472-61-7

Synthetic route

(2E,4E,6E)-2,7-dimethyl-2,4,6-octatrienedial (5056-17-7) + <5-((S)-4-Hydroxy-2,6,6-trimethyl-3-oxo-1-cyclohexen-1-yl)-3-methyl-2,4-pentadienyl>triphenylphosphoniumbromid → (3S,3'S)-astaxanthin (472-61-7) + (3R,3'S)-3,3′-dihydroxy-β,β′-caroten-4,4′-dione (71772-51-5)

Conditions	Yield
With sodium methylate In methanol at 0 - 25℃; for 4h;	A 94.6% B 4.2 % Chromat.
In various solvent(s) for 20h; Heating;	A 97.7 % Chromat. B 2.1 % Chromat.

C12H20O4 (696647-73-1) + [(4E)-5-(4-hydroxy-2,6,6-trimethyl-3-oxo-1-cyclohexen-1-yl)-3-methyl-2,4-pentadienyl]-triphenylphosphonium bromide → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Stage #1: C12H20O4; [(4E)-5-(4-hydroxy-2,6,6-trimethyl-3-oxo-1-cyclohexen-1-yl)-3-methyl-2,4-pentadienyl]-triphenylphosphonium bromide With sodium methylate In methanol at 0℃; for 2h; Wittig Reaction; Stage #2: With acetic acid In methanol; water at 20 - 75℃; for 20h; Heating / reflux;	83%

(3S,3'S)-Astaxanthin-di-(-)-camphanat → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
With sodium hydroxide In methanol; dichloromethane for 1.16667h; Ambient temperature;	73%

(2E,4E,6E)-2,7-dimethyl-2,4,6-octatrienedial (5056-17-7) + <5-((S)-4-Hydroxy-2,6,6-trimethyl-3-oxo-1-cyclohexen-1-yl)-3-methyl-2,4-pentadienyl>triphenylphosphoniumbromid → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
	70.7%

(2E,4E,6E)-2,7-dimethyl-2,4,6-octatrienedial (5056-17-7) + [(2E,4E)-3-Methyl-5-((S)-2,6,6-trimethyl-3-oxo-4-phenoxymethoxycarbonyl-cyclohex-1-enyl)-penta-2,4-dienyl]-triphenyl-phosphonium; bromide → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
With sodium hydride In dichloromethane; isopropyl alcohol

(3S,3'S)-astaxanthin disulfate → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
With hydrogenchloride In methanol at 40℃;

3,4,3',4'-tetrahydroxy-β,β-carotene (6094-35-5, 28082-20-4) → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
With 2,3-dicyano-5,6-dichloro-p-benzoquinone In 1,4-dioxane

(S)-6-Hydroxy-3-(5-hydroxy-3-methyl-1,3-pentadienyl)-2,4,4-trimethyl-2-cyclohexen-1-on → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Multi-step reaction with 3 steps 1: aq. HBr / CH2Cl2 / 0.17 h / 0 °C 3: 94.6 percent / NaOMe / methanol / 4 h / 0 - 25 °C View Scheme

(S)-3-((1E,3E)-5-Bromo-3-methyl-penta-1,3-dienyl)-6-hydroxy-2,4,4-trimethyl-cyclohex-2-enone → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Multi-step reaction with 2 steps 2: 94.6 percent / NaOMe / methanol / 4 h / 0 - 25 °C View Scheme

3,3'-dihydroxy-β,β-carotene-4,4'-dione (7542-45-2) → (3S,3'S)-astaxanthin (472-61-7) + (3R,3'R)-3,3′-dihydroxy-β,β′-caroten-4,4′-dione (60760-95-4) + (3R,3'S)-3,3′-dihydroxy-β,β′-caroten-4,4′-dione (71772-51-5)

Conditions	Yield
Resolution of racemate;

(S)-2,7,11-trimethyl-13-(4-hydroxy-2,6,6-trimethyl-3-oxo-1-cyclohexen-1-yl)-2,4,6,8,10,12-tridecahexaen-1-al (72523-68-3) → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
In ethanol for 3h; Heating / reflux;

astaxanthin radical-cation → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
With daidzein dianion In methanol; chloroform at 25℃; Thermodynamic data; Kinetics; Reagent/catalyst;

(4S)-4-acetoxy-3-oxo-1-(3-oxo-1-butenyl)-2,6,6-trimethyl-1-cyclohexene → (3S,3'S)-astaxanthin (472-61-7)

