenient strategy to separate, recover and reuse N-heterocyclic carbene catalysts in transesterification reactions has been developed.
- Zeng, Tieqiang,Song, Gonghua,Li, Chao-Jun
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supporting information; experimental part
p. 6249 - 6251
(2010/02/16)
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- BF3 etherate-induced formation of C7-C 16-alkyl β-D-glucopyranosides
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BF3 etherate-induced formation of C7-C 16-alkyl D-glucopyranosides is used as the key step in their synthesis from glucose and C7-C16-alkanols.
- Petrovic, Zorica,Konstantinovic, Stanimir,Spasojevic, Aleksandra
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p. 132 - 134
(2007/10/03)
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- Synthesis of C7-C16-alkyl glycosides: Part III - Synthesis of alkyl D-galactopyranosides in the presence of tin(IV) chloride as a Lewis acid catalyst
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The Lewis acid catalyzed glycosylation reaction of β-peracetylated sugar derivative (galactose) with fatty alkanols is used in a synthesis of C7-C16-alkyl galactopyranosides. The process occurs under the influence of tin(IV) chloride as a Lewis acid catalyst.
- Konstantinovi?,Dimitrijevi?,Radulovi?
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p. 598 - 603
(2007/10/03)
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- Reptilian chemistry: volatile compounds from paracloacal glands of the American crocodile (Crocodylus acutus).
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The secretion of the paracloacal glands of the American crocodile (Crocodylus acutus) contains over 80 lipophilic compounds, including saturated and unsaturated long-chain alcohols along with their formic, acetic, and butyric acid esters, and several isoprenoids. Most of these compounds were identified on the basis of mass spectra, obtained by GC-MS. In addition, identification of the major components was supported by infrared spectra obtained by GC-FTIR. Major differences are indicated in the composition of the paracloacal gland secretion of C. acutus and that of another crocodylid, the African dwarf crocodile (Osteolaemus tetraspis).
- Garcia-Rubio, Silvina,Attygalle, Athula B,Weldon, Paul J,Meinwald, Jerrold
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p. 769 - 781
(2007/10/03)
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- Behavioral responses of Spodoptera littoralis males to sex pheromone components and virgin females in wind tunnel
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The major component of the sex pheromone of female Spodoptera littoralis, (Z,E)-9,11-tetradecadienyl acetate (1), elicited all steps of the male behavioral sequence, i.e., wing fanning and taking flight, oriented upwind flight and arrival to the middle of the tunnel, close approach and contact with the source. The activity was equivalent to that elicited by virgin females. In the range of doses tested, the dosage of 1 had no significant effect on the number of source contacts. Male response was significantly affected by light intensity, being optimum at 3 lux. Activity of the minor components (Z)-9-tetradecenyl acetate (2), (E)-11-tetradecenyl acetate (3), tetradecyl acetate (4), (Z)-11-tetradecenyl acetate (5), and (Z,E)-9,12-tetradecadienyl acetate (6) was significantly lower than that of the major component when assayed individually. In multicomponent blends compound 4 appeared to strongly decrease the number of males arrested at the source, the effect being particularly important when compound 5 was present in the blend. Results of single sensillum experiments confirmed the existence of two main physiologically distinct sensillar types. The most common type of sensilla contained a neuron that responded specifically to compound 1. A second type of sensilla, located laterally on the ventral sensory surface, contained two receptor neurons responding to compound 6 and to (Z)-9-tetradecenol. Among short sensilla, one hair responded to compound 4 and could represent a minor sensillar type. No sensory neuron was found to detect the other minor pheromone compounds 2, 3, and 5,.
- Quero, Carmen,Lucas, Philippe,Renou, Michel,Guerrero, Angel
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p. 1087 - 1102
(2007/10/03)
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