- PQQ-dependent Dehydrogenase Enables One-pot Bi-enzymatic Enantio-convergent Biocatalytic Amination of Racemic sec-Allylic Alcohols
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The asymmetric amination of secondary racemic allylic alcohols bears several challenges like the reactivity of the bi-functional substrate/product as well as of the α,β-unsaturated ketone intermediate in an oxidation-reductive amination sequence. Heading for a biocatalytic amination cascade with a minimal number of enzymes, an oxidation step was implemented relying on a single PQQ-dependent dehydrogenase with low enantioselectivity. This enzyme allowed the oxidation of both enantiomers at the expense of iron(III) as oxidant. The stereoselective amination of the α,β-unsaturated ketone intermediate was achieved with transaminases using 1-phenylethylamine as formal reducing agent as well as nitrogen source. Choosing an appropriate transaminase, either the (R)- or (S)-enantiomer was obtained in optically pure form (>98 % ee). The enantio-convergent amination of the racemic allylic alcohols to one single allylic amine enantiomer was achieved in one pot in a sequential cascade.
- Gandomkar, Somayyeh,Rocha, Raquel,Sorgenfrei, Frieda A.,Montero, Lía Martínez,Fuchs, Michael,Kroutil, Wolfgang
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p. 1290 - 1293
(2020/12/23)
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- Method for preparing beta-ionone through cyclization
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The invention discloses a method for preparing beta-ionone through cyclization. The method comprises the following steps: with pseudoionone as a raw material, performing cyclization on the pseudoionone through a catalyst, namely concentrated sulfuric acid
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Paragraph 0024-0080
(2020/06/02)
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- An unexpected generation of magnetically separable Se/Fe3O4 for catalytic degradation of polyene contaminants with molecular oxygen
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Selenization of Fe2O3 with NaHSe led to Se/Fe3O4. The unexpected generation of Fe3O4 attributed to the reduction conditions of the reaction, and the resulted magnetic features of the materi
- Chen, Xingyu,Mao, Jingfei,Liu, Chuang,Chen, Chao,Cao, Hongen,Yu, Lei
-
supporting information
p. 3205 - 3208
(2020/08/12)
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- Iodine/water-mediated deprotective oxidation of allylic ethers to access α,β-unsaturated ketones and aldehydes
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The first iodine/water-mediated deprotective oxidation of allylic ethers to access α,β-unsaturated ketones and aldehydes was achieved. The reaction tolerates a wide range of functionalities. Furthermore, this protocol was found to be applicable to the oxidative transformation of allylic acetates. The proposed mechanism involves an oxygen transfer from solvent water to the carbonyl products.
- Chen, Weifeng,Jiang, Kezhi,Xue, Yuntian,Yan, Yaolong,Yang, Lei
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p. 14720 - 14724
(2020/04/27)
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- Scalable synthesis of the aroma compounds d6-β-ionone and d6-β-cyclocitral for use as internal standards in stable isotope dilution assays
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C13 Norisoprenoids are important aroma compounds in wine, giving positive attributes to the overall wine aroma even when found at very low levels. β-Ionone is considered one of the most important aroma compounds giving violet, woody and raspberry aromas to wine, fruits and vegetables in which it is found. Due to its potent aroma at low levels, precise analytical methods are desired for its quantification. Stable isotope dilution assay (SIDA) is one of the most important of these methods but requires the use of isotopically labelled standards. Herein, we describe the scalable synthesis of d6-β-ionone and d6-β-cyclocitral, another aroma compound with smokey and fruity notes, starting from the relatively inexpensive deuterated starting material d6-acetone.
- Mosaferi, Shabnam,Jelley, Rebecca E.,Fedrizzi, Bruno,Barker, David
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-
- Transfer-dehydrogenation of secondary alcohols catalyzed by manganese NNN-pincer complexes
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Novel catalytic systems based on pentacarbonylmanganese bromide and stable NNN-pincer ligands are presented for the transfer-dehydrogenation of secondary alcohols to give the corresponding ketones in good to excellent isolated yields. Best results are obtained using di-picolylamine derivatives as ligands and acetone as an inexpensive hydrogen acceptor. Besides high activity for benzylic substrates, aliphatic alcohols, as well as steroid derivatives, are readily oxidized in the presence of the optimal phosphorus-free catalyst.
- Budweg, Svenja,Junge, Kathrin,Beller, Matthias
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supporting information
p. 14143 - 14146
(2019/12/02)
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- Photocatalytic e → Z Isomerization of β-Ionyl Derivatives
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An operationally simple E → Z isomerization of activated dienes, based on the β-ionyl motif intrinsic to retinal, is reported using inexpensive (-)-riboflavin (vitamin B2) under irradiation at 402 nm. Selective energy transfer from photoexcited (-)-riboflavin to the starting E-isomer enables geometrical isomerization. Since the analogous process with the Z-isomer is inefficient, microscopic reversibility is circumvented, thereby enabling a directional isomerization to generate the contra-thermodynamic product (up to 99% yield, up to 99:1 Z/E). Prudent choice of photocatalyst enables chemoselective isomerization to be achieved in both inter- and intramolecular systems. The principles established from this study, together with a molecular editing approach, have facilitated the development of a regioselective isomerization of a truncated triene based on the retinal scaffold.
