- First total synthesis of paracaseolide A
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The first total synthesis of the paracaseolide A, a very unusual tetraquinane oxa-cage bislactone recently isolated from the mangrove Sonneratia paracaseolaris, has been achieved. The final step and culmination of the eight-step synthetic sequence is a [4 + 2] dimerization of a 4-hydroxybutenolide, generated by singlet oxygen-mediated oxidation of a furan precursor.
- Noutsias, Dimitris,Vassilikogiannakis, Georgios
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- Facile synthesis of plasmalogens via barbier-type reactions of vinyl dioxanes and vinyl dioxolanes with alkyl halides in LiDBB solution
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Plasmalogens (i.e. plasmenylcholines or plasmenylethanolamines) are a biologically important class of glycerophospholipids that have been difficult to synthesize due to the presence of an acid and oxidatively labile (Z)-vinyl ether substituent at the sn-1 position and a base-labile sn-2 acyl substituent that easily migrates during silica gel purification. We report two facile synthetic methods for the preparation of racemic plasmenylcholines via a tandem reductive vinyl dioxane/dioxolane ring opening and alkyliodide coupling process that proceeds in a single pot reaction. The key step in the formation of (Z)-vinyl ether precursors for the production of plasmenylcholines is accomplished using LiDBB under Barbier-type conditions to give the corresponding TBDMS-protected 1-O-Z′-vinylglycerol intermediate in moderate yields. This pathway is the most direct synthetic route for the formation of plasmenylcholines to date, requiring a total of six transformations from acrolein and glycerol or solketal as inexpensive starting materials, to generate glycerophosphocholine-type plasmalogens in 4% overall yield.
- Shin, Junhwa,Gerasimov, Oleg,Thompson, David H.
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- METHODS FOR THE SYNTHESIS OF PLASMALOGENS AND PLASMALOGEN DERIVATIVES, AND THERAPEUTIC USES THEREOF
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A method for preparing plasmalogens and derivatives thereof represented by Formula B, wherein R1 and R2 are similar or different, derived from fatty acids; R3 is selected from hydrogen and small alkyl groups. The synthetic route involves production of novel cyclic plasmalogen precursors of Formula A and their conversion to plasmalogens and plasmalogen derivatives of Formula B. Also disclosed is the therapeutic use of plasmalogens and derivatives thereof as produced by the synthetic route of the present invention.
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Page/Page column 24-25
(2013/06/05)
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- In vivo studies of dialkynoyl analogues of DOTAP demonstrate improved gene transfer efficiency of cationic liposomes in mouse lung
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A novel set of dialkynoyl analogues of the cationic, gene delivery lipid DOTAP (1) was synthesized. Structure-activity studies demonstrate that replacement of the cis-double bonds of DOTAP with triple bonds in varying positions alters both the physical properties of the resultant cationic liposome-DNA complexes and their biological functionalities, both in vitro and in vivo. Particularly, in vivo studies demonstrate that pDNA transfection of mouse lung endothelial cells with lead analogue DS(14-yne)TAP (4):cholesterol lipoplexes exhibits double the transfection level with less associated toxicity relative to the well-established DOTAP:cholesterol system. In fact, 4:cholesterol delivers up to 3 times the dose of pDNA in mice than can be tolerated by DOTAP, leading to nearly 3 times greater marker-gene expression. X-ray diffraction studies suggest that lipoplexes containing analogue 4 display increased stability at physiological temperatures. Our results thus suggest that analogue 4 is a potentially strong candidate for the gene therapy of lung tumors.
- Fletcher, Steven,Ahmad, Ayesha,Perouzel, Eric,Heron, Andrew,Miller, Andrew D.,Jorgensen, Michael R.
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p. 349 - 357
(2007/10/03)
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- A dialkynoyl analogue of DOPE improves gene transfer of lower-charged, cationic lipoplexes
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Positively-charged gene delivery agents, such as cationic liposomes, typically prepared by mixing a cationic lipid and a neutral lipid in a 1: 1 molar ratio, exhibit a fundamental flaw: on the one hand, the charge encourages cell uptake; on the other hand, the charge leads to aggregation in vivo with anionic serum components. We herein report a more phase-stable analogue of the zwitterionic and fusogenic lipid DOPE that allows for the reduction of the cationic lipid component of the liposome from 50 to 9 mol% with almost no apparent loss in transfection activity. This reduction in charge may induce important in vivo stability whilst still imparting high cell uptake and transgene expression. The Royal Society of Chemistry 2006.
- Fletcher, Steven,Ahmad, Ayesha,Perouzel, Eric,Jorgensen, Michael R.,Miller, Andrew D.
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p. 196 - 199
(2007/10/03)
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- Structure based interference with insect behaviour - Cyclopropene analogues of pheromones containing Z-alkenes
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Analogues of the pheromones of three insect species (Musca domestica L., Plutella xylostella L. and Ephestia elutella Hbn.) in which a Z-alkene has been replaced by a 1,2-disubstituted cyclopropene have been synthesized. The analogues interfere with normal mating behaviour for each species.
- Al Dulayymi, Juma'a R.,Baird, Mark S.,Simpson, Michael J.,Nyman, Susan,Port, Gordon R.
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p. 12509 - 12520
(2007/10/03)
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- Functionalized Ethylene Oligomers as Phase-Transfer Catalysts
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Ethylene oligomers with Mv in the range 1000-3000 containing terminal groups such as crown ethers, azacrown ethers, and phosphonium salts have been prepared and used as phase-transfer catalysts.These oligomeric catalysts have solubility properties similar to polyethylene in that they are insoluble at 25 deg C but dissolve in organic solutions at elevated (90-110 deg C) temperatures.Such oligomeric phase-transfer catalysts have activities comparable to their low molecular wait congeners and to activities reported for insoluble polystyrene-bound phase-transfer catalysts.After these oligomeric catalysts have been used in a reaction at 100 deg C, thay can be readily separated from the reaction products by cooling to form a precipitate, which can be isolated by filtration.Such catalysts may be reused without loss of activity.These catalysts are also effective in "solid-liquid" phase-transfer reactions in which an inorganic solid is suspended in a hot organic solution containing catalyst and substrate.
- Bergbreiter, David E.,Blanton, J. R.
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p. 5828 - 5833
(2007/10/02)
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