- 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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- Synthesis of C40-symmetrical fully conjugated carotenoids by olefin metathesis
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In an effort to push olefin metathesis to the limits of conjugation in reactants and products, the C40-symmetrical carotenoids β,β-carotene (1), lycopene (2), (3R,3′R)-zeaxanthin (3), and rac-isozeaxanthin (4), which are conjugated undecaenes, have been synthesized from C21-terminal hexaenes by treatment with Grubbs' second-generation Ru catalyst in dichloromethane at 50 °C.
- Fontan, Noelia,Dominguez, Marta,Ulvarez, Rosana,De Lera, Ungel R.
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experimental part
p. 6704 - 6712
(2012/01/03)
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- Nucleophilic reactions of charge delocalised carotenoid mono- and dications
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In the present study insight was gained on the larger complexity of cationic mixtures of diaryl (φ,φcarotene, isorenieratene) and aliphatic (Φ,Φ-carotene, lycopene) carotenes, prepared by reaction with BF 3-etherate, compared with β,β-carotene. Chemical reactions of the mono- and dications prepared in situ from the allylic carotenols β,β-caroten-4-ol (isocryptoxanthin) and β,β-carotene-4,4'- diol (isozeaxanthin), and from isorenieratene and lycopene were investigated using selected O, N and S nucleophiles; water, methanol, azide and thioacetate. In total 22, including 18 new, neutral carotenoid products were isolated and identified by VIS, MS and NMR (in part) spectroscopy. Their structures were compatible with the structures of the cationic intermediates. The formal addition of hydride to the various dications, required to rationalise minor reaction products, is discussed in terms of more likely hydrogen radical or proton transfer in cationic reactions. Extensive E/Z isomerisation was observed for all quenching products. The potential use of carotenoid cations for the synthesis of 4,(4')-substituted β,β-carotenes and 7-oxabicycloheptane derivatives is discussed.
- Kildahl-Andersen, Geir,Bruas, Liv,Lutnaes, Bjart Frode,Liaaen-Jensen, Synnove
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p. 2496 - 2506
(2007/10/03)
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- Selective hydrogenation of carotenones II.? Reduction of rhodoxanthin to lutein and zeaxanthin, and of canthaxanthin to a dihydro-retro-carotenediol by tellurium hydride
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Racemic lutein and racemic zeaxanthin have been prepared from rhodoxanthin by reduction with tellurium hydride. Similarly, canthaxanthin was transformed into a retro-carotenediol. Acta Chemica Scandinivica 1996.
- Sliwka, Hans-Richard,Liaaen-Jensen, Synnove
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p. 637 - 639
(2007/10/03)
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- Electronic Relaxation in Long Polyenes
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A series of carotenols with from 7 to 11 conjugated double bonds have been synthesized and purified using HPLC techniques.Absorption, fluorescence, and fluorescence excitation spectra have been obtained in 77 K glasses.The shorter members of this series e
- Cosgrove, Sarah A.,Guite, Melissa A.,Burnell, Timothy B.,Christensen, Ronald L.
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p. 8118 - 8124
(2007/10/02)
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- Synthetic Sulfur Carotenoids: 3'-Thiolutein
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Partial syntheses of the title compound via its S-acetyl derivative and of the S-acetyl derivative of (4'RS)-4'-mercapto-β,β-caroten-4-one are described.
- Sliwka, Hans-Richard,Liaaen-Jensen, Synnove
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- Determination of Enantiomeric Composition of Partly Racemized Carotenols
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Method for determining enantiomeric composition of various racemized carotenols by converting them into diastereomeric esters with subsequent analysis have been studied.Diastereomeric esters of (-)-camphanic acid with carotenols other than α-ketols could not be separated by HPLC.No separation was achieved for diastereomeric esters of methoxytrifluoromethylphenylacetic acid (MTPA). 1H NMR analysis in the presence of Eu(fod)3 of diastereomeric MTPA esters allowed quantitative determination of the enantiomeric composition of carotenols with 2-hydroxy-β- and 3-hydroxy-β-type end groups.
- Aareskjold, Kare,Liaaen-Jensen, Synnove
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p. 499 - 504
(2007/10/02)
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