- Livingstone, Keith,Tenberge, Marius,Pape, Felix,Daniliuc, Constantin G.,Jamieson, Craig,Gilmour, Ryan
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supporting information
p. 9677 - 9680
(2019/11/29)
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- Biocatalytic Enantioselective Oxidation of Sec-Allylic Alcohols with Flavin-Dependent Oxidases
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The oxidation of allylic alcohols is challenging to perform in a chemo- as well as stereo-selective fashion at the expense of molecular oxygen using conventional chemical protocols. Here, we report the identification of a library of flavin-dependent oxidases including variants of the berberine bridge enzyme (BBE) analogue from Arabidopsis thaliana (AtBBE15) and the 5-(hydroxymethyl)furfural oxidase (HMFO) and its variants (V465T, V465S, V465T/W466H and V367R/W466F) for the enantioselective oxidation of sec-allylic alcohols. While primary and benzylic alcohols as well as certain sugars are well known to be transformed by flavin-dependent oxidases, sec-allylic alcohols have not been studied yet except in a single report. The model substrates investigated were oxidized enantioselectively in a kinetic resolution with an E-value of up to >200. For instance HMFO V465S/T oxidized the (S)-enantiomer of (E)-oct-3-en-2-ol (1 a) and (E)-4-phenylbut-3-en-2-ol with E>200 giving the remaining (R)-alcohol with ee>99% at 50% conversion. The enantioselectivity could be decreased if required by medium engineering by the addition of cosolvents (e. g. dimethyl sulfoxide).
- Gandomkar, Somayyeh,Jost, Etta,Loidolt, Doris,Swoboda, Alexander,Pickl, Mathias,Elaily, Wael,Daniel, Bastian,Fraaije, Marco W.,Macheroux, Peter,Kroutil, Wolfgang
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p. 5264 - 5271
(2019/11/13)
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- Kinetics of β-Carotene Oxidation in the Presence of Highly Active Forms of μ-Carbido Diiron(IV) Tetraphenylporphyrinate
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Abstract: The oxidative destruction of β-carotene in the presence of highly oxidized forms of μ-carbido-bis[(5,10,15,20-tetraphenyl-21H,23H-porphyrinato)iron(IV)] (1 → 3) or its analog with axially coordinated imidazole (2 → 4) obtained under the action of tert-butyl hydroperoxide tBuOOH was studied by spectrophotometry. It was found that compound 3 is the oxo form of compound 1 singly oxidized at the macrocyclic ligand (π radical cation) under the action of which β-carotene is oxidized with a rate constant k = 3.3 L2 mol–2 s–1. A?conclusion is drawn that short-lived compound 4 has unique EAS and is capable of oxidizing tBuOOH to form O2, which makes it possible to consider it the model of peroxidase. The value of k for the reaction with the participation of β-carotene and compound 4 (k = 10.3 L2 mol–2 s–1) is three times higher than that with the participation of compound 3. If a new portion of β-carotene is added, the process of its oxidative destruction in the presence of compounds 3 or 4 occurs without additives of the dimeric complex and peroxide. A?possible nature of compound 4 is discussed, as well as the influence of N-base in the coordination sphere of the complex on the nature of active intermediates and the rate of β-carotene decomposition.
- Simonova,Zaitseva,Tyulyaeva, E. Yu.,Zdanovich,Koifman
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p. 2128 - 2134
(2018/10/24)
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- Method for preparing beta-ionone from modified acidic functionalized ionic liquid
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The invention relates to a method for preparing beta-ionone from modified acidic functionalized ionic liquid. The method includes the following steps that the modified acidic functionalized ionic liquid serves as a catalyst, and pseudo ionone is cyclized into beta-ionone. The modified acidic functionalized ionic liquid serves as the catalyst, the high reactive transformation rate and beta-ionone yield are achieved, the reactive transformation rate reaches 99% or above, and the beta-ionone yield reaches 94% or above. The catalyst can still keep the high transformation rate and yield after being separated and applied mechanically multiple times, the reactive transformation rate still reaches 99% or above, and the reaction yield is still kept at 90% or above.
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-
Paragraph 0044; 0045; 0046; 0046; 0047; 0048; 0049
(2017/09/23)
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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.
