- 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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- Practical synthesis of canthaxanthin
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In this study, a novel route for the total synthesis of canthaxanthin is described. The synthesis is firstly based on an epoxidation of α-ionone with metachloroperbenzoic acid to afford the epoxide, followed by conversion of the epoxide to 3-hydroxyl-β-ionone in the presence of sodium methoxide. Next, 3-hydroxyl-C14-aldehyde was obtained by a Darzens condensation with 4-hydroxyl-β-ionone and methyl chloroacetate, which can be converted to 3-hydroxyl-C15-phophonate via a Wittig–Horner condensation with tetraethyl methylenebisphosphonate. Then, a Wittig–Horner condensation with 3-hydroxyl-C15-phosphonate and C10-trienedial resulted in 4,4′-dihydroxyl-β-carotene, followed by an oxidation afforded the target product canthaxanthin. The overall yield of this route is 37% from α-ionone. The synthetic steps are easily operated and are practical for the large-scale production.
- Pi, Shiqing,Xi, Meiyang,Deng, Liping,Xu, Huiting,Feng, Chengjie,Shen, Runpu,Wu, Chunlei
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p. 493 - 497
(2019/11/03)
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- Selective oxygenation of ionones and damascones by fungal peroxygenases
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Apocarotenoids are among the most highly valued fragrance constituents, being also appreciated as synthetic building blocks. This work shows the ability of unspecific peroxygenases (UPOs, EC1.11.2.1) from several fungi, some of them being described recently, to catalyze the oxyfunctionalization of α- and β-ionones and α- and β-damascones. Enzymatic reactions yielded oxygenated products such as hydroxy, oxo, carboxy, and epoxy derivatives that are interesting compounds for the flavor and fragrance and pharmaceutical industries. Although variable regioselectivity was observed depending on the substrate and enzyme, oxygenation was preferentially produced at the allylic position in the ring, being especially evident in the reaction with α-ionone, forming 3-hydroxy-α-ionone and/or 3-oxo-α-ionone. Noteworthy were the reactions with damascones, in the course of which some UPOs oxygenated the terminal position of the side chain, forming oxygenated derivatives (i.e., the corresponding alcohol, aldehyde, and carboxylic acid) at C-10, which were predominant in the Agrocybe aegerita UPO reactions, and first reported here.
- Aranda, Carmen,Babot, Esteban D.,Del R?o, José C.,Gutiérrez, Ana,Hofrichter, Martin,Kiebist, Jan,Mart?nez, Angel T.,Scheibner, Katrin,Ullrich, René
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p. 5375 - 5383
(2020/06/08)
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- Fungi-mediated biotransformation of the isomeric forms of the apocarotenoids ionone, damascone and theaspirane
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In this work, we describe a study on the biotransformation of seven natural occurring apocarotenoids by means of eleven selected fungal species. The substrates, namely ionone (α-, β- and γ-isomers), 3,4-dehydroionone, damascone (α- and β-isomers) and theaspirane are relevant flavour and fragrances components. We found that most of the investigated biotransformation reactions afforded oxidized products such as hydroxy- keto- or epoxy-derivatives. On the contrary, the reduction of the keto groups or the reduction of the double bond functional groups were observed only for few substrates, where the reduced products are however formed in minor amount. When starting apocarotenoids are isomers of the same chemical compound (e.g., ionone isomers) their biotransformation can give products very different from each other, depending both on the starting substrate and on the fungal species used. Since the majority of the starting apocarotenoids are often available in natural form and the described products are natural compounds, identified in flavours or fragrances, our biotransformation procedures can be regarded as prospective processes for the preparation of high value olfactory active compounds.
- Serra, Stefano,De Simeis, Davide
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- Total Synthesis of (+)-Granatumine A and Related Bislactone Limonoid Alkaloids via a Pyran to Pyridine Interconversion
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We report the first total synthesis of (+)-granatumine A, a limonoid alkaloid with PTP1B inhibitory activity, in ten steps. Over the course of this study, two key methodological advances were made: a cost-effective procedure for ketone α,β-dehydrogenation using allyl-Pd catalysis, and a Pd-catalyzed protocol to convert epoxyketones to 1,3-diketones. The central tetrasubstituted pyridine is formed by a convergent Knoevenagel condensation and carbonyl-selective electrocyclization cascade, which was followed by a direct transformation of a 2H-pyran to a pyridine. These studies have led to the structural revision of two members of this family.
