- METHOD FOR SYNTHESISING VITAMIN A
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A method for preparing dehydro-cyclofarnesal from dehydro-farnesal by cyclization in the presence of an acid may include the dehydro-farnesal being obtained from the farnesal by dehydrogenation and may further includes the cyclization being carried out in the presence of an acid selected from Lewis acids, Bronstedt acids, and zeolites. The synthesis of vitamin A using this method further includes the conversion of dehydro-cyclofarnesal into vitamin A.
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- Method for preparing vitamin A and vitamin A ester
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The invention provides a novel method for preparing vitamin A and vitamin A ester by taking farnesol as a raw material. The method comprises the following steps: carrying out oxidation reaction on farnesol and oxygen under the action of a catalyst and a cocatalyst to generate farnesal; carrying out dehydrogenation reaction on farnesal to generate dehydrofarnesal; carrying out cyclization reactionon the dehydrofarnesal under the catalysis of acid to generate a cyclized intermediate; carrying out a reaction on the cyclized intermediate with chloroisopentenol to generate vitamin A; carrying outan esterification reaction on vitamin A to generate vitamin A ester. The method avoids the defects of an existing process, and the process line is economical and effective.
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Paragraph 0061; 0064; 0067; 0070; 0073; 0076
(2020/04/17)
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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)
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- Synthetic control of retinal photochemistry and photophysics in solution
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Understanding how molecular structure and environment control energy flow in molecules is a requirement for the efficient design of tailor-made photochemistry. Here, we investigate the tunability of the photochemical and photophysical properties of the retinal-protonated Schiff base chromophore in solution. Replacing the n-butylamine Schiff base normally chosen to mimic the saturated linkage found in nature by aromatic amines results in the reproduction of the opsin shift and complete suppression of all isomerization channels. Modification of retinal by directed addition or removal of backbone substituents tunes the overall photoisomerization yield from 0 to 0.55 and the excited state lifetime from 0.4 to 7 ps and activates previously inaccessible reaction channels to form 7-cis and 13-cis products. We observed a clear correlation between the presence of polarizable backbone substituents and photochemical reactivity. Structural changes that increase reaction speed were found to decrease quantum yields, and vice versa, so that excited state lifetime and efficiency are inversely correlated in contrast to the trends observed when comparing retinal photochemistry in protein and solution environments. Our results suggest a simple model where backbone modifications and Schiff base substituents control barrier heights on the excited-state potential energy surface and therefore determine speed, product distribution, and overall yield of the photochemical process.
- Bassolino, Giovanni,Sovdat, Tina,Liebel, Matz,Schnedermann, Christoph,Odell, Barbara,Claridge, Timothy D.W.,Kukura, Philipp,Fletcher, Stephen P.
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supporting information
p. 2650 - 2658
(2014/03/21)
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- Base-induced decarboxylation of polyunsaturated α-cyano acids derived from malonic acid: Synthesis of sesquiterpene nitriles and aldehydes with β-, φ-, and ψ-end groups
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Catalytic base-induced decarboxylation of polyunsaturated α-cyano-β-methyl acids derived from malonic acid led to the corresponding nitriles 3 (Schemes 2 and 3), 6 (Scheme 5), and 9 (Scheme 6). This decarboxylation occurred with previous deconjugation of
- Dufossé, Laurent,Cartier, Dominique,Valla, Benoist,Fouillaud, Mireille,Labia, Roger,Valla, Alain
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p. 259 - 265
(2013/03/28)
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- A cross-metathesis approach to the synthesis of new etretinate type retinoids, ethyl retinoate and its 9Z-isomer
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Two aromatic retinoids were synthesized from styrene derivatives using a novel strategy with a cross-metathesis reaction as a key step. The biological activity of the new etretinate analogues was tested. Cross-metathesis reactions were also employed for the preparation of ethyl retinoate and its 9Z-isomer via the C15 + C5 route.