- -
-
Paragraph 00169
(2016/06/14)
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- Characterization of hamster NAD+-dependent 3(17)β-hydroxysteroid dehydrogenase belonging to the aldo-keto reductase 1C subfamily
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The cDNAs for morphine 6-dehydrogenase (AKR1C34) and its homologous aldo-keto reductase (AKR1C35) were cloned from golden hamster liver, and their enzymatic properties and tissue distribution were compared. AKR1C34 and AKR1C35 similarly oxidized various xenobiotic alicyclic alcohols using NAD+, but differed in their substrate specificity for hydroxysteroids and inhibitor sensitivity. While AKR1C34 showed 3α/17β/20α-hydroxysteroid dehydrogenase activities, AKR1C35 efficiently oxidized various 3β- and 17β-hydroxysteroids, including biologically active 3β-hydroxy-5α/β-dihydro-C19/C21-steroids, dehydroepiandrosterone and 17β-estradiol. AKR1C35 also differed from AKR1C34 in its high sensitivity to flavonoids, which inhibited competitively with respect to 17β-estradiol (Ki 0.11-0.69 μM). The mRNA for AKR1C35 was expressed liver-specific in male hamsters and ubiquitously in female hamsters, whereas the expression of the mRNA for AKR1C34 displayed opposite sexual dimorphism. Because AKR1C35 is the first 3(17)β-hydroxysteroid dehydrogenase in the AKR superfamily, we also investigated the molecular determinants for the 3β-hydroxysteroid dehydrogenase activity by replacement of Val54 and Cys310 in AKR1C35 with the corresponding residues in AKR1C34, Ala and Phe, respectively. The mutation of Val54Ala, but not Cys310Phe, significantly impaired this activity, suggesting that Val54 plays a critical role in recognition of the steroidal substrate.
- Endo, Satoshi,Noda, Misato,Ikari, Akira,Tatematsu, Kenjiro,El-Kabbani, Ossama,Hara, Akira,Kitade, Yukio,Matsunaga, Toshiyuki
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p. 425 - 434
(2015/11/27)
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- Organoselenium-catalyzed baeyer-villiger oxidation of α,β-unsaturated ketones by hydrogen peroxide to access vinyl esters
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By carefully screening the organoselenium pre-catalysts and optimizing the reaction conditions, simple dibenzyl diselenide was found to be the best pre-catalyst for Baeyer-Villiger oxidation of (E)-α,β-unsaturated ketones with the green oxidant hydrogen peroxide at room temperature. The organoselenium catalyst used in this reaction could be recycled and reused several times. This new method was suitable not only for methyl unsaturated ketones, but also for alkyl and aryl unsaturated ketones. Therefore, it provided a direct, mild, practical, highly functional group-tolerant process for the chemoselective preparation of the versatile (E)-vinyl esters from the readily available (E)-α,β-unsaturated ketones. A possible mechanism was also proposed to rationalize the activity of the organoselenium catalyst in the presence of hydrogen peroxide in this Baeyer-Villiger oxidation reaction.
- Zhang, Xu,Ye, Jianqing,Yu, Lei,Shi, Xinkang,Zhang, Ming,Xu, Qing,Lautens, Mark
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supporting information
p. 955 - 960
(2015/03/30)
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- Carotenoid-cleavage activities of crude enzymes from pandanous amryllifolius
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Carotenoid degradation products, known as norisoprenoids, are aroma-impact compounds in several plants. Pandan wangi is a common name of the shrub Pandanus amaryllifolius. The genus name Pandanus is derived from the Indonesian name of the tree, pandan. In Indonesia, the leaves from the plant are used for several purposes, e.g., as natural colorants and flavor, and as traditional treatments. The aim of this study was to determine the cleavage of β-carotene and β-apo-8-carotenal by carotenoidcleavage enzymes isolated from pandan leaves, to investigate dependencies of the enzymatic activities on temperature and pH, to determine the enzymatic reaction products by using Headspace Solid Phase Microextraction Gas Chromatography/Mass Spectrophotometry (HS-SPME GC/MS), and to investigate the influence of heat treatment and addition of crude enzyme on formation of norisoprenoids. Crude enzymes from pandan leaves showed higher activity against β-carotene than β-apo-8-carotenal. The optimum temperature of crude enzymes was 70°, while the optimum pH value was 6.We identified bionone as the major volatile reaction product from the incubations of two different carotenoid substrates, β-carotene and β-apo-8-carotenal. Several treatments, e.g., heat treatment and addition of crude enzymes in pandan leaves contributed to the norisoprenoid content. Our findings revealed that the crude enzymes from pandan leaves with carotenoid-cleavage activity might provide a potential application, especially for biocatalysis, in natural-flavor industry.
- Ningrum, Andriati,Schreiner, Matthias
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p. 1871 - 1881
(2015/02/19)
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- Activation of DMSO for Swern-type oxidation by 1,1-dichlorocycloheptatriene
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A new dimethylsulfoxide activation method employing 1,1-dichlorocycloheptatriene has been developed for a mild Swern-type oxidation of a variety of alcohols. The carbonyl products can be obtained in good to excellent yields from this operationally simple and efficient method. This work is the first report of dimethylsulfoxide activation by a simple chlorinated hydrocarbon reagent, which has the unique ability of equilibrating to its reactive aromatic cationic form.