Conditions

Yield

Multi-step reaction with 5 steps 1.1: E-2 / aq. phosphate buffer; acetone / 1 h / 20 - 30 °C / pH 7 / Large scale; Enzymatic reaction 2.1: pyridinium p-toluenesulfonate / toluene / 0.5 h / -5 - 5 °C / Large scale 3.1: tetrahydrofuran / 2 h / -75 - -55 °C / Large scale 4.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 5.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 5.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme

(4S)-4-hydroxy-3-oxo-1-(3-oxo-1-butenyl)-2,6,6-trimethyl-1-cyclohexene → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Multi-step reaction with 4 steps 1.1: pyridinium p-toluenesulfonate / toluene / 0.5 h / -5 - 5 °C / Large scale 2.1: tetrahydrofuran / 2 h / -75 - -55 °C / Large scale 3.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 4.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 4.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme

(4S)-4-(2-methoxypropan-2-yloxy)-3-oxo-1-(3-oxo-1-butenyl)-2,6,6-trimethyl-1-cyclohexene → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Multi-step reaction with 3 steps 1.1: tetrahydrofuran / 2 h / -75 - -55 °C / Large scale 2.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 3.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 3.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme

1-(3-hydroxy-3-methyl-1,4-pentadienyl)-(4S)-4-(2-methoxypropan-2-yloxy)-3-oxo-2,6,6-trimethyl-1-cyclohexene → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Multi-step reaction with 2 steps 1.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 2.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 2.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme

(2E,4E,6E)-2,7-dimethyl-2,4,6-octatrienedial (5056-17-7) + 1-(5-bromo-3-methyl-1,3-pentadienyl)-(4S)-4-hydroxy-3-oxo-2,6,6-trimethyl-1-cyclohexene → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Stage #1: 1-(5-bromo-3-methyl-1,3-pentadienyl)-(4S)-4-hydroxy-3-oxo-2,6,6-trimethyl-1-cyclohexene With ethyloxirane; triphenylphosphine In ethyl acetate at 0 - 30℃; for 24h; Large scale; Stage #2: (2E,4E,6E)-2,7-dimethyl-2,4,6-octatrienedial With ethyloxirane; 2,6-di-tert-butyl-4-methyl-phenol In isopropyl alcohol for 30h; Reflux; Inert atmosphere; Large scale;	1.53 kg

2-[2-((4RS)-4-acetoxy-3-oxo-2,6,6-trimethyl-1-cyclohexenyl)vinyl]-2-methyl-1,3-dioxolane → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Multi-step reaction with 7 steps 1.1: LAY 400-AF / aq. phosphate buffer; toluene / 24 h / 37 °C / pH 7 / Enzymatic reaction 1.2: 3 h / 50 °C 2.1: hydrogenchloride / toluene; methanol; water / 2 h / 20 - 30 °C 3.1: E-2 / aq. phosphate buffer; acetone / 1 h / 20 - 30 °C / pH 7 / Large scale; Enzymatic reaction 4.1: pyridinium p-toluenesulfonate / toluene / 0.5 h / -5 - 5 °C / Large scale 5.1: tetrahydrofuran / 2 h / -75 - -55 °C / Large scale 6.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 7.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 7.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme
Multi-step reaction with 7 steps 1.1: LAY 400-AF / aq. phosphate buffer; toluene / 24 h / 37 °C / pH 7 / Enzymatic reaction 2.1: hydrogenchloride / toluene; methanol; water / 2 h / 20 - 30 °C 3.1: E-2 / aq. phosphate buffer; acetone / 1 h / 20 - 30 °C / pH 7 / Large scale; Enzymatic reaction 4.1: pyridinium p-toluenesulfonate / toluene / 0.5 h / -5 - 5 °C / Large scale 5.1: tetrahydrofuran / 2 h / -75 - -55 °C / Large scale 6.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 7.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 7.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme

2-[2-((4S)-4-acetoxy-3-oxo-2,6,6-trimethyl-1-cyclohexenyl)vinyl]-2-methyl-1,3-dioxolane → (3S,3'S)-astaxanthin (472-61-7)

Conditions

Yield

Multi-step reaction with 6 steps 1.1: hydrogenchloride / toluene; methanol; water / 2 h / 20 - 30 °C 2.1: E-2 / aq. phosphate buffer; acetone / 1 h / 20 - 30 °C / pH 7 / Large scale; Enzymatic reaction 3.1: pyridinium p-toluenesulfonate / toluene / 0.5 h / -5 - 5 °C / Large scale 4.1: tetrahydrofuran / 2 h / -75 - -55 °C / Large scale 5.1: hydrogen bromide / dichloromethane / 0.5 h / -