- Maj, Jadwiga,Morzycki, Jacek W.,Rárová, Lucie,Wasilewski, Grzegorz,Wojtkielewicz, Agnieszka
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supporting information
p. 5430 - 5433
(2012/11/07)
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- Syntheses of 13C2-labelled 11Z-retinals
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To enable solid-state NMR investigations of the rhodopsin chromophore and its photointermediates, a series of 11Z-retinal isotopomers have been synthesised containing pairs of adjacent 13C labels at C9/C10, C10/C11 or C11/C12, respectively. The C9 labelled carbon atom was introduced through the Heck reaction of a 13C-labelled Weinreb acrylamide derivative, and the label at the C12 position derived from a 13C-containing ethoxy Bestmann-Ohira reagent. The 13C labels at C10 and C11 were introduced through the reaction of β-ionone with labelled triethyl phosphonoacetate.
- McLean, Neville J.,Gansmuller, Axel,Concistre, Maria,Brown, Lynda J.,Levitt, Malcom H.,Brown, Richard C.D.
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p. 8404 - 8410
(2011/11/12)
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- Substituted Cyclohexadienals - Syntheses and Applications
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The present invention is generally directed to the use of L-proline and certain derivatives thereof to catalyze the asymmetric self-condensation of α,β-unsaturated aldehydes to form homodimer and heterodimer cyclohexadienals. Reaction conditions are mild
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Page/Page column 17
(2010/11/28)
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- New syntheses of retinal and its acyclic analog γ-retinal by an extended aldol reaction with a C6 building block that incorporates a C5 unit after decarboxylation. A formal route to lycopene and β-carotene
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Since the C15 β-end-group aldehyde 10 ((β-ionylidene) acetaldehyde), an excellent intermediate in the syntheses of retinoids, can be synthesized in many ways from β-ionone, and since the corresponding acyclic C15 ψ-end-group aldehyde 5 can easily be synthesized from citral (1) (Scheme 3), we applied the C15 + C5 route to the syntheses of γ-retinal ((all-E)-8) (Scheme 3) and retinal ((all-E)-13) (Scheme 4), and therefore, by coupling (2 x C20 → C 40), to the preparation of lycopene (14) and β-carotene (15) (Scheme 5). Our new syntheses of retinal ((all-E)-13) and γ-retinal ((all-E)-8 use an extended aldol reaction with a C6 building block that incorporates a C5 unit after decarboxylation.
- Valla, Alain,Valla, Benoist,Le Guillou, Regis,Cartier, Dominique,Dufosse, Laurent,Labia, Roger
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p. 512 - 520
(2008/02/07)
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- Synthesis and preliminary biological evaluation of β-carotene and retinoic acid oxidation products
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Synthesis of the β-carotene oxidation product, 2,3-dihydro-5,8-endoperoxy-β-apo-carotene-13-one (1) was achieved in six steps starting from β-ionone. Photo-oxygenation of all trans-retinoic acid (8) and 13-cis-retinoic acid (9) produced a mixture of 5S*,8
- Kithsiri Wijeratne,Liu, Manping X.,Kantipudi, Narendra B.,Brochini, Claudia B.,Leslie Gunatilaka,Canfield, Louise M.
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p. 7875 - 7879
(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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- An efficient commercial process for the preparation of isotretinoin
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We describe an efficient process for the preparation of isotretinoin (13-cis isomer of vitamin A acid) in a single step starting from β-ionylidene acetaldehyde (5). The process conditions are convenient to operate on a commercial scale and afford isotretinoin of excellent quality; levels of related isomeric impurities such as tretinoin (all trans retinoic acid) and 9,13-di-cis-retinoic acid are extremely low. Thus, condensation of dienolate of methyl 3,3-dimethylacrylate with β-ionylidene acetaldehyde (5) followed by aqueous acidic workup afforded isotretinoin in >95% purity. The condensation reaction proceeds via in situ formation of lactone (8); furthermore, the reaction conditions have been optimized to exploit in situ generated methoxide anion for lactone ring opening to afford the desired product. Distinct advantages of this process are that it does not require isolation of intermediate lactone and utilizes in situ generated methoxide for lactone ring opening, thus obviating the need for an additional step and base. We also describe an optimized process for the preparation of β-ionylidene acetaldehyde (5), a key intermediate for isotretinoin.