- Nguyen, Thanh Vinh,Hall, Michael
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supporting information
p. 6895 - 6898
(2015/01/09)
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- Rabbit 3-hydroxyhexobarbital dehydrogenase is a NADPH-preferring reductase with broad substrate specificity for ketosteroids, prostaglandin D2, and other endogenous and xenobiotic carbonyl compounds
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3-Hydroxyhexobarbital dehydrogenase (3HBD) catalyzes NAD(P) +-linked oxidation of 3-hydroxyhexobarbital into 3-oxohexobarbital. The enzyme has been thought to act as a dehydrogenase for xenobiotic alcohols and some hydroxysteroids, but its physiological function remains unknown. We have purified rabbit 3HBD, isolated its cDNA, and examined its specificity for coenzymes and substrates, reaction directionality and tissue distribution. 3HBD is a member (AKR1C29) of the aldo-keto reductase (AKR) superfamily, and exhibited high preference for NADP(H) over NAD(H) at a physiological pH of 7.4. In the NADPH-linked reduction, 3HBD showed broad substrate specificity for a variety of quinones, ketones and aldehydes, including 3-, 17- and 20-ketosteroids and prostaglandin D2, which were converted to 3α-, 17β- and 20α-hydroxysteroids and 9α,11β- prostaglandin F2, respectively. Especially, α-diketones (such as isatin and diacetyl) and lipid peroxidation-derived aldehydes (such as 4-oxo- and 4-hydroxy-2-nonenals) were excellent substrates showing low Km values (0.1-5.9 μM). In 3HBD-overexpressed cells, 3-oxohexobarbital and 5β-androstan-3α-ol-17-one were metabolized into 3-hydroxyhexobarbital and 5β-androstane-3α,17β-diol, respectively, but the reverse reactions did not proceed. The overexpression of the enzyme in the cells decreased the cytotoxicity of 4-oxo-2-nonenal. The mRNA for 3HBD was ubiquitously expressed in rabbit tissues. The results suggest that 3HBD is an NADPH-preferring reductase, and plays roles in the metabolisms of steroids, prostaglandin D2, carbohydrates and xenobiotics, as well as a defense system, protecting against reactive carbonyl compounds.
- Endo, Satoshi,Matsunaga, Toshiyuki,Matsumoto, Atsuko,Arai, Yuki,Ohno, Satoshi,El-Kabbani, Ossama,Tajima, Kazuo,Bunai, Yasuo,Yamano, Shigeru,Hara, Akira,Kitade, Yukio
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p. 1366 - 1375
(2013/11/19)
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- ω-Sulfonic-perfluoroalkylated poly(styrene-maleic anhydride)/silica hybridized nanocomposite as a new kind of solid acid catalyst
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A new kind of ω-sulfonic-perfluoroalkylated poly(styrene-maleic anhydride)/silica hybrid nanocomposite FSMA/SiO2 has been synthesized under mild conditions by perfluoroalkylation of styrene-maleic anhydride copolymer (SMA) with ω-fluorosulfonylperfluorodiacyl peroxides (SFAP), and followed in turn by aminolysis using (3-aminopropyl)triethoxysilane (APTES), alkali hydrolysis, gelation with tetraethoxysilane (TEOS) and finally acidification. The hybrid solid acid FSMA/SiO2 with terminal perfluoroalkylsulfonic and carboxyl groups was characterized by FTIR, SEM, TEM, TGA, XPS, EDX, acidimetry and nitrogen sorption technique. Its pore structure, acid strength and acid amount were easily modulated by controlling the gelation and perfluoroalkylation conditions. The catalytic activity and selectivity, as well as reusability of FSMA/SiO2 were tested in three important reactions, namely, cyclization of pseudoionone, condensation of indole and esterification of benzoic acid. Owing to the higher exchange capacity than that of Nafion/SiO2, and the stronger acidity than that of Amberlyst-15, the nanocomposite FSMA/SiO2 showed higher activity and selectivity than these commercial solid acids in the reactions.
- Lin, Zhenghuan,Huang, Limei,Ling, Qidan,Chen, Hong,Zhao, Chengxue
-
-
- Cyclization of pseudoionone into α-Ionone over heteropolyacid supported on mesoporous silica SBA-15
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Cyclization of pseudoionone into α-ionone was performed over the series heteropolyacid supported on SBA-15 in liquid-phase at 363 and 373 K using a batch reactor. It has been demonstrated that the liquid-phase synthesis of α-ionone by pseudoionone cyclization can be efficiently achieved on heteropolyacid/SBA-15 materials. The high catalytic performance of PW 12/SBA-15 materials is due to their strong Bronsted acidity, high dispersion of active phase and also to absence of steric constraints for pseudoionone cyclization. PW12/SBA-15 catalysts are specially active and selective for this reaction giving predominantly α-ionone, as the main product, with high yield (about 60% at 373 K after 2 h) close to that obtained via the homogeneous synthesis. This catalytic system is more active and efficient in comparison with heteropolyacid supported on commercial silica. In order to achieve comparable amount of α-ionone, as is got for PW 12/SBA-15, belongs to apply five times more of the catalyst based on classical SiO2.
- Rachwalik,Michorczyk,Ogonowski
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experimental part
p. 1384 - 1390
(2012/02/02)
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- One-pot synthesis of optically active allyl esters via lipase-vanadium combo catalysis
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The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution.
