- Attempted Synthesis of (9Z)-Methyl 12-Hydroperoxyoctadec-9-enoate
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The silver trifluoroacetate-assisted reaction of alkyl halides with hydrogen peroxide has been investigated.Methyl 12-bromostearate furnished, for the first time, methyl 12-hydroperoxystearate in 34percent yield.Methyl 12-bromo-oleate, however, gave cyclopropane hydroperoxides (via a homoallylic cation rearrangement) and hydroperoxy epidioxides (presumably via methyl 12-hydroperoxyoleate which could not be isolated).Methyl 9-t-butylperoxy-10,11-methyleneheptadecanoate was produced by the reaction of methyl 12-bromo-oleate with t-butyl hydroperoxide in the presence of silver trifluoroacetate.None of these transformations occurred when silver trifluoroacetate was replaced by the acetate.
- Bascetta, Emanuele,Gunstone, Frank D.
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- Uncovering potential interspecies signaling factors in plant-derived mixed microbial culture
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Microbes use signaling factors for intraspecies and interspecies communications. While many intraspecies signaling factors have been found and characterized, discovery of factors for interspecies communication is lagging behind. To facilitate the discovery of such factors, we explored the potential of a mixed microbial culture (MMC) derived from wheatgrass, in which heterogeneity of this microbial community might elicit signaling factors for interspecies communication. The stability of Wheatgrass MMC in terms of community structure and metabolic output was first characterized by 16S ribosomal RNA amplicon sequencing and liquid chromatography/mass spectrometry (LC/MS), respectively. In addition, detailed MS analyses led to the identification of 12-hydroxystearic acid (12-HSA) as one of the major metabolites produced by Wheatgrass MMC. Stereochemical analysis revealed that Wheatgrass MMC produces mostly the (R)-isomer, although a small amount of the (S)-isomer was also observed. Furthermore, 12-HSA was found to modulate planktonic growth and biofilm formation of various marine bacterial strains. The current study suggests that naturally derived MMCs could serve as a simple and reproducible platform to discover potential signaling factors for interspecies communication. In addition, the study indicates that hydroxylated long-chain fatty acids, such as 12-HSA, may constitute a new class of interspecies signaling factors.
- Domzalski, Alison,Henderson, Douglas P.,Kawamura, Akira,Oldham, Athenia L.,Pasolli, Hilda Amalia,Perez, Susan D.,Velasquez, Alexandria,Vigo, Valeria,Yoo, Barney
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- A General Approach to Intermolecular Olefin Hydroacylation through Light-Induced HAT Initiation: An Efficient Synthesis of Long-Chain Aliphatic Ketones and Functionalized Fatty Acids
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Herein, an operationally simple, environmentally benign and effective method for intermolecular radical hydroacylation of unactivated substrates by employing photo-induced hydrogen atom transfer (HAT) initiation is described. The use of commercially available and inexpensive photoinitiators (Ph2CO and NHPI) makes the process attractive. The olefin hydroacylation protocol applies to a wide array of substrates bearing numerous functional groups and many complex structural units. The reaction proves to be scalable (up to 5 g). Different functionalized fatty acids, petrochemicals and naturally occurring alkanes can be synthesized with this protocol. A radical chain mechanism is implicated in the process.
- Guin, Joyram,Paul, Subhasis
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supporting information
p. 4412 - 4419
(2021/02/05)
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- A Bi-Enzymatic Cascade Pathway towards Optically Pure FAHFAs**
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Recently discovered endogenous mammalian lipids, fatty acid esters of hydroxy fatty acids (FAHFAs), have been proved to have anti-inflammatory and anti-diabetic effects. Due to their extremely low abundancies in vivo, forging a feasible scenario for FAHFA synthesis is critical for their use in uncovering biological mechanisms or in clinical trials. Here, we showcase a fully enzymatic approach, a novel in vitro bi-enzymatic cascade system, enabling an effective conversion of nature-abundant fatty acids into FAHFAs. Two hydratases from Lactobacillus acidophilus were used for converting unsaturated fatty acids to various enantiomeric hydroxy fatty acids, followed by esterification with another fatty acid catalyzed by Candida antarctica lipase A (CALA). Various FAHFAs were synthesized in a semi-preparative scale using this bi-enzymatic approach in a one-pot two-step operation mode. In all, we demonstrate that the hydratase-CALA system offers a promising route for the synthesis of optically pure structure-diverse FAHFAs.
- Zhang, Yan,Eser, Bekir Engin,Guo, Zheng
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p. 2146 - 2153
(2021/05/07)
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- Efficient flow fischer esterification of carboxylic acids with alcohols using sulfonic acid-functionalized silica as supported catalyst
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Flow Fischer esterification of carboxylic acids using hydroxy-substituted sulfonic acid-functionalized silica (HOSAS) packed into a stainless steel column reactor was investigated. HO-SAS well catalyzed flow esterification of long chain carboxylic acids with methanol within 3min of residence time at 110°C, and the methyl esters were quantitatively obtained. The flow esterification protocol was applied to the synthesis of a variety of esters (19 examples) and scalable synthesis was also successful.
- Furuta, Akihiro,Fukuyama, Takahide,Ryu, Ilhyong
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p. 607 - 612
(2017/06/19)
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- Use of esters or amides of hydroxylated carboxylic acids as solubilizers
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The use of esters or amides of hydroxylated carboxylic acids as solubilizers, particularly for pharmaceutical, cosmetic and food preparations, is described.
