- New sustainable synthetic routes to cyclic oxyterpenes using the ecocatalyst toolbox
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Cyclic oxyterpenes are natural products that are mostly used as fragrances, flavours and drugs by the cosmetic, food and pharmaceutical industries. However, only a few cyclic oxyterpenes are accessible via chemical syntheses, which are far from being ecofriendly. We report here the synthesis of six cyclic oxyterpenes derived from ?-pinene while respecting the principles of green and sustainable chemistry. Only natural or biosourced catalysts were used in mild conditions that were optimised for each synthesis. A new generation of ecocatalysts, derived from Mn-rich water lettuce, was prepared via green processes, characterised by MP-AES, XRPD and TEM analyses, and tested in catalysis. The epoxidation of ?-pinene led to the platform molecule, ?-pinene oxide, with a good yield, illustrating the efficacy of the new generation of ecocatalysts. The opening ?-pinene oxide was investigated in green conditions and led to new and regioselective syntheses of myrtenol, 7-hydroxy-α-terpineol and perillyl alcohol. Successive oxidations of perillyl alcohol could be performed using no hazardous oxidant and were controlled using the new generation of ecocatalysts generating perillaldehyde and cuminaldehyde.
- Bihanic, Camille,Grison, Claude,Lasbleiz, Arthur,Le Blainvaux, Pierre,Petit, Eddy,Regnier, Morgan
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- Preparation of α-terpineol and perillyl alcohol using zeolites beta
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The preparation of α-terpineol by direct hydration of limonene catalyzed by zeolites beta was studied. The same catalyst was used to prepare perillyl alcohol by isomerization of β-pinene oxide in the presence of water. The aim was to optimize the reaction conditions to achieve high conversions of starting material and high selectivity to the desired products. In the case of limonene, it was found that the highest selectivity to α-terpineol was 88% with conversion of 36% under the conditions: 50?wt% of catalyst beta 25, 10% aqueous acetic acid (10?mL) (volume ratio limonene:H2O = 1:4.5), temperature 50?°C, after 24?h. In the case of β-pinene oxide, it was found that the highest selectivity to perillyl alcohol, which was 36% at total conversion, was obtained in the reaction under the following conditions: dimethyl?sulfoxide as solvent (volume ratio β-pinene oxide:DMSO = 1:5), catalyst beta 25 without calcination (15?wt%), demineralized water (molar ratio β-pinene oxide:H2O = 1:8), temperature 70?°C, 3?h. The present study shows that the studied reactions are suitable for the selective preparation of chosen compounds.
- ?erveny, Libor,Vysko?ilová, Eli?ka,Zítová, Kate?ina
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p. 4297 - 4310
(2021/07/26)
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- Selective Catalytic Isomerization of β-Pinene Oxide to Perillyl Alcohol Enhanced by Protic Tetraimidazolium Nitrate
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A series of tetraimidazolium salts with different anions was prepared and applied in the isomerization of β-pinene oxide. After examining the activity of different catalysts, a remarkable enhancement of the selectivity of perillyl alcohol (47 %) was obtained over [PEimi][HNO3]4 under mild reaction conditions and using DMSO as the solvent. Furthermore, noncovalent interactions between solvent molecules and the catalyst were found by FT-IR spectroscopy and confirmed by computational chemistry. The homogeneous catalyst showed excellent stability and was reused up to six times without significant loss.