- Akai, Shuji,Hanada, Ryosuke,Fujiwara, Noboru,Kita, Yasuyuki,Egi, Masahiro
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supporting information; experimental part
p. 4900 - 4903
(2011/01/12)
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- Synthesis of ionones on solid Br?nsted acid catalysts: Effect of acid site strength on ionone isomer selectivity
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The effect of Br?nsted acid site strength on the liquid-phase conversion of pseudoionone to ionone isomers (α-, β- and γ-ionone) was studied on resin Amberlyst 35W, silica-supported heteropolyacid (HPAS) and silica-supported triflic acid (TFAS). Catalyst acidity was probed by temperature-programmed desorption of NH3 coupled with infrared spectra of adsorbed pyridine. The initial pseudoionone conversion rate followed the order: TFAS > Amberlyst 35W ≈ HPAS. Synthesis of the three ionone isomers occurred via a common cyclic carbocation intermediate formed from the activation of the pseudoionone molecule on Br?nsted acid sites. Initial ionone mixtures containing a α:β:γ isomer distribution of about 40:20:40 were formed, irrespective of the acid site strength. But the ionone mixture composition changed with the progress of the reaction because γ-ionone was consecutively converted to α-ionone on HPAS and Amberlyst 35W, whereas the stronger acid sites of TFAS converted γ-ionone to β-ionone.
- Díez,Apesteguía,Di Cosimo
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experimental part
p. 267 - 274
(2010/11/19)
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- Generation of norisoprenoid flavors from carotenoids by fungal peroxidases
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To biotechnologlcally produce norisoprenoid flavor compounds, two extracellular peroxidases (MsP1 and MsP2) capable of degrading carotenoids were isolated from the culture supematants of the basidiomycete Marasmlus scorodonlus (garlic mushroom). The encod
- Zelena, Kateryna,Hardebusch, Bjoern,Huelsdau, Baerbel,Berger, Ralf G.,Zorn, Holger
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experimental part
p. 9951 - 9955
(2010/07/18)
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- Process for the preparation of ionones and vitamin A, vitamin A derivatives, carotenes and carotenoids
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The present invention relates to a process for the preparation of β-ionones and/or α-ionones of the formulae II and III by acid catalyzed ring-closing of ψ-ionones of the formula I wherein R1 to R7 are independently selected from hydrogen and C1-C4-alkyl, R8 is selected from hydrogen and C1-C4-alkyl and the hydroxyl group, R9 and R10 are independently selected from hydrogen and C1-C4-alkyl or R9 and R10 form together the oxygen of a carbonyl group, whereby if R9 and R10 form together the oxygen of a carbonyl group no α-isomer is formed comprising: a) reacting a ψ-ionone according to formula I in presence of a concentrated Br?nsted-acid having a pKs 3, and an organic solvent that is substantially immiscible with the concentrated acid and with an diluted aqueous solution of said acid; b) hydrolysis of the reaction product obtained in step a) by addition of water; and phase separation into an organic phase comprising the β-ionone and/or the α-ionone of the formulae II and III and into an aqueous diluted acid phase; wherein water is added in the hydrolysis step b) in an amount to achieve an acid concentration in said aqueous diluted acid phase of 45 to 65 wt-%, that also can be easily integrated in a process for the preparation of vitamin A, a vitamin A derivative, a carotene or a carotenoid.
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Page/Page column 7-8
(2008/12/05)
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- Gold-catalyzed cycloisomerization of cyclopropyl alkynyl acetates: A versatile approach to 5-, 6-, and 7-membered carbocycles
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Nonclassical chirality transfer? Depending on the substitution pattern of propargyl acetates, a gold-catalyzed homologous Rautenstrauch reaction generates either 5- or 6-membered ring systems (see scheme). The stabilization of cationic intermediates is crucial for this reaction to succeed. The underlying principle for the good chirality transfer observed could be gold-stabilized nonclassical carbocations having configurational stability.
- Zou, Yue,Garayalde, David,Wang, Quanrui,Nevado, Cristina,Goeke, Andreas,Ito, Yoshihiko
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supporting information; experimental part
p. 10110 - 10113
(2009/05/30)
-
- Evaluation of the formation and stability of hydroxyalkylsulfonic acids in wines
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The presence of carbonyl compounds (CCs) in wines has sparked the interest of researchers in several countries. The quantification of some of these compounds has been used as a parameter of quality for many fermented beverages. Although present in minute quantities (except for acetaldehyde), they have a strong olfactory impact. In addition, the CCs found in wines have a strong affinity for bisulfite and can form stable adducts, which will also interfere in the characteristics of aroma. The greatest challenge, however, is to predict which CCs have the strongest affinity for S(IV) and what conditions favor this interaction. To better understand the reaction of CC-bisulfite adduct formation (HASA), this study has evaluated the profile of 22 CCs in a "synthetic wine" containing bisulfite and in 10 real samples of different wines from the Sao Francisco Valley, northeastern Brazil. On the basis of principal component analysis (PCA) and dissociation constants, the results revealed that aliphatic aldehydes form adducts with S(IV), whereas ketones, cyclic aldehydes, and trans-alkenes interact weakly and are found predominantly in their free form. These results revealed also that pH 10 and 11 were defined as the most appropriate for CC-SO2 adduct dissociation, and the total CCs were quantified reliably.