- Schuppe, Alexander W.,Zhao, Yizhou,Liu, Yannan,Newhouse, Timothy R.
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supporting information
p. 9191 - 9196
(2019/06/17)
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- In Vitro Regio- and Stereoselective Oxidation of β-Ionone by Human Liver Microsomes
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The metabolism of the norisoprenoid β-ionone was investigated in vitro using human liver microsomes and 11 different recombinant cytochrome P450 enzymes expressed in Trichoplusia ni cells. β-Ionone was found to be oxidized via 4S-hydroxylation by CYP2B6 i
- Marumoto, Shinsuke,Shimizu, Ryoyu,Tanabe, Genzoh,Okuno, Yoshiharu,Miyazawa, Mitsuo
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p. 292 - 299
(2017/02/26)
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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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- Expansion of first-in-class drug candidates that sequester toxic all-trans-retinal and prevent light-induced retinal degeneration
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All-trans-retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all-trans-retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11-cis-retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all-trans-retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all-trans-retinyl ester into 11-cis-retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation.
- Zhang, Jianye,Dong, Zhiqian,Mundla, Sreenivasa Reddy,Hu, X. Eric,Seibel, William,Papoian, Ruben,Palczewski, Krzysztof,Golczak, Marcin
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supporting information
p. 477 - 491
(2015/01/30)
-
- First enantioselective synthesis of marine diterpene ambliol-A
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The first enantioselective synthesis of furanditerpene ambliol-A, which is a major metabolite of marine sponge Dysidea amblia, has been accomplished by starting from racemic α-ionone. The key steps of the synthesis include lipase-mediated resolution of 4-hydroxy-γ-ionone, its stereoselective transformation into trans-α-epoxy-dihydroionone, C2 homologation to trans-α-epoxy-monocyclofarnesyl acetate and Li2CuCl4-catalysed sp3-sp3 cross-coupling reaction of the latter ester with (furan-3-ylmethyl)magnesium chloride. This work confirms the chemical structure previously assigned to ambliol-A and proves that the natural levorotatory isomer does not possess (1S,2S) absolute configuration, as previously indicated, but is the opposite enantiomer, (1R,2R)-2-[(E)-6-(furan-3-yl)-3-methylhex-3-enyl]-1,3,3-trimethylcyclohexanol.
- Serra, Stefano,Lissoni, Veronica
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p. 2226 - 2234
(2015/04/14)
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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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- 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 and in vitro characterization of ionone-based compounds as dual inhibitors of the androgen receptor and NF-κB
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Current therapeutic strategy for advanced prostate cancer is to suppress the androgen receptor (AR) signaling. However, lethal castration-resistant prostate cancer (CRPC) arises due to AR reactivation via multiple mechanisms, including mutations in the AR and cross-talk with other pathways such as NF-κB. We have previously identified two ionone-based antiandrogens (SC97 and SC245), which are full antagonists of the wild type and the clinically-relevant T877A, W741C and H874Y mutated ARs. Here, we discovered SC97 and SC245 also inhibit NF-κB. By synthesizing a series of derivatives of these two compounds, we have discovered a novel compound 3b that potently inhibits both AR and NF-κB signalling, including the AR F876L mutant. Compound 3b showed low micromolar antiproliferative activites in C4-2B and 22Rv1 cells, which express mutated ARs and are androgen-independent, as well as DU-145 and PC-3 cells, which exhibit constitutively activated NF-κB signalling. Our studies indicate 3b is effective against the CRPC cells.