- Li, Hui,Liu, Jian,Zhao, Juan,He, Huiting,Jiang, Dabo,Kirk, Steven Robert,Xu, Qiong,Liu, Xianxiang,Yin, Dulin
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p. 477 - 485
(2021/05/04)
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- Kinetics of the Aqueous Phase Reactions of Atmospherically Relevant Monoterpene Epoxides
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Laboratory and field measurements have demonstrated that an isoprene-derived epoxide intermediate (IEPOX) is the origin of a wide range of chemical species found in ambient secondary organic aerosol (SOA). In order to explore the potential relevance of a similar mechanism for the formation of monoterpene-derived SOA, nuclear magnetic resonance techniques were used to study kinetics and reaction products of the aqueous-phase reactions of several monoterpene epoxides: β-pinene oxide, limonene oxide, and limonene dioxide. The present results, combined with a previous study of α-pinene oxide, indicate that all of these epoxides will react more quickly than IEPOX with aqueous atmospheric particles, even under low-acidity conditions. As for α-pinene oxide, the observed products can be mainly rationalized with a hydrolysis mechanism, and no long-lived organosulfate or nitrate species nor species that retain the β-pinene bicyclic carbon backbone are observed. As bicyclic ring-retaining organosulfate and nitrate species have been previously observed in monoterpene-derived SOA, it appears that monoterpene-derived epoxides may not be as versatile as IEPOX in producing a range of SOA species, and other mechanisms are needed to rationalize organosulfate and nitrate formation.
- Cortés, DIego A.,Elrod, Matthew J.
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p. 9297 - 9305
(2017/12/18)
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- Iron-catalyzed epoxidation of aromatic olefins and 1,3-dienes
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The combination of iron(III) chloride, pyridine-2,6-dicarboxylic acid and formamidine ligands allows for the epoxidation of styrenes and conjugated dienes in excellent chemoselectivity and yields.
- Schroeder, Kristin,Enthaler, Stephan,Join, Benoit,Junge, Kathrin,Beller, Matthias
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scheme or table
p. 1771 - 1778
(2010/09/11)
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- Design of a bio-inspired imidazole-based iron catalyst for epoxidation of olefins: Mechanistic insights
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A novel defined iron catalyst for the epoxidation of aromatic and aliphatic olefins with hydrogen peroxide as the terminal oxidant is described. Our catalyst approach is based on bio-inspired both alkyl- and aryl-substituted imidazoles in combination with cheap and abundant iron trichloride hexahydrate. Heterocycles similar to imidazole can be used as ligands in this epoxidation system, too. The novel system is stable towards air and water. It is shown that the mechanism depends strongly on the used ligands and substrates. In the presence of radical scavengers no carbon-centered radical could be detected.
- Schr?der, Kristin,Junge, Kathrin,Spannenberg, Anke,Beller, Matthias
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experimental part
p. 364 - 370
(2011/01/04)
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- Chemistry Around δ-Terpineol
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Bromination, hydroboration, epoxidation, 1,2-dihydroxylation and acidification reactions upon δ-terpineol are described.
- Bull, Steven D.,Carman, Raymond M.
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p. 1869 - 1880
(2007/10/02)
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- 7-Hydroxy-1,8-cineole and 7-Cineolic Acid. Two New Possum Urinary Metabolites
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7-Hydroxy-1,8-cineole (3a) and the corresponding carboxylic acid (3b) have been isolated from the urine of brushtail possums (Trichosurus vulpecula: Marsupialia) fed a diet enhanced with 1,8-cineole.Chemical syntheses of these two novel metabolites are described.
- Bull, Steven D.,Carman, Raymond M.,Carrick, Frank N.,Klika, Karel D.
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p. 441 - 447
(2007/10/02)
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- THE STEREOSPECIFIC HYDROXILATION OF ENDOCYCLIC ETHYLENIC LINKAGE IN THE BIOTRANSFORMATION OF α- TERPINYL ACETATE WITH CULTURED SUSPENSION CELLS OF NICOTIANA TABACUM
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The biotransformation of (+/-)-8-acetoxy-p-menth-1-ene (α-terpinyl acetate) with the cultured cells of Nicotiana tabacum was found to result in the predominant formation of 8-acetoxy-c-4-p-menthane-r-1, t-2-diol.This experimental result indicates that the hydroxylation of the endocyclic ethylenic linkage with the cultured suspension cells is stereospecific.
- Hirata, Toshifumi,Lee, Ym Sook,Suga, Takayuki
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p. 671 - 674
(2007/10/02)
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