- De Azevedo, Luciana C.,Reis, Marina M.,Motta, Luiz F.,Da Rocha, Gisele O.,Silva, Luciana A.,De Andrade, Jailson B.
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scheme or table
p. 8670 - 8680
(2009/09/28)
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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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- Accurate measurements of 13C-13C J-couplings in the rhodopsin chromophore by double-quantum solid-state NMR spectroscopy
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A new double-quantum solid-state NMR pulse sequence is presented and used to measure one-bond 13C-13C J-couplings in a set of 13C2-labeled rhodopsin isotopomers. The measured J-couplings reveal a perturbation of the electronic structure at the terminus of the conjugated chain but show no evidence for protein-induced electronic perturbation near the C11-C12 isomerization site. This work establishes NMR methodology for measuring accurate 1JCC values in noncrystalline macromolecules and shows that the measured J-couplings may reveal local electronic perturbations of mechanistic significance. Copyright
- Lai, Wai Cheu,McLean, Neville,Gansmueller, Axel,Verhoeven, Michiel A.,Antonioli, Gian Carlo,Carravetta, Marina,Duma, Luminita,Bovee-Geurts, Petra H. M.,Johannessen, Ole G.,De Groot, Huub J. M.,Lugtenburg, Johan,Emsley, Lyndon,Brown, Steven P.,Brown, Richard C. D.,DeGrip, Willem J.,Levitt, Malcolm H.
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p. 3878 - 3879
(2007/10/03)
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- Macroreticular p-(ω-sulfonic-perfluoroalkylated) polystyrene ion-exchange resins: A new type of selective solid acid catalyst
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Macroreticular p-(ω-sulfonic-perfluoroalkylated) polystyrene (FPS) cation-exchange resins 3 have been synthesized by sequential p-perfluoroalkylation of macroreticular polystyrene (PS) 1 with ω-fluorosulfonylperfluorodiacyl peroxide 2, hydrolysis and acidification; the fluorinated mesoporous resins exhibited higher activity and selectivity than commercial Amberlyst 36 and Nafion NR50 in the cyclization of pseudoionone. The Royal Society of Chemistry 2005.
- Lin, Zhenghuan,Zhao, Chengxue
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p. 3556 - 3558
(2007/10/03)
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- Effect of cis/trans isomerism of β-carotene on the ratios of volatile compounds produced during oxidative degradation
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β-Carotene is, when cleaved, an important source of flavor and aroma compounds in fruits and flowers. Among these aroma compounds, the main degradation products are β-ionone, 5,6-epoxy-β-ionone, and dihydroactinidiolide (DHA), which are associated by flavorists and perfumers with fruity, floral, and woody notes. These three species can be produced by degradation of β-carotene through an attack by enzyme-generated free radicals and a cleavage at the C9-C10 bond. This study investigated the influence of cis/trans isomerism at the C9-C10 bond on the production of β-carotene degradation compounds, first with a predictive approach and then experimentally with different isomer mixtures. β-Carotene solutions containing high ratios of 9-cis-isomers produced more DHA, suggesting a different pathway than for the transformation of all-trans-β-carotene to ionone and DHA. These results are important in the search for financially viable processes to produce natural carotene-derived aroma compounds.
- Wache, Yves,Bosser-DeRatuld, Aurelie,Lhuguenot, Jean-Claude,Belin, Jean-Marc
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p. 1984 - 1987
(2007/10/03)
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- Enzymatic carotenoid cleavage in star fruit (Averrhoa carambola)
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This paper presents the first description of an enzyme fraction exhibiting carotenoid cleavage activity isolated from fruit skin of Averrhoa carambola. Partial purification of the enzyme could be achieved by acetone precipitation, ultrafiltration (300 kDa
- Fleischmann, Peter,Watanabe, Naoharu,Winterhalter, Peter
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p. 131 - 137
(2007/10/03)
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- Synthesis of β-ionone
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Preparation of β-ionone by a reaction sequence starting from acetone is described.
- Vani,Chida,Srinivasan,Chandrasekharam,Singh
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p. 219 - 224
(2007/10/03)
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- A mild and efficient method for selective cleavage of ketals and acetals using lithium chloride in water - Dimethyl sulfoxide
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A mild anil efficient neutral aqueous method for selective cleavage of acetals and ketals to the corresponding carbonyl compounds has been established by using LiCI in H2O-DMSO at elevated temperature. While aryl and α,β-unsaturated ketals and acetals underwent smooth cleavage, diaryl, non-aryl and isolated ketals and acetals remained unaffected under the reaction conditions.
- Mandal, Pijus Kumar,Dutta, Pinak,Roy, Subhas Chandra
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p. 7271 - 7274
(2007/10/03)
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- Facile regeneration of carbonyl compounds from oximes and tosylhydrazones with TBHP
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70% tert-Butyl hydroperoxide (TBHP) has been found to be an efficient and selective reagent for the mild oxidative cleavage of the C=N of oximes and tosylhydrazones to yield their corresponding carbonyl compounds.
