- Phosphonium-based ionic liquids: Economic and efficient catalysts for the solvent-free cycloaddition of CO2 to epoxidized soybean vegetable oil to obtain potential bio-based polymers precursors
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A series of phosphonium-based ionic liquids have been prepared in one step in a simple way from inexpensive feedstocks. The prepared ionic liquids have been successfully tested as catalysts in the solvent-free cycloaddition reaction of CO2 to an epoxidized soybean oil to obtain carbonated soybean oil that can be potentially employed as bio-monomer in the synthesis for bio-based polymers. The catalytic performance of these ionic liquids was compared to the widely used and benchmark catalyst in CO2 cycloaddition to epoxides reaction, namely tetrabutylammonium bromide at different reaction conditions. The influence of some reaction parameters such as temperature, CO2 pressure, reaction time and catalyst amount was studied. It has been found that the solubility of the prepared ionic liquids in the reaction media (epoxidized soybean oil) is a key factor that limits the catalytic performance of some of the synthesized ionic liquids. All prepared ionic liquids have shown higher thermal stability that the benchmark catalyst and three of them have shown superior catalytic performance. The best results in terms of conversion and selectivity have been obtained with dodecyltriphenylphosphonium bromide (5) achieving almost full conversion (99.8%) and excellent selectivity (84.0%) after 5 h reaction at 160 oC and 40 bar of CO2. Outstanding results compared to those reported in the literature with similar catalysts in the solvent-free CO2 cycloaddtion to an epoxidized soybean oil to obtain the corresponding carbonated oil have been achieved. Considering the facile synthesis of catalyst 5, the large availability and non-expensive of the feedstocks and its catalytic performance it can be considered a valuable and green alternative for CO2 fixation to epoxidized vegetable oil.
- Centeno-Pedrazo, A.,Freixa, Z.,Garcia-Suarez, E. J.,Perez-Arce, J.,Prieto-Fernandez, S.
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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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- Synthesis and inhibitory activities against colon cancer cell growth and proteasome of alkylresorcinols
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We have identified alkylresorcinols (ARs) as the major active components in wheat bran against human colon cancer cell growth (HCT-116 and HT-29) using a bioassay-guided approach. To further study the structure-activity relationships, 15 ARs and their intermediates (1-15) were synthesized expediently by the modified Wittig reaction in aqueous media, and six 5-alkylpyrogallols and their analogues (16-21) were prepared by the general Grignard reaction. The synthetic AR analogues were evaluated for activities against the growth of human colon cancer cells HCT-116 and HT-29 and the chymotrypsin-like activity of the human 20S proteasome. Our results found that (1) AR C13:0 and C15:0 (13 and 14) had the greatest inhibitory effects in human colon cancer cells HCT-116 and HT-29, while decreasing or increasing the side chain lengths diminished the activities; (2) two free meta-hydroxyl groups at C-1 and C-3 on the aromatic ring of the AR analogues greatly contributed to their antitumor activity; (3) the introduction of a third hydroxyl group at C-2 (20 and 21) into the aromatic ring of the AR analogues yielded no significant enhancement in activity against HCT-116 cells and decimated the effects against HT-29 cells, but dramatically increased the activity against the chymotrypsin-like activity of the human 20S proteasome; and (4) AR C11:0 (12) was found to have the greatest effect in a series of AR C9:0-C17:0 against the chymotrypsin-like activity of the human 20S proteasome.
- Zhu, Yingdong,Soroka, Dominique N.,Sang, Shengmin
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p. 8624 - 8631
(2012/11/13)
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- An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens
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The first synthesis of bioactive long alkyl chain 5-n-alkylresorcinols, present in whole grain products, by a novel modification of the Wittig reaction is described. All the main long chain 5-n-alkylresorcinols present in rye and wheat, including C23 and C25 analogues and haptens, which have not been previously prepared, were synthesised. Microwave-promoted reactions of a semistabilized ylid and alkanals in water gave good yields in both pressurized and open systems. An alternative microwave-promoted synthesis starting from non-stabilized alkyltriphenylphosphonium salts and 3,5-dimethoxybenzaldehyde worked as well. Aqueous media were suitable for the reactions even if the starting materials were not soluble in water. The 5-n-alkylresorcinols are potential biomarkers of whole grain intake, and the new hapten derivatives of 5-n-alkylresorcinols will open the way for the immunochemical detection techniques of alkylresorcinols.
- Parikka, Kirsti,Waehaelae, Kristiina
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supporting information; experimental part
(2010/04/22)
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- Close-range attraction in Lygocoris pabulinus (L.)
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Males of the green capsid bug, Lygocoris pabulinus, exhibit a specific courtship behavior, i.e., a vibration of the abdomen. When both live and dead females were offered to males, this vibration behavior was elicited in most of the males tested. When females were dissected into separate body parts, heads, wings, and legs elicited equal responses, while thorax plus abdomen elicited a much lower response. When separate body parts were extracted, the leg extracts elicited significantly stronger responses than any other extract. This suggests that female L. pabulinus legs are either the source of a close-range sex pheromone or that pheromone is accumulated on the legs due to grooming behavior. The leg extracts contained several hydrocarbons such as n-alkenes, n-alkanes, and some methylalkanes. Female extracts contained more (Z)-9-pentacosene and male extracts contained more (Z)-9-heptacosene. Substrates on which females had walked elicited similar responses as female legs, indicating that the pheromone is deposited on the substrate. This enlarges the functional range of low-volatility compounds, which are thought to function only when sexes are in close vicinity or in contact.
- Drijfhout, Falko P.,Groot, Astrid T.
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p. 1133 - 1149
(2007/10/03)
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- A CONVENIENT SYNTHESIS OF LONG-CHAIN 3-n-ALKYLTHIOPHENES AND 3-n-ALKYLFURANS
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The syntheses of 3-substituted long-chain furans and thiophenes by a Wittig reaction are described. 1H-NMR and UV data of these compounds are reported.
- Shabana, R.,Amer, Adel,Mark, H. B.,Zimmer, Hans
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p. 299 - 306
(2007/10/02)
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- SYNTHESIS OF (-)-DIHYDROMAHUBANOLIDE B AND (-)-ISODIHYDROMAHUBANOLIDE B
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The total synthesis of (-)-dihydromahubanolide B and (-)-isodihydromahubanolide B isolated from the Amazonian Lauraceae Licaria mahuba (Samp.) Kosterm was achieved starting from (-)-methyl 5-hydroxymethyl-2,2-dimethyl-1,3-dioxolane-4-carboxylate which was readily available from L-(+)-tartaric acid.
- Tanaka, Akira,Yamashita, Kyohei
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p. 319 - 322
(2007/10/02)
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