- Liu, Weiguo,Zhou, Jinming,Geng, Guoyan,Lin, Rongtuan,Wu, Jian Hui
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p. 227 - 234
(2014/04/03)
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- Oxidation of alkenes with non-heme iron complexes: Suitability as an organic synthetic method
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In the course of a preliminary study to determine the preparative value and the synthetic applications of the non-heme iron(II) complexes Fe(bpmen)(OTf)2 and Fe(tpa)(OTf)2, in particular the oxidation of alkenes by using hydrogen peroxide as the terminal oxidant, we have found significant differences in catalyst behavior. After several attempts it was clear that the preparative relevance of the oxidation processes was linked to the concentration of the catalyst and optimal results were obtained when the concentration value was 5 mol %. At that concentration, the Fe(bpmen)(OTf)2 catalyst mostly gave rise to mixtures of the epoxide and the trans-dihydroxylation products formed by water-assisted hydrolytic cleavage of the epoxides. Furthermore, the use of the tripodal ligand tpa led to cis dihydroxylation products. When deactivated olefins were used as substrates for the oxidation reaction, the cis-diols were obtained exclusively, although with modest conversions, regardless of the catalyst used.
- Clemente-Tejeda, David,Bermejo, Francisco A.
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p. 9381 - 9386
(2015/03/05)
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- Non-heme iron catalysis in CC, C-H, and CH2 oxidation reactions. Oxidative transformations on terpenoids catalyzed by Fe(bpmen)(OTf)2
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The oxidation of terpene olefins with hydrogen peroxide in the presence of the non-hemo catalyst 5a afforded mixtures of epoxides whose composition was dependent upon the oxidation protocol used in each case. With terpenoid enones, the mixtures obtained evolved from clean epoxidation of α-ionone 23 to the clean allylic oxidation of damascone 28 due to the progressive deactivation of the electron density on the double bonds present in this series. The oxidation of bicyclic and tricyclic terpenoids afforded oxidation products coming from epoxidation, to olefin degradation, methyne and methylene activation products. Probably, the most attractive result was the synthesis of the Magnus lactone 46, from the tricyclic ether 45, with 88% yield and 100% conversion.
- Clemente-Tejeda, David,López-Moreno, Alejandro,Bermejo, Francisco A.
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supporting information
p. 2977 - 2986
(2013/03/29)
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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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- Facile lipase catalysed syntheses of (S)-(+)-4-hydroxy-β-ionone and (S)-(+)-4-hydroxy-β-damascone: Chiral flavorants and synthons
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Enantioselective syntheses of (S)-(+)-4-hydroxy-β-ionone and (S)-(+)-4-hydroxy-β-damascone have been achieved through pig pancreatic lipase catalysed trans-esterification. These molecules find utility as constituent in fruit-type fragrance and flavor form
- More, Gauri P.,Bhat, Sujata V.
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p. 4148 - 4149
(2013/07/26)
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- Synthetic analogues of abscisic acid with anti-inflammatory and insulin release stimulation effects on human cells
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Compound of formula (I) as drug, having abscisic acid antagonist activity and insulin release stimulating activity, in particular for treatment of inflammatory pathologies of type 2 diabetes. Compound of formula (I) wherein R is selected from hydrogen e =O groups, R1 is selected from -H e -OH, R2 is selected from groups having one of following structural formulae (II), (III): wherein X is selected from -OH, optionally substituted alkylamino-, arylamino-, alkylarylamino- or arylalkylamino-, alkoxy-, aryloxy-, alkylaryloxy- or arylalkoxy- groups, with said groups having from one to eight carbon atoms, with the alkyl chains of such groups being optionally branched, containing unsaturations or forming rings, said groups optionally containing atoms or functionalities different from C, salts of said compound or pharmaceutically acceptable precursors thereof, metabolites, hydrates or solvates thereof, for use as a drug.
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Page/Page column 5
(2012/11/06)
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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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- Expedient construction of the ziegler intermediate useful for the synthesis of forskolin via consecutive rearrangements
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"Chemical Equation Presented" The Ziegler Intermediate, useful for the total synthesis of forskolin, was synthesized in 10 reaction steps starting from commercially available a-lonone. This highly efficient synthesis relies on the success of two consecuti
- Ye, Heping,Deng, Gang,Liu, Jun,Qiu, Fayang G.