- Barhate,Gajare,Wakharkar,Sudalai
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p. 653 - 656
(2007/10/03)
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- Deblocking of dithioacetals and oxathioacetals using periodic acid under mild nonaqueous conditions
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A novel method for the deblocking of the dithioacetals and oxathioacetals is described. Periodic acid under nonaqueous conditions has been used for the deprotection of the dithio- and oxathio-derivatives to the corresponding carbonyl compounds. This simple high-yield transformation is conveniently carried out in nonaqueous medium and works well with complex sensitive aldehydes and in the presence of other protective groups.
- Shi, Xiao-Xin,Khanapure, Subhash P.,Rokach, Joshua
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p. 4331 - 4334
(2007/10/03)
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- Epoxy-pyronene: Obtention of cyclocitrals from ionones and precursor of new terpenic compounds
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The selective obtention of epoxy-pyronene from δ-pyronene has been realized using metachloroperbenzoic acid. The isomerization of this epoxidic compound with Lewis and protonic acids and on active alumina has been studied leading to cyclocitrals. Ionones are obtained from epoxy-pyronene by homologation with various C3 units, in the presence of paratoluenesulfonic acid in order to obtain β-cyclocitral in situ. New terpenic compounds with the cyclogeranyl skeleton were obtained from epoxy-pyronene by reduction followed by homologation.
- Marc,Soulet,Serramedan,Delmond
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p. 3381 - 3388
(2007/10/02)
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- DIOXIRANES IN ORGANOMETALLIC CHEMISTRY. III. DECOMPLEXATION OF TRICARBONYL(η4-DIENE)IRON AND μ-(η2-ALKYNE)HEXACARBONYLDICOBALT COMPLEXES
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The applicability of dimethyldioxirane to the release of organic ligands present in models of the title metal complexes has been studied.In both cases, the decomplexation process takes place at slow rates, with good conversion yields.However, the release of the organic ligand competes with the oxidation of unsaturated moities present in the released compound.This fact should be considered in assessing the advantages of dimethyldioxirane in front of the conventional reagents used for the release of organic ligands from these metal complexes.
- Lluch, Anna-Maria,Jordi, Lurdes,Sanchez-Baeza, Francisco,Ricart, Susagna,Camps, Francisco,et al.
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p. 407 - 411
(2007/10/02)
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- Oxidative degradation of β-carotene and β-apo-8′-carotenal
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In the self-initiated oxidation of β-carotene with molecular oxygen the rate of oxygen uptake was shown to depend on the oxygen partial pressure. Epoxides, dihydrofurans, carbonyl compounds, carbon dioxide, oligomeric material, traces of alcohols, and probably carboxylic acids were formed. The main products in the early stage of the oxidation were shown to be 5,6-epoxy-β-carotene. 15,15′-epoxy-′-carotene, diepoxides, and a series of β-apo-carotenals and -carotenones. As the oxidation proceeded uncharacterised oligomeric material and the carbonyl compounds became more important and the epoxides degraded. In the final phase of the oxidation the longer chain β-apo-carotenals were themselves oxidized to shorter chain carbonyl compounds, particularly β-apo-13-carotenone, β-ionone, 5,6-epoxy-gb-ionone, dihydroactinidiolide and probably carboxylic acids. The effect of iron, copper and zinc stearates on the product composition and proportions was studied, as was the effect of light. The oxidation was inhibited by 2,6-di-t-butyl-4-methyphenol and α-tocopherol. The oxidations of β-apo-8′-carotenal and retinal under similar conditions were studied briefly, and the main products from the former compound were characterized. The initiation, the formation of the epoxides, the β-apo-carotenals and -carotenones, the successive chain shortening of the aldehydes to the ketones, and the formation of dihydroactinidiolide are explained in terms of free radical peroxidation chemistry.
- Mordi, Raphael C.,Walton, John C.,Burton, Graham W.,Hughes, Lise,Ingold U., Keith,Lindsay A., David,Moffatt J., Douglas
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p. 911 - 928
(2007/10/02)
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- Synthesis of (12,13-(13)C2)retinal and (13,14-(13)C2)retinal: a strategy to prepare multiple-(13)C-labeled conjugated systems
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(12,13-(13)C2)Retinal, (13,14-(13)C2)retinal, (19-(13)C)retinal and (20-(13)C)retinal (1) were prepared in a simple fashion in high yield via a consecutive strategy.The key step is the reaction of a N-methoxy-N-methylamide with an alkyllithium or a Grignard reagent.The preparation of the required N-methoxy-N-methylamide is discussed.In this scheme, only three commercially available (13)C-labeled starting materials (ethyl bromoacetate, acetonitrile and methyl iodide) are sufficient to construct retinals with any possible combination of (13)C labeling in the conjugated tail end.This strategy is applicable to the preparation of many other conjugated systems, such as retinoids, carotenoids and polyenes.
- Groesbeek, M.,Rood, G. A.,Lugtenburg, J.
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p. 149 - 154
(2007/10/02)
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- Exploratory study of β-carotene autoxidation
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The main products in the early stages of β-carotene autoxidation were epoxides, β-ionone, β-apo-13-carotenone, retinal, and related carbonyl compounds; in the final mixture short chain carbonyl compounds predominated.