- Salman, Mohammad,Babu, Suresh J.,Kaul, Vijay K.,Ray, Purna C.,Kumar, Naresh
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p. 302 - 305
(2012/12/24)
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- 9-Demethyl-9-haloretinals by Wadsworth-Emmons coupling - Easy preparation of pure (all-E), (9Z) and (11Z) isomers
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5-(2′,6′,6′-Trimethyl-1′-cyclohexen-1′-yl) -4-penten-2-yn-1-al has been prepared in a one-pot process starting from β-ionone in almost quantitative yield. Using 1,4-nucleophilic addition reactions, the corresponding 9-Cl, 9-Br, 9-1 β-ionylideneacetaldehyde systems could be obtained in one step in quantitative yield as a mixture of (9Z) and (all-E) isomers. Even the corresponding fluoro derivative could be obtained in good yield as (9Z) and (all-E) isomers. In the case of a double bond having a halogen substituent, the IUPAC rules have the (E) nomenclature for a cis double bond and the (Z) for a trans double bond. Simple column chromatography gave the pure (9Z) and (all-E) form. Optimizing the Wadsworth-Emmons coupling gave the corresponding (all-E)- and (9Z)-retinonitriles in quantitative yield. Subsequent DIBAL-H reduction gave the corresponding retinals. For the preparation of the (UZ) isomers essential to vision, we found that Wadsworth-Emmons reactions with the diphenyl phosphonate group gave retinonitriles in quantitative yield, where the newly formed double bond is predominantly the (11Z) form (> 60%), together with the (9Z) isomer as minor component. The nitriles could be isolated in pure (9Z.11Z) and (9Z) forms by simple column chromatography. In the case of the (9Z,11Z)-9-demethyl-9-halo systems, a complication arose due to the unprecedented acid lability of these (9Z,11Z) aldehydes. By adjusting the DIBAL-H reduction workup procedure, these aldehydes are now available in pure form. We used this strategy to rationally synthesize (11Z)-retinal starting from β-cyclocitral as a first test for the generality of our new approach. β-Ionylideneacetaldehyde could be prepared in the (all-E) form in almost quantitative yield. Extending the conjugated chain of this molecule gave an almost quantitative yield of a mixture containing 80% (11Z)-retinal and 20% (all-E) as the minor component. Simple column chromatography gave pure (11Z)-retinal in 75% overall yield. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Wang, Yajie,Woo, Wei Sein,Van Der Hoef, Ineke,Lugtenburg, Johan
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p. 2166 - 2175
(2007/10/03)
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- Preparation and biological activity of 13-substituted retinoic acids
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13-Demethyl or 13-substituted all-E- and 9Z-retinoic acids were synthesized using a palladium-catalyzed coupling reaction of enol triflates and tributylstannylolefins. Their biological activities were then measured. The 13-ethyl analogs exhibited approximately one-half of the antiproliferative and differentiation-inducing activity of ATRA in HL-60 cells. In contrast, in the 9Z-derivatives, all analogs, except for the 13-butyl derivatives, showed apoptosis-inducing activity.
- Wada, Akimori,Fukunaga, Kouki,Ito, Masayoshi,Mizuguchi, Yukari,Nakagawa, Kimie,Okano, Toshio
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p. 3931 - 3942
(2007/10/03)
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- Synthesis of 10,11,14,15-13C4- and 14,15-13C2-retinyl acetate
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The synthesis of 10,11,14,15-13C4- and 14,15-13C2-retinyl acetate is described. The procedure uses a modified Wittig-Horner synthesis. By using the 13C isotope, sensitive gas chromatography-combustion
- Tanumihardjo, Sherry A.
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p. 365 - 372
(2007/10/03)
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- A Novel Method for a Stereoselective Synthesis of Trisubstituted Olefin Using Tricarbonyliron Complex: A Highly Stereoselective Synthesis of (all-E)- and (9Z)-Retinoic Acids
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In order to establish the stereoselective synthesis of retinoic acids, which are ligand molecules of the retinoic acid receptors (RARs, all-E-isomer) and the retinoid X receptors (RXRs, 9Z-isomer), the reaction of β-ionone-tricarbonyliron complex 7 with carbanions was investigated. Treatment of 7 with the lithium salt of acetonitrile afforded (7E,9E)-β-ionylideneacetonitrile-tricarbonyliron complex 8 exclusively, via addition, dehydration, and migration of tricarbonyliron complex. On the contrary, the reaction of 7 with the lithium enolate of ethyl acetate and subsequent dehydration by thionyl chloride afforded the ethyl (7E,9Z)-β-ionylideneacetate-tricarbonyliron complex 16b predominantly. These compounds (8 and 16b) were converted to the corresponding β-ionylidene-acetaldehyde-tricarbonyliron complexes (10 and 22) in excellent yields, respectively. The Emmons-Horner reaction of these compounds with C5-phosphonate followed by the sequence of decomplexation and alkaline hydrolysis gave the corresponding retinoic acids (26 and 29).