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supporting information; experimental part
p. 5442 - 5444
(2010/02/28)
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- A convenient cross-metathesis approach to trisporins
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Three series of trisporins have been prepared using a strategy in which a cross-metathesis is the key step. This reaction has proved to be highly regioselective, allowing the combination of α- or β-ionone derivatives having a 1,1-disustituted olefin with
- López-Sánchez, Cristóbal,Hernández-Cervantes, Carmen,Rosales, Antonio,álvarez-Corral, Míriam,Mu?oz-Dorado, Manuel,Rodríguez-García, Ignacio
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scheme or table
p. 9542 - 9549
(2010/02/27)
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- Synthesis, olfactory evaluation, and determination of the absolute configuration of the 3,4-didehydroionone stereoisomers
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The synthesis of 3,4-didehydroionone isomers 4, (+)-6, and (-)-6 and of 3,4-didehydro-7,8-dihydroionone isomers 5, (+)-7, and (-)-7 was accomplished starting from commercially available racemic α-ionone (1). Their preparation of the racemic forms 4-7 was first achieved by mean of a number of chemo- and regioselective reactions (Schemes 1 and 2). The enantio- and diastereoselective lipase-mediated kinetic acetylation of 4-hydroxy-γ- ionone (10a/10b) provided 4-hydroxy-γ-ionone (+)-10a/(±)-10b and (+)-4-(acetyloxy)-γ-ionone ((+)12b) (Scheme 3). The latter compounds were used as starting materials to prepare the 3,4-didehydro-γ-ionones (+)- and (-)-6 and the 3,4-didehydro-7,8-dihydro-γ-ionones (+)- and (-)-7 in enantiomer-enriched form. The absolute configuration of (+)-12b was determine by chemical correlation with (+)-(6S)-γ-ionone ((+)-3) and with (-)-(6S)-α-ionone ((-)-1) therefore allowing to assign the (S)-configuration to (+)-6 and (+)-7. Olfactory evaluation of the above described 3,4-didehydroionone isomers shows a significant difference between the enantiomers and regioisomers both in fragrance feature and in detection threshold (Table).
- Serra, Stefano,Fuganti, Claudio,Brenna, Elisabetta
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p. 1110 - 1122
(2007/10/03)
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- Enantioselective synthesis of 1(R)-hydroxypolygodial
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Enantioselective preparation of 1(R)-hydroxypolygodial (5) has been achieved starting from α-ionone through a synthetic strategy involving a Corey-Bakshi-Shibata oxazaborolidine-mediated reduction and a stereoselective Diels-Alder reaction as key steps.
- Della Monica, Carmela,Della Sala, Giorgio,D'Urso, Deborah,Izzo, Irene,Spinella, Aldo
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p. 4061 - 4063
(2007/10/03)
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- Efficient electrophilic and nucleophilic epoxidations utilizing a sulfonylperoxy radical and peroxysulfate species
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Reaction of superoxide anion radical (O2-. with o-nitrobenzenesulfonyl chloride yields a o-nitrobenzenesulfonyl peroxy radical with strong oxidizing ability, which is capable of oxidizing aryl methylene moieties to aryl ketones and relatively electron-rich alkenes regioselectively to epoxides. The oxidizing species is tentatively attributed to the o-nitrobenzenesulfonyl peroxy radical of structure 1. Tetrabutylammonium peroxydisulfate (TBA)2S2O8, 2) was prepared by the reaction of tetrabutylammonium hydrogen sulfate with potassium peroxydisulfate. The epoxidation of enals and enones, such as α,β-unsaturated aldehydes or ketones, was efficiently achieved with 2 in the presence of hydrogen peroxide and base in acetonitrile or in methanol at 25°C. A base-sensitive substrate, such as cinnamaldehyde, could be successfully epoxidized under mild reaction conditions and in short reaction time.
- Park, Min Young,Yang, Seung Gak,Kim, Yong Hae
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p. 431 - 436
(2007/10/03)
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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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- C-15 phosphonate reagent compositions for the manufacture of compounds such as canthaxanthin and methods of synthesizing the same
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The present invention describes novel C-15 allenic phosphonate reagent compositions of the formula: STR1 The invention also describes novel C-15 allylic phosphonate reagent compositions of the formula: STR2 The invention also describes methods of preparing canthaxanthin, the phosphonate reagent compositions, and a tertiary propargylic alcohol of the formula: STR3
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- Diastereoface-selective epoxidations: Dependency on the reagent electrophilicity
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Substrate-imposed steric constraints can be overriden by the pronounced preference of strong peracids for epoxidation on the π face, which has the highest electron density. For example, the sy:anti ratio for reaction (1) with CF3CO3H in CH2Cl2 is 82:18, that with CH3CO3H in toluene is 3:97.
