- Process or synthesis of (3S)- and (3R)-3-hydroxy-beta-ionone, and their transformation to zeaxanthin and beta-cryptoxanthin
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Disclosed is a process for the synthesis of (3R)-3-hydroxy-β-ionone and its (3S)-enantiomer in high optical purity from commercially available (rac)-α-ionone. The key intermediate for the synthesis of these hydroxyionones is 3-keto-α-ionone ketal that was prepared from (rac)-α-ionone after protection of this ketone as a 1,3-dioxolane. Reduction of 3-keto-α-ionone ketal followed by deprotection, lead to 3-hydroxy-α-ionone that was transformed into (rac)-3-hydrox-β-ionone by base-catalyzed double bond isomerization in 46% overall yield from (rac)-α-ionone. The racemic mixture of these hydroxyionones was then resolved by enzyme-mediated acylation in 96% ee. (3R)-3-Hydroxy-β-ionone and its (3S)-enantiomer were respectively transformed to (3R)-3-hydroxy-(β-ionylideneethyl)triphenylphosphonium chloride [(3R)-C15-Wittig salt] and its (3S)-enantiomer [(3S)-C15-Wittig salt] according to known procedures. Double Wittig condensation of these Wittig salts with commercial available 2,5- dimethtylocta-2,4,6-triene-1,8-dial provided all 3 stereoisomers of zeaxanthin. Similarly, (3R)-C15-Wittig and its (3S)-enantiomer were each coupled with β-apo-12′-carotenal.
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- Synthesis of (3S)- and (3R)-3-hydroxy-β-ionone and their transformation into (3S)- and (3R)-β- cryptoxanthin
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(3S)- and (3R)-3-Hydroxy-β-ionone and (3S)- and (3R)-3-Hydroxy-β- ionone synthesized in high enantiomeric purity from commercially available () - ionone. These ionones were then transformed into (3R) - cryptoxanthin and (3S) - cryptoxanthin by a C15+C10+C15 Wittig coupling strategy according to known methods. This methodology can considerably simplify the total synthesis of optically active carotenoids with 3-hydroxy - end groups that possess significant biological activities. Georg Thieme Verlag Stuttgart New York.
- Khachik, Frederick,Chang, An-Ni
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p. 509 - 516
(2011/04/16)
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- Synthesis of zeaxanthin- and cryptoxanthin-β-D-glucopyranosides
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β-Glucosidation of (3R)-3-hydroxy-β-ionone (6) was achieved in a reasonable yield by use of tetra-O-benzoyl-α-D-glucopyranosyl bromide (8 c) as a glycosyl donor and silver triflate as an activator. The resulting glucoside (9) was transformed into the β-apo-12'-carotenal (18), which was condensed with the Wittig salt (19) or (20) to provide zeaxanthin-mono-β-D- glucopyranoside (3) or cryptoxanthin-β-D-glucopyranoside (4).
- Yamano, Yumiko,Sakai, Yoshitsugu,Yamashita, Satomi,Ito, Masayoshi
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p. 141 - 146
(2007/10/03)
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