- Sustainable catalytic protocols for the solvent free epoxidation and: Anti -dihydroxylation of the alkene bonds of biorenewable terpene feedstocks using H2O2 as oxidant
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A tungsten-based polyoxometalate catalyst employing aqueous H2O2 as a benign oxidant has been used for the solvent free catalytic epoxidation of the trisubstituted alkene bonds of a wide range of biorenewable terpene substrates. This epoxidation protocol has been scaled up to produce limonene oxide, 3-carene oxide and α-pinene oxide on a multigram scale, with the catalyst being recycled three times to produce 3-carene oxide. Epoxidation of the less reactive disubstituted alkene bonds of terpene substrates could be achieved by carrying out catalytic epoxidation reactions at 50 °C. Methods have been developed that enable direct epoxidation of untreated crude sulfate turpentine to afford 3-carene oxide, α-pinene oxide and β-pinene oxide. Treatment of crude epoxide products (no work-up) with a heterogeneous acid catalyst (Amberlyst-15) results in clean epoxide hydrolysis to afford their corresponding terpene-anti-diols in good yields.
- Cunningham, William B.,Tibbetts, Joshua D.,Hutchby, Marc,Maltby, Katarzyna A.,Davidson, Matthew G.,Hintermair, Ulrich,Plucinski, Pawel,Bull, Steven D.
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supporting information
p. 513 - 524
(2020/02/13)
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- COMPOUNDS AND METHODS OF TREATING OCULAR DISORDERS
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A method of treating an ocular disorder in a subject associated with increased all-trans-retinal in an ocular tissue includes administering to the subject a therapeutically effective amount of a primary amine compound of formula (I); and pharmaceutically acceptable salts thereof.
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- MnO2/TBHP: A Versatile and User-Friendly Combination of Reagents for the Oxidation of Allylic and Benzylic Methylene Functional Groups
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In the presence of activated MnO2, tert-butyl hydroperoxide (TBHP) in CH2Cl2 is able to oxidize the allylic and benzylic methylene groups of different classes of compounds. I describe a one-pot oxidation protocol based on two sequential steps. In the first step, carried out at low temperature, MnO2 catalyses the oxidation of the methylene group. This is followed by a second step where reaction temperature is increased, allowing MnO2 both to catalyse the decomposition of unreacted TBHP and to oxidize allylic alcohols that could possibly be formed. The proposed oxidation procedure is generally applicable, although its efficiency, regioselectivity, and chemoselectivity are strongly dependent on the structure of the substrate. A simple and user-friendly synthetic procedure for the oxidation of allylic and benzylic methylene groups to the corresponding conjugated carbonyl derivatives is described. The proposed oxidation protocol is based on the combined use of MnO2 and tert-butyl hydroperoxide, and is generally applicable.
- Serra, Stefano
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p. 6472 - 6478
(2015/10/19)
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- Synthesis, structural characterization and effect on human granulocyte intracellular cAMP levels of abscisic acid analogs
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The phytohormone abscisic acid (ABA), in addition to regulating physiological functions in plants, is also produced and released by several mammalian cell types, including human granulocytes, where it stimulates innate immune functions via an increase of the intracellular cAMP concentration ([cAMP]i). We synthesized several ABA analogs and evaluated the structure-activity relationship, by the systematical modification of selected regions of these analogs. The resulting molecules were tested for their ability to inhibit the ABA-induced increase of [cAMP]i in human granulocytes. The analogs with modified configurations at C-2′ and C-3′ abrogated the ABA-induced increase of the [cAMP]i and also inhibited several pro-inflammatory effects induced by exogenous ABA on granulocytes and monocytes. Accordingly, these analogs could be suitable as novel putative anti-inflammatory compounds.
- Bellotti, Marta,Salis, Annalisa,Grozio, Alessia,Damonte, Gianluca,Vigliarolo, Tiziana,Galatini, Andrea,Zocchi, Elena,Benatti, Umberto,Millo, Enrico
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- Selective oxidation reactions of natural compounds with hydrogen peroxide mediated by methyltrioxorhenium
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We have investigated the oxidative behaviour of natural compounds such as methyl abietate (1), farnesyl acetate (2), a-ionone (3), β-ionone (4), methyl linolelaidate (5), methyl linolenate (6) and bergamottin (7) with the oxidant system methyltrioxo-rhenium/ H2O2/pyridine. The reactions, performed in CH2Cl2/H2O at 25 °C, have shown good regioand stereoselectivity. The oxidation products were isolated by HPLC or silica gel chromatography and characterized by MS(EI), 1H-, 13C-NMR, APT, gCOSY, HSQC, TOCSY and NOESY measurements. The selectivity seems to be controlled by the nucleophilicity of double bonds and by stereoelectronic and steric effects.
- Amato, Maria E.,Ballistreri, Francesco P.,Pappalardo, Andrea,Tomaselli, Gaetano A.,Toscano, Rosa M.,Sfrazzetto, Giuseppe Trusso
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p. 13754 - 13763
(2014/01/06)
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- Epoxidation of olefins by β-bromoalkoxydimethylsulfonium ylides
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Olefins can be converted to their respective epoxides in a one-pot procedure by dissolving the olefin in anhydrous DMSO, adding NBS to the reaction mixture to generate a β-bromoalkoxydimethylsulfonium ylide, and then adding DBU to the reaction mixture. A large variety of alkenes were successfully epoxi-dized with yields largely dependent on the structure of the alkene. Most importantly, the facial selectivity of this one-pot process is the opposite of that observed when using traditional epoxidizing reagents. Electron-poor alkenes are not epoxidized under these conditions.
