- Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
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The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
- Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
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p. 302 - 305
(2022/01/03)
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- A Method for preparing alpha-olefins from Biomass-derived fat and oil
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The present invention relates to a method for preparing alpha-olefins from biomass-derived fats and oils. According to the preparation method, all of the various saturated or unsaturated fatty acids in the biomass-derived fats and oils can be prepared into alpha-olefins, and a conventional problem that the saturated fatty acids do not participate in a reaction or a mixture is generated due to polyunsaturated fatty acids can be solved. Thus, the present invention can be advantageously used to prepare alpha-olefins from biomass.
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Paragraph 0145; 0148-0151
(2020/09/22)
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- Mapping the Binding Motifs of Deprotonated Monounsaturated Fatty Acids and Their Corresponding Methyl Esters within Supramolecular Capsules
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A suite of NMR techniques revealed that a cavitand (1) formed 2:1 host-guest complexes with a range of monounsaturated fatty carboxylates and their corresponding methyl esters. All of the carboxylates bound to the capsule in a J-shaped motif with the carboxylate at the equatorial region of the dimeric capsule, and the reverse turn of the chain and the methyl terminal in each polar region of the host. Guest exchange was slow on the NMR time scale, while tumbling was slow or close to the NMR time scale depending on the position and stereochemistry of the double bond. In contrast, the methyl esters were found to bind in three motifs depending on the position and stereochemistry of the double bond. Thus, the esters were observed to bind in a J-shaped, U-shaped (the turn in the guest occupying a polar region and the two termini competing for occupancy of the other pole), or a reverse J-shaped motif (ester moiety and turn each occupying a pole and the methyl terminal located near the equator). Relative binding constant (Krel) determinations revealed that the affinity for the capsule was dependent on the position and stereochemistry of the double bond.
- Wang, Kaiya,Gibb, Bruce C.
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p. 4279 - 4288
(2017/04/27)
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- Ralstonins A and B, Lipopeptides with Chlamydospore-Inducing and Phytotoxic Activities from the Plant Pathogen Ralstonia solanacearum
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Ralstonia solanacearum has an orphan hybrid polyketide synthase-nonribosomal peptide synthetase gene cluster. We herein isolate its products (named ralstonins A and B) from R. solanacearum and elucidate their structures and biological activities. Ralstonins are unusual lipodepsipeptides composed of 11 amino acids (containing unique amino acids such as β-hydroxytyrosine and dehydroalanine) and a 3-amino-2-hydroxyoctadecanoic acid, and their production is controlled by quorum sensing, a mechanism of bacterial cell-cell communication. Ralstonins exhibited chlamydospore-inducing activity and phytotoxicity.
- Murai, Yuta,Mori, Shoko,Konno, Hiroyuki,Hikichi, Yasufumi,Kai, Kenji
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supporting information
p. 4175 - 4178
(2017/08/23)
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- Biosynthesis-Assisted Structural Elucidation of the Bartolosides, Chlorinated Aromatic Glycolipids from Cyanobacteria
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The isolation of the bartolosides, unprecedented cyanobacterial glycolipids featuring aliphatic chains with chlorine substituents and C-glycosyl moieties, is reported. Their chlorinated dialkylresorcinol (DAR) core presented a major structural-elucidation challenge. To overcome this, we discovered the bartoloside (brt) biosynthetic gene cluster and linked it to the natural products through in vitro characterization of the DAR-forming ketosynthase and aromatase. Bioinformatic analysis also revealed a novel potential halogenase. Knowledge of the bartoloside biosynthesis constrained the DAR core structure by defining key pathway intermediates, ultimately allowing us to determine the full structures of the bartolosides. This work illustrates the power of genomics to enable the use of biosynthetic information for structure elucidation.
- Le?o, Pedro N.,Nakamura, Hitomi,Costa, Margarida,Pereira, Alban R.,Martins, Rosário,Vasconcelos, Vitor,Gerwick, William H.,Balskus, Emily P.