- Wada, Akimori,Hiraishi, Saeko,Takamura, Norio,Date, Tadamasa,Aoe, Keiichi,Ito, Masayoshi
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p. 4343 - 4348
(2007/10/03)
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- Stereoselective synthesis of 7E,9E- and 7E,9Z-β-ionylidene-acetaldehydes by use of tricarbonyl iron complex
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Stereoselective synthesis of 7E,9E- and 7E,9Z-β-ionylideneacetaldehydes was accomplished from the β-ionone tricarbonyl iron complex, and the latter was converted to 9Z-retinoic acid.
- Wada,Hiraishi,Ito
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p. 757 - 759
(2007/10/02)
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- Synthesis of High Specific Activity -9-cis-Retinoic Acid and Its Application for Identifying Retinoids with Unusual Binding Properties
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all-trans-Retinoic acid is known to bind to the retinoic acid receptors (RARs) resulting in an increase in their transcriptional activity.In contrast, recently identified 9-cis-retinoic acid (9-cis-RA), which is an additional endogenous RA isomer, is capable of binding to both RARs and retinoid X receptors (RXRs).These distinct properties have raised questions as to the biological role governed by these two retinoic acid isomers and the set of target genes that they regulate.Herein, we report the synthesis of high specific activity -9-cis-RA and its application to study the ligand-binding properties of the various retinoid receptor subtypes.We examined the binding properties of RARs and RXRs for a series of synthetic retinoids and compared the ligand-binding properties of these arotinoid analogs with their ability to regulate gene expression via the retinoid receptors in a cotransfection assay.The utilization of the -9-cis-RA competitive binding assay and the cotransfection assay has made it possible to rapidly identify important structural features of retinoids leading to increased selectivity for either the RAR or RXR receptor subtypes.
- Boehm, Marcus F.,McClurg, Michael R.,Pathirana, Charles,Mangelsdorf, David,White, Steven K.,et al.
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p. 408 - 414
(2007/10/02)
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- The OSM (Oxidation State Modification) Concept: Application to a New and Rapid Synthesis of Retinoids
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The OSM (oxidation state modification) concept for the elaboration of new synthetic pathways is demonstrated for the synthesis of β-ionylidene acetaldehyde 11 and retinal 13.According to this new scheme, electrophilic addition to ω-heterosubstituted enol ethers 5 of the cationic species 9, generated from β-ionol led to aldehydic intermediates 10 which undergo easy elimination to β-ionylidene acetaldehyde 11.Similarly, retinal 13 was obtained from vinyl-β-ionol 14 and dienol ethers 12, via aldehydes 16.
- Duhamel, Lucette,Duhamel, Pierre,Ancel, Jean-Erick
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p. 1209 - 1210
(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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- Polyvinylogation Reagents: 1-Lithio-4-trimethylsiloxy-penta-1,3-diene and 1-Lithio-4-ethoxy-2-methyl-buta-1,3-diene
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Title products, lithiodienol ethers 6a and 7a, synthetic equivalents of 4-lithio pent-3-ene-2-one and 4-lithio-senecialdehyde were obtained by bromine-lithium exchange.They are choice reagents for the transformations 1 -> 2 and 1 -> 3, respectively.