- Mordi,Walton,Burton,Hughes,Ingold,Lindsay
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p. 4203 - 4206
(2007/10/02)
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- IODOTRIMETHYLSILANE DEOXYGENATION OF CARBONYL CONJUGATED ALLYLIC ETHERS
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The attempted demethylation of 4-methoxy-β-ionone (1) with iodotrimethylsilane gave the unexpected product, β-ionone (2).This reagent may prove useful in the cleavage of allylic ethers conjugated to ketones.
- Hartman, David A.,Curley, Robert W. Jr.
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p. 645 - 646
(2007/10/02)
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- Synthesis of retinals labelled with 13C in the cyclohexene ring
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In this paper we report the synthesis of five retinals, specifically mono-labelled with 13C at the positions 1,2,3 and 4 and di-labelled with 13 C at the positions 16 and 17, with more than 98percent chemical purity and high 13C incorporation. (1-13C)- and (16,17-13C2) retinal were obtained in 20percent overall yield from (2-13C)- and (1,3-13C2)acetone, (2-13C)- and (3-13C)retinal were prepared in 10percent overall yield from (1-13C)- and (2-13C)acetonitrile, while (4-13C)retinal was synthesized in 17percent overall yield starting from (2-13C)acetonitrile.
- Gebhard, R.,Courtin, J. M. L.,Shadid, J. B.,Haveren, J. van,Haeringen, C. J. van,Lugtenburg, J.
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p. 207 - 214
(2007/10/02)
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- Nickel-Catalyzed Oxidation of Allylic Alcohols with K2S2O8
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NiSO4-K2S2O8 has been found to be an efficient catalytic system for the selective oxidation of allylic alcohols to the corresponding unsaturated carbonyl compounds in excellent yields.
- Yamazaki, Shigekazu,Yamazaki, Yasuyuki
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p. 1361 - 1364
(2007/10/02)
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- TOTAL SYNTHESES OF (+/-)-β-IRONE
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The conversion of the product of the ene reaction of PhSOCl with geranyl acetate into racemic β-irone has been accomplished in seven steps, using high-pressure techniques for the olefination of β-methylcyclocitral.
- Moiseenkov, A. M.,Veselovskii, V. V.,Dragan, V. A.,Stashina, G. A.,Zhulin, V. M.
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p. 2394 - 2397
(2007/10/02)
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- CYCLIZATION OF ACYLIC ISOPRENOIDS. I. MOLECULAR REARRANGEMENT OF GERANYLACETONES AND PSEUDOIONONES IN SUPERACIDS
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Stable carbocations were generated for the first time from geranylacetones and pseudoionones.They are intermediate compounds both of the acid-catalyzed transformations of these substances and of new previously unknown molecular rearrangements.Experimentally supported mechanisms were proposed for the investigated reactions.It was shown that variation of the various factors (the structural characteristics of the initial substrates, the acidity of the medium, the ratio of the acid and the initial substance, the generation temperature, and the thawing temperature of theacidic solution) makes it possible to control the structural and stereochemical selectivity of the electrophilic cyclization of acyclic isoprenoids.
- Gavrilyuk, O. A.,Korchagina, D. V.,Gatilov, Yu. V.,Mamatyuk, V. I.,Osadchii, S. A.,et al.
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p. 411 - 434
(2007/10/02)
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- Synthesis and Absolute Stereochemistry of Chiral γ-Ionone and Dihydro-γ-ionone
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The optical resolution of (+/-)-α-cyclogeranic acid (4) with (-)-α-methylbenzylamine gave (-)-(S)-α-cyclogeranic acid (4).Epoxidation of (-)-(S)-methyl α-cyclogeranate (5), followed by reduction with lithium aluminium hydride, gave mainly (-)-(1R,2R)-2-hydroxy-2,6,6-trimethyl-1-cyclohexanemethanol (7b), which was oxidized with pyridinium chlorochromate to give (-)-hydroxyaldehyde 8.The reaction of aldehyde 8 with 2-oxopropylidenetriphenylphosphorane gave (-)-(1'S,2'R)-2',3'-dihydro-2'-hydroxy-α-ionone (9).The thermal decomposition of (1'S)-2'-acetoxy-2',3'-dihydro-α-ionone (10) gave (-)-(S)-α-ionone (2) and (+)-(S)-γ-ionone (1).The partial hydrogenation of (+)-(S)-γ-ionone (1) gave (+)-(S)-dihydro-γ-ionone (3).
- Oritani, Takayuki,Yamashita, Kyohei
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p. 1271 - 1276
(2007/10/02)
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- Synthesis of 8-, 9-, 12-, and 13-mono-13C-retinal
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The 8-, 9-, 12-, and 13-mono-13C-retinals were synthesized with >98percent chemical purity and 93percent 13C incorporation from 13C-labelled acetonitrile.Their 13C-13C and 13C-1H nmr coupling constants were determined.
- Pardoen, J. A.,Mulder, P. P. J.,Berg, E. M. M. van den,Lugtenburg, J.
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p. 1431 - 1435
(2007/10/02)
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