- Fehr, Charles
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p. 2407 - 2409
(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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- A versatile cobalt(II)-Schiff base catalyzed oxidation of organic substrates with dioxygen: Scope and mechanism
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Cobalt(II) complex 1a-f derived from Schiff bases act as efficient catalysts during the oxidation of wide range of organic substrates(e.g. alkenes, alcohols, benzylic compounds and aliphatic hydrocarbons) with dioxygen in the presence of aliphatic aldehydes or ketones or ketoesters. EPR studies on 1a-f complexes suggest that the aliphatic carbonyl compounds promote the formation of a cobalt(II)-superoxo species responsible for the oxidation of organic compounds. These studies also demonstrate the role of ligands on cobalt in controlling the chemoselectivity of these oxidations. A plausible mechanistic rational is also provided for these oxidations.
- Punniyamurthy,Bhatia, Beena,Reddy, M. Madhava,Maikap, Golak C.,Iqbal, Javed
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p. 7649 - 7670
(2007/10/03)
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- A Halide-Free Method for Olefin Epoxidation with 30% Hydrogen Peroxide
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A catalytic system consisting of sodium tungstate dihydrate, (aminomethyl) phosphonic acid, and methyltrioctylammonium Hydrogensulfate, effects the epoxidation of olefins using 30% hydrogen peroxide with a substrate-to-catalyst molar ratio of 50 - 500. The reaction proceeds in high yield without solvents, or, alternatively, with added toluene under entirely halide-free conditions. Lipophilic ammonium hydrogensulfate, which replaces the conventional chloride, and an (α-aminoalkyl)phosphonic acid are crucial for the high reactivity. This method is operationally simple, environmentally benign, and much more economical than the oxidation with m-chloroperbenzoic acid, allowing for a large-scale preparation of epoxides. Various substrates including terminal olefins, 1,1- and 1,2-disubstituted olefins, cyclic olefins, and tri- and tetrasubstituted olefins as well as allylic alcohols, esters, α,β-unsaturated ketones, and ethers can be epoxidized in high yield. The scope and limitations of this new reaction system are discussed.
- Sato, Kazuhiko,Aoki, Masao,Ogawa, Masami,Hashimoto, Tadashi,Panyella, David,Noyori, Ryoji
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p. 905 - 915
(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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The electrocyclisation of allenyldiene easily obtained from hydroxy-β-ionone has been studied with the aim to set up an efficient access to polyhydroxylated decalinic systems. Some aspects of the stereoselectivity of this reaction are discussed and the tr
- Leclaire,Jean,Lopez,Ricard,Plessix,Lallemand
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p. 6983 - 6998
(2007/10/02)
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- Microbial synthesis of optically pure (R)-2,4,4-trimethyl-3-(2'-hydroxyethyl)-cyclohex-2-en-1-ol, a new and versatile chiral building block for terpene synthesis
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The hydroxylation of 2,4,4-trimethyl-3-(2'-hydroxyethyl)-2-cyclohexene by Mucor plumbeus, after usual work up and a subsequent single crystallization, gave the corresponding optically pure (1R)-hydroxy synthon.
- Aranda,Bertranne,Azerad,Maurs
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p. 675 - 678
(2007/10/02)
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- A Novel Method for the Preparation of Acid-Sensitive Epoxides from Olefins with the Combined Use of Molecular Oxygen and Aldoacetal Catalyzed by a Cobalt(II) Complex
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An efficient synthesis of acid-sensitive epoxides, such as chromene oxide or epoxide of γ,δ-unsaturated alcohol, was successfully achieved by the oxygenation of corresponding olefins with the combined use of an atmospheric pressure of molecular oxygen and aldoacetal catalyzed by a cobalt(II) complex coordinated with the 1,3-diketone ligand.The reactions proceeded under mild and neutral conditions, and the desired epoxides were obtained in good yields.Neither overoxidation nor decomposition of the formed epoxide was observed under the present reaction conditions.Furthermore, various silyl enol ethers and silyl ketene acetals, acid-sensitive compounds, were also smoothly monooxygenated into the corresponding α-hydroxy ketones and α-hydroxy carboxylic acid esters, respectively.