- Majetich, George,Shimkus, Joel,Li, Yang
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supporting information; experimental part
p. 6830 - 6834
(2011/03/18)
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- Lipase-mediated synthesis of the enantiomeric forms of 4,5-epoxy4,5-dihydro-α-ionone, and 5,6-epoxy-5,6-dihydro-β-ionone. A new direct access to enantiopure (R)-, and (5)-α-ionone
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Stereoselective lipase-mediated esterifications of epoxy-a-ionpl 5, and epoxy-ionol 9 afTorded suitable precursors of the enantiomers of the corresponding oxidised derivatives epoxy-u-ionone 3, and epoxy-ionone 4. An interesting development of this work is the easy conversion of enantiopure 3a, and 3b into highly valuable enantiopure (5)-, and (R)-ionone (1a, and Ib) via a mild deoxygenation reaction.
- Aleu, Josefina,Brcnna, Elisabctta,Fuganti, Claudio,Serra, Stefano
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p. 271 - 278
(2007/10/03)
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- A synthetic approach to (+/-)-forskolin. Part I. Preparation of key hydrobenzofuran intermediates
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In a synthetic approach to (+/-)-forskolin 1, a stereoselective preparation of the unsaturated lactone 2 was envisaged.Propargylic derivatives 18a-c were prepared from available α-ionone 5 and treated with Bu3SnH/AIBN to give the bicyclic vinylstannanes 19a-c in high yield.From these compounds we then performed transmetallation reactions to obtain the 21a-c and 22b homologous derivatives.The two enyne compounds 29 and 30 were then prepared by our previous approach to lactone 2 involving a radical C7-C8 bond formation.In a second radical approach promoted by SmI2, the diol 10, was used to synthesize a potential precursor of the dialdehyde 9. - Keywords: forskolin; tributylstannane; radical cyclization; transmetallation; vinylstannane; vinyl iodide; Pd(0) coupling reaction
- Anies, Claude,Pancrazi, Ange,Lallemand, Jean-Yves
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p. 183 - 202
(2007/10/03)
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- REACTIONS OF α-IONONE OXIDE WITH AMINIUM SALTS, BROENSTED AND LEWIS ACIDS. SYNTHESIS OF NEW TERMINAL GROUP SYNTHONS
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Catalytic amounts of aminium salts induce the isomerization of α-ionone oxide, 5, affording 1,3,3-trimethyl-2-(3-oxo-1-buten-1-yl)cyclopent-1-ylcarbaldehydes, 6a,b together with trace amounts of 2,4,4-trimethyl-3-(3-oxo-1-buten-1-yl)cyclohexanones 6c,d.Pr
- Lopez, Luigi,Mele, Giuseppe,Paradiso, Vincenza,Nacci, Angelo,Mastrorilli, Piero
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p. 725 - 728
(2007/10/03)
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- Optisch aktive 4,5-Epoxy-4,5-dihydro-α-ionone und Synthese der stereoisomeren 4,5:4',5'-Diepoxy-4,5,4',5'-tetrahydro-ε,ε-carotine und der sterische Verlauf ihrer Hydrolyse
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We prove that epoxidation with peracid of α-ionone, contrary to a recently published statement, predominantly leads to the cis-epoxide.Acid hydrolysis affords a single 4,5-glycol whose structure, established by an X-ray analysis, shows that oxirane opening occured with inversion at the least substituted position (C(4)).Stable cis- and trans-epoxides are prepared by epoxidation of the C15-phosphonates derived from α-ionone.Both the racemic and optically active form are used for the synthesis of the 4,5:4',5'-diepoxy-4,5,4',5'-tetrahydro-ε,ε-carotenes having the following configuration in the end goups: meso-cis/cis, meso-trans/trans, rac-cis/trans, rac- and (6R,6'R)-cis/cis, rac- and (6R,6'R)-trans/trans, rac- and (6R,6'R)-cis/trans, and (6R,6'R)-cis/ε.Acid hydrolysis of the cis/cis-epoxycarotenoids under relatively strong conditions occurs again with inversion at C(4)/C(4') in case of the cis/cis-epoxycarotenoids, but at C(5)/C(5') in case of the trans/trans-epoxycarotenoids.An independent synthesis of this 4,5,4',5'-tetrahydro-ε,ε-carotene-4,5,4',5'-tetrol is presented.The irregular results of the oxirane hydrolysis are explained by assumption of neighbouring effects of the lateral chain. 400-MHz-1H-NMR data are given for each of the stereoisomeric sets.In the visible range of the CD spectra, the (6R,6R')-epoxycarotenoids compared with (6R,6R')-ε,ε-carotene exhibit an inversion of the Cotton effects.
- Uebelhart, Peter,Baumeier, Andreas,Haag, Andreas,Prewo, Roland,Bieri, Jost Hans,Eugster, Conrad Hans
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p. 816 - 834
(2007/10/02)
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- An Intramolecular Diels-Alder Strategy to Forskolin
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A strategy for the construction of the AB ring system of forskolin based on a novel intramolecular Diels-Alder reaction is reported.
- Nicolaou, K. C.,Li, Wen Sen
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