- Duhamel, Lucette,Ancel, Jean-Erick
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p. 9237 - 9250
(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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- Dependence of the Triplet Potential of Retinal Homologues on the Chain Length: Resonance Raman Spectroscopy and Analysis of Triplet-Sensitized Isomerization
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The Raman spectra of triplet species produced from the all-trans, 7-cis and 9-cis isomers of β-ionylideneacetaldehyde (C15 aldehyde) and of β-ionylidenecrotonaldehyde (C17 aldehyde) were recorded.Each isomer of C15 aldehyde showed its own triplet Raman spectrum, while all the isomers of C17 aldehyde showed an identical triplet spectrum.The results were compared with those of isomeric retinal (C20 aldehyde) and retinylideneacetaldehyde (C22 aldehyde) obtained previously.Triplet-sensitized isomerization as well as direct photoisomerization of the all-trans isomer and the complete set of mono-cis isomers of C15, C17, C20, and C22 aldehydes were analyzed by HPLC.Mutual isomerization among the all-trans was seen for C17, C20, and C22 aldehydes.The quantum yield of triplet-sensitized isomerization for each isomer of the above aldehydes was determined. all the results are discussed in terms of triplet potentials with minima at cis and trans positions, the relative stability being dependent on the length of the polyene chain; the cis minima are as stable as the trans minimum for C15 aldehyde, while the cis minima are far less stable than the trans minimum for C17, C20, and C22 aldehydes.
- Mukai, Yumiko,Hashimoto, Hideki,Koyama, Yasushi
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p. 4042 - 4051
(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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- SYNTHETIC INVESTIGATIONS IN THE CHEMISTRY OF POLYENE COMPOUNDS. -- XLVIII. STRUCTURE AND TRANSFORMATIONS OF 12-CARBOXYRETINOIC ACIDS AND THEIR ESTERS. SYNTHESIS OF 13-CIS-RETINOIC ACID
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In reaction with ethyl β-methylglutaconate under the influence of alkali in methanol the Z and E isomers of β-ionylideneacetaldehyde form isomeric 9Z,11Z,13Z- and 9E,11Z,13Z-12-carboxyretinoic acids.Decarboxylation of the latter in the pyridine-piperidine system in the presence of copper salts leads to 13Z-retinoic acid and is accompanied by the formation of 9,13-dimethyl-7-(1,1,5-trimethyl-5-cyclohexen-6-yl)-7,9,11,13-octatetraene.The stereoisomeric transformations of 12-substituted 9E,Z,11Z,13Z-retinoic acids and the corresponding diols and diacetates obtained from them were investigated.Isomerization takes place at the double bond at the C9 atom and depends on the nature of the substituent at the C12 atom.
- Polyachenko, L. N.,Davydova, L. P.,Darskaya, E. N.,Filippova, T. M.,Samokhvalov, G. I.
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p. 685 - 694
(2007/10/02)
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- ELECTRO-ORGANIC REACTIONS. PART 25. THE ROLE OF CHROMIUM(III) IN THE MODIFICATION OF CATHODIC PINACOLISATION
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The presence of chromium(III) chloride, both hydrated and anhydrous, profoundly alters the course of cathodic in dimethylformamide solutions of benzophenone, benzaldehyde, β-ionone, β-ionylidene acetaldehyde, and retinal.Pinacolisation is enhanced at the expense of formation of the corresponding alcohol.Furthermore the relevant reduction potential is lowered.The mechanism of the reaction has been investigated using voltammetric and coulometric experiments combined with a detailed analysis of preparative-scale reductions under a variety of conditions.The stereochemical course of the reactions has also been considered.In total the results provide compelling evidence in favour of the key reducible intermediate being a carbonyl compound-Cr(III) complex which is formed via the corresponding Cr(III) species with homogenous, inner sphere, re-oxidation playing a crucial role.This is contrary to earlier suggestions invoking the participation of electrogenerated Cr(II) as the reductant.
- Sopher, David W.,Utley, James H. P.
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p. 1361 - 1368
(2007/10/02)
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- 4-(Dimethylamino)pyridinium Chlorochromate, a New Selective Reagent for the Oxidation of Allylic and Benzylic Alcohols
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4-(Dimethylamino)pyridinium chlorochromate (3) is a mild selective reagent for the oxidation of complex allylic and benzylic alcohols to the corresponding carbonyl compounds.
- Guziec, Frank S.,Luzzio, Frederick A.
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p. 1787 - 1789
(2007/10/02)
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- On the photoisomerisation of 13-desmethyl-retinal
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All mono-cis-isomers of 13-desmethyl-retinal have been prepared fro the alll-trans-compound by photoisomerisation. The various isomers were separated by HPLC and identified by their 400 MHz-1NMR-spectra.
- Gaertner, Wolfgang,Hopf, Henning,Hull, William E.,Oesterhelt, Dieter,Scheutzow, Dieter,Towner, Paul
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p. 347 - 350
(2007/10/02)
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