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supporting information
p. 11063 - 11067
(2016/07/06)
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- Synthesis and preferred conformations of all regio- and diastereoisomeric methyl 2,3-fluorohydroxyalkanoates
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Selective syntheses of enantiopure regio- and diastereomeric methyl 2,3-fluoro-hydroxyalkanoates via four different routes employing two types of fluorination reagents are reported. The anti- and syn-3-fluoro-2- hydroxyalkanoates 1 and 3 were prepared by treating the corresponding epoxides with Olah's reagent (Py·9HF). Cyclic sulfates prepared from the enantiomeric diols were ring-opened with TBAF to give the anti- and syn-2-fluoro-3-hydroxyalkanoates 2 and 4. Thestereochemical analysis was performed mainly by NMR spectroscopy. Applying DFT/B3LYP and SCS-MP2 quantum chemical methods, the coupling constants and relative energies of conformers were calculated. Solvent effects were considered using the COSMO continuum model. Regio- and stereoselective ring opening of enantio-pure epoxides or cyclic sulfates with pyridine·9HF or TBAF delivers anti- or syn-configurated 3-fluoro-2-hydroxy- or 2-fluoro-3-hydroxyalkanoates, respectively. The relative energies of conformers were calculated by quantum chemical methods. Those of 3-fluoro-2-hydroxy isomers are influenced by intramolecular O-H·O=C hydrogen bonds, while the regioisomers show close O-H·F-C contacts. Copyright
- Husstedt, Wibke S.,Wiehle, Susanne,Stillig, Christian,Bergander, Klaus,Grimme, Stefan,Haufe, Guenter
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body text
p. 355 - 363
(2011/02/28)
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- SINGLE-STAGE ESTERIFICATION OF OILS AND FATS
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A process for producing alkyl esters useful as biofuels and/or lubricants. An alkyl ester product produced by the process. The process comprises a single- stage reaction for esterifying a de-watered glyceride-containing feedstock with an anhydrous short chain alcohol in the presence of a basic esterification catalyst to produce a reaction product comprising alkyl esters and a reaction by-product comprising glycerol-containing substances and the catalyst-containing alcohol. The single-stage esterification reaction is conducted within a temperature and negative-pressure controllable vessel. The alkyl ester product is separated from the reaction by-product and may be further de-watered and/or purified. The catalyst-containing alcohol may be separated from the reaction by-product, de- watered and reused. The glycerol-containing substances may be separated from the reaction by-product and further purified. Useful glyceride-containing feedstocks include those prepared from plant or animal or fish materials, particularly those produced from seeds of mustard, canola, soybean, corn, cotton, flax and palm.
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Page/Page column 10-12
(2008/06/13)
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- (Z) 1'-propylbutyl 3-octadecenoate from Fagara budrunga fruits
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Chemical constituents of the Indian medicinal plant Fagara budrunga commonly known as mullilam, have been isolated. In addition to the known compounds a new ester has been obtained. It has been assigned the structure (Z) 1'-propylbutyl 3-octadecenoate 1 from chemical conversions and spectral analysis.
- Naik,Katke, Sujata,Banhatti, Padmini,Natu
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p. 122 - 124
(2007/10/03)
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- Process for the synthesis of α, β-unsaturated esters
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The present invention provides a process for the synthesis of an α,β-unsaturated ester from a mono-olefin-ester using Fe(CO)5.
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- Iron carbonyl-promoted isomerization of olefin esters to their α,β-unsaturated esters: Methyl oleate and other examples
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Ultraviolet photolysis of stoichiometric amounts of methyl oleate and Fe(CO)5 in hexanes solvent at 0°C gives Fe(CO)3(η4-α,β-ester) in which the α,β-unsaturated ester isomer of methyl oleate is stabilized by η4-oxadiene π coordination of the olefin and ester carbonyl groups to the Fe(CO)3 unit. Treatment of the Fe(CO)3(η4-α,β-ester) with pyridine or CO liberates the free α,β-ester, methyl octadec-trans-2-enoate, in 70% yield. The Fe(CO)3 unit both catalyzes the olefin isomerization and stabilizes the α,β-unsaturated ester, which results in the formation of the α,β-ester in a yield far above that (3.5%) observed for simple catalyzed methyl oleate isomerization. The much smaller olefin esters, methyl 3-butenoate and ethyl 4-methyl-4-pentenoate, are isomerized under the same conditions to their α,β-unsaturated esters in 94 and 90% yields, respectively. The effects of reaction conditions on the yield, the use of Fe(CO)3(cis-cyclooctene)2 as a nonphotolytic catalyst, and the mechanism of this useful synthetic process are discussed.
- Shih, Kuo-Chen,Angelici, Robert J.
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p. 7784 - 7792
(2007/10/03)
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