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| 2. |
- Cosner, Casey C., et al.
(författare)
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Evolution of Concise and Flexible Synthetic Strategies for Trichostatic Acid and the Potent Histone Deacetylase Inhibitor Trichostatin A
- 2013
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; :1, s. 162-172
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Tidskriftsartikel (refereegranskat)abstract
- (R)-(+)-Trichostatic acid and (R)-(+)-trichostatin A (TSA) are natural products that have attracted considerable attention in the field of epigenetic therapies. TSA in particular is a naturally occurring hydroxamic acid having potent activity as a histone deacetylase inhibitor (HDACi) and having significant potential for treatment of a myriad of genetically based diseases. Development of TSA and other trichostatic acid derivatives into useful small-molecule therapies has been hindered by the low natural abundance and high cost associated with these compounds. We report herein our collective efforts towards the development of concise and scalable routes for the synthesis of trichostatic acid and TSA in both racemic and enantioenriched forms. Three independent synthetic pathways were developed with varying degrees of efficiency and convergency. In the first synthesis, the key step was a vinylogous Horner-Wadsworth-Emmons condensation. A Marshall propargylation reaction was used as the key step in the second synthesis, and Pd-catalyzed a-alkenylation of a ketone zinc enolate by using various functionalized alkenyl or dienyl halides was developed for the third synthesis. The second pathway proved to be readily amenable to an enantioselective modification, and both the second and third pathways were straightforwardly adapted for the facile preparation of new analogues of trichostatic acid and TSA.
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| 3. |
- Di Francesco, Davide, et al.
(författare)
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Debottlenecking a Pulp Mill by Producing Biofuels from Black Liquor in Three Steps
- 2021
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:11, s. 2414-2425
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Tidskriftsartikel (refereegranskat)abstract
- By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO2 and H2SO4 respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2 : 1 : 0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.
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| 4. |
- Dorange, Ismet, et al.
(författare)
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Allenes as carbon nucleophiles in intramolecular attack on (pi-1,3-diene)palladium complexes : Evidence for trans carbopalladation of the 1,3-diene
- 2003
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 9:14, s. 3445-3449
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Tidskriftsartikel (refereegranskat)abstract
- Reaction of allene-substituted cyclohexa- and cyclohepta-1,3-dienes with [PdCl2(PhCN)(2)] gave eta(3)-( 1,2,3)-cyclohexenyl- and eta(3)-(1,2,3)-cycloheptenylpalladium complexes. respectively. in which C-C bond formation between the allene and the 1.3-diene has occurred. Analysis of the (pi-allyl)palladium complexes by NMR spectroscopy. using reporter ligands, shows that the C-C bond formation has occurred by a trans carbopalladation involving nucleophilic attack by the middle carbon atom of the allene on a (pi-diene)palladium(n) complex. The stereochemistry of the (pi-allyl)palladium complexes was confirmed by benzoquinone-induced stereoselective transformations to allylic acetates.
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| 7. |
- Franzén, Johan, et al.
(författare)
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Stereoselective palladium-catalyzed carbocyclization of allenic allylic carboxylates
- 2003
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 125:46, s. 14140-14148
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Tidskriftsartikel (refereegranskat)abstract
- Palladium(0)-catalyzed reaction of allene-substituted allylic carboxylates 3-8 employing 2-5 mol % of Pd(dba)(2) in refluxing toluene leads to the carbocyclization and elimination of carboxylic acid to give bicyclo[4.3.0]nonadiene and bicyclo[5.3.0]decadiene derivatives (12-17). The carbon-carbon bond formation is stereospecific, occurring syn with respect to the leaving group. Addition of maleic anhydride as a ligand to the above-mentioned procedures changed the outcome of the reaction, and under these conditions 3-5 afforded cycloisomerized products 21-23. The experimental results are consistent with a mechanism involving oxidative addition of the allylic carboxylate to Pd(0) to give an electron-deficient (pi-allyl)palladium intermediate, followed by nucleophilic attack by the allene on the face of the pi-allyl opposite to that of the palladium atom. Furthermore, it was found that the Pd(dba)(2)-catalyzed cyclization of the trans-cycloheptene derivative (trans-8) can be directed to give either the trans-fused (trans-17) or the cis-fused (cis-17) ring system by altering the solvent. The former reaction proceeds via a nucleophilic trans-allene attack on the (pi-allyl)palladium intermediate, whereas the latter involves a syn-allene insertion into the allyl-Pd bond of the same intermediate. The products from the carbocylization undergo stereoselective Diels-Alder reactions to give stereodefined polycyclic systems in high yields.
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| 9. |
- Hedenström, Erik, et al.
(författare)
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Stereoisomeric analysis of 6,10,14-Trimethylpentadecan-2-ol and the corresponding ketone in wing extracts from African Bicyclus butterfly species
- 2015
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 1573-1561 .- 0098-0331. ; 41:1, s. 44-51
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Tidskriftsartikel (refereegranskat)abstract
- Gas chromatography (GC) and mass spectrometry (MS) were used to determine the stereoisomeric compositions of 6,10,14-trimethylpentadecan-2-ol and 6,10,14-trimethylpentadecan-2-one in wing extracts from 17 Bicyclus butterfly species from different regions of Africa. All samples were purified using solid phase extraction (SPE). Since some species contained both alcohol and ketone, these were separated and the ketone was reduced to the alcohol before analysis as either (R)-trans-chrysanthemoyl or (S)-2-acetoxypropionyl esters. A novel asymmetric synthesis was developed for a reference mixture of (2R/S,6S,10R)-6,10,14-trimethylpentadecan-2-ol with known composition of the eight stereoisomers. The mixture then was used as the (R)-trans-chrysanthemoyl esters to correlate each of the eight gas chromatographic peaks to a specific stereoisomer of the extracted wing compounds. Seven butterfly species showed (2R,6R,10R)-configuration of the alcohol, four species contained minute amounts of alcohol too small to determine the stereochemistry, nine species showed (6R,10R)-configuration of the ketone, and one species contained minute amounts of ketone too small to determine the stereochemistry. No other stereoisomers of alcohol or ketone could be detected in the extracts, and the quantities of the compounds in the wing extracts varied from 5 to 900 ng per sample for each species.
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| 10. |
- Löfstedt, Joakim, et al.
(författare)
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Carbon-carbon bond formation in regio- and stereoselective palladium-catalyzed cyclization of allene-substituted conjugated dienes
- 2001
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 66:24, s. 8015-8025
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Tidskriftsartikel (refereegranskat)abstract
- Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic transformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.
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