- Yorozu, Kiyotaka,Takai, Toshihiro,Yamada, Tohru,Mukaiyama, Teruaki
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p. 2195 - 2202
(2007/10/02)
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- Aerobic Epoxidation of Olefins Catalyzed by Cobalt(II) Complex Using Propionaldehyde Diethyl Acetal as a Reductant
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In the presence of bis(3-methyl-2,4-pentanedionato)cobalt(II) complex catalyst, various trisubstituted olefins are smoothly monooxygenated into the corresponding epoxides in high yields under neutral conditions by the combined use of molecular oxygen and propionaldehyde diethyl acetal.
- Mukaiyama, Teruaki,Yorozu, Kiyotaka,Takai, Toshihiro,Yamada, Tohru
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p. 439 - 442
(2007/10/02)
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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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- Practical Total Synthesis of (+/-)-Strigol
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An improved total synthesis of racemic strigol (1) and 4'-epistrigol (21) from α-ionone in 10 (4.4percent overall yield) or 12 steps (6.8percent overall yield) by recycling isomer 16 is described which is applicable on a multigram scale with a minimum of
- Brooks, Dee W.,Bevinakatti, H. S.,Kennedy, Eileen,Hathaway, Jim
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p. 628 - 632
(2007/10/02)
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- Photochemical Reactions. Photochemistry of α,β-Unsaturated δ,ε-Epoxyketones of the Ionone Series
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On n,?*- as well as on ?,?*-excitation, the 4,5-epoxy-α-ionones (E)-1, (E)-2, and (E)-3 undergo (E)/(Z)-isomerization and subsequent γ-H-abstraction leading to the corresponding 4-hydroxy-β-ionones (E/Z)-9, E/Z)-13, and (E/Z)-17 as primary photoproducts.On photolysis of (E)-3, as an additional primary photoproduct, the β,γ-unsaturated δ,ε-epoxy ketone 18 was obtained.The other isolated compounds, namely the 2H-pyrans 10A+B and 14A+B as well as the retro-γ-ionones 11 and 15A+B, represent known types of products which are derived from the 4-hydroxy-β-ionones (E/Z)-9 and (E/Z)-13, respectively.
- Mathies, Peter,Frei, Bruno,Jeger, Oskar
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p. 192 - 206
(2007/10/02)
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- Facile and Regioselective Epoxidations of Olefins with a Peroxysulfur Intermediate Generated from Superoxide Anion (O2-.) and Nitrobenzenesulfonyl Chlorides
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A peroxysulfur intermediate generated from the reaction of o- or p-nitrobenzenesulfonyl chloride with superoxide anion (O2-.) is found to be an excellent oxidizing reagent for the facile and regioselective epoxidation of olefins at -35 deg C.
- Kim, Yong Hae,Chung, Bong Chul
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p. 1562 - 1564
(2007/10/02)
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- 2. Synthese von (-)-(R)-4-Hydroxy-β-ionon und (-)-(5R,6S)-5-Hydroxy-4,5-dihydro-α-ionon aus (-)-(S)-α-Ionon
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The absolute configuration of the chiral 4-hydroxy-β-ionones and 5-hydroxy-4,5-dihydro-α-ionones has been determined by chemical connection with (-)-(S)-α-ionone i.e. by stereoselective epoxidation of the latter, followed by base catalyzed opening of the epoxide as well as by its hydride reduction.
- Haag, von Andreas,Eschenmoser, Walter,Eugster, Conrad Hans
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- 1-(2,6,6-Trimethyl-3-hydroxy-1-cyclohexen-1-yl)-3-methyl-penta-1,4-diene[or 1-yn-4-EN]-3-ols
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A total synthesis of canthaxanthin, a known food coloring agent from alpha or retro ionone.
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