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- A mild and efficient method for esterification and transesterification catalyzed by iodine
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Iodine, was found to be a practical and useful Lewis acid catalyst for the esterification of carboxylic acids with alcohols. The high catalytic activity of iodine can be used for the transesterification of esters by different alcohols including tertiary alcohols and sterically hindered primary and secondary alcohols. The method presented is especially effective for simultaneous esterification and transesterification reactions.
- Ramalinga,Vijayalakshmi,Kaimal
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p. 879 - 882
(2007/10/03)
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- A new family of polymerizable lyotropic liquid crystals: Control of feature size in cross-linked inverted hexagonal assemblies via monomer structure
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An efficient and versatile synthesis of a series of polymerizable amphiphilic mesogens that affords control over tail length and position of the polymerizable group is described. The synthesis employs a novel and facile method of preparing styrene ethers. The monomers are sodium salts of styrene ether-modified fatty acids that can be used to form cross-linkable inverted hexagonal (HII) lyotropic liquid crystal (LLC) phases at ambient temperature with controllable nanometer-scale dimensions. Examination of a series of regioisomers with the same alkyl chain length but with the styrene ether group at different locations along the chain revealed that the position of the styrene ether has a profound effect on the dimensions of the resulting HII phase at a fixed temperature and composition. Increasing overall monomer tail length also has a significant, although smaller, effect on the unit cell dimensions of the LLC phase. By controlling the structure of the LLC monomer in this manner, cross-linked HII phases with interchannel distances (ICD) ranging from 29 to 54 A can be obtained. Furthermore, changing the counterion from Na+ to tetraalkylammonium ions leads to further expansion of the HII unit cell to a maximum ICD of 65 A, as well as to the production of a lamellar phase. Use of these monomers affords a new and unparalleled degree of control over phase structure and dimensions for the production of nanostructured organic materials.
- Reppy,Gray,Pindzola,Smithers,Gin
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p. 363 - 371
(2007/10/03)
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- Properties of unusual phospholipids. III: Synthesis, monolayer investigations and DSC studies of hydroxy octadeca(e)noic acids and diacylglycerophosphocholines derived therefrom
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Diacylglycerophosphocholines containing (R)-3-, (R)-12-, (R)-17-hydroxy octadeca(e)noic acids and the corresponding racemates were synthesized and purified to homogeneity. The influence of the position of the hydroxy group on the monolayer packing properties of these fatty acids and their phosphatidylcholines was studied by Langmuir techniques and 1,2-di-[(R)-12-hydroxy-octadec-cis-9-enyl]-sn-glycero-3-phosphocholine displayed the largest lift-off area (330 A2/molecule). This result was in line with the thermotropic phase behavior of these phospholipids, as measured by differential scanning calorimetry (DSC): the gel- to liquid-crystalline phase transition temperature (T(m))passed through a minimum of -15.1°C for 1,2-di-[(R)-12-hydroxy-octadec-cis-9-enyl]-sn-glycero-3-phosphocholine.
- Negelmann, Lars,Pisch, Sandra,Bornscheuer, Uwe,Schmid, Rolf D.
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p. 117 - 134
(2007/10/03)
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- Intramolecular palladium-catalysed cross coupling; a direct route to γ-oxo-α,β-unsaturated macrocycles
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Intramolecular Pd0-catalysed cross coupling of structures terminating in an acyl chloride and a β-stannylalkenoate has provided a new and an efficient route to 10-20 membered γ-oxo-α,β-unsaturated macrolides. Both the Z and E-β-stannylalkenoates afforded identical macrocyclic products demonstrating that under the reaction conditions thermodynamic equilibration of the first formed cross coupled product was most probably occurring. The method has been used to synthesise the macrocylic framework of the antibiotic A26771B and norpatulolide B.
- Baldwin, Jack E.,Adlington, Robert M.,Ramcharitar, Steve H.
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p. 2957 - 2976
(2007/10/02)
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- Stereochemistry of Olefin and Fatty Acid Oxidation. Part 3. The Allylic Hydroperoxides from the Autoxidation of Methyl Oleate
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Methods have been developed, using 13C n.m.r. spectroscopy and mass spectrometry, for the analysis of all eight cis and trans allylic 8-, 9-, 10-, and 11-hydroperoxides formed on autoxidation of methyl oleate.
- Frankel, Edwin N.,Garwood, Robert F.,Khambay, Bhupinder P. S.,Moss, Gerard P.,Weedon, Basil C. L.
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p. 2233 - 2240
(2007/10/02)
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- Synthesis, Characterisation, and Transformations of a Lipid Cyclic Peroxide
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Photosensitised oxidation of (9E,11E)-methyl octadeca-9,11-dienoate gave an unsaturated cyclic peroxide (epidioxide) in high yield.This was characterised spectroscopically.The peroxide underwent facile rearrangement to a furanoid ester under a variety of reaction conditions.Catalytic reduction of the unsaturated peroxide cleaved the O-O bond.Bromination and epoxidation gave dibromo and epoxy esters respectively with the peroxide group still intact.
- Bascetta, Emanuele,Gunstone, Frank D.,Scrimgeour, Charles M. S.
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p. 2199 - 2206
(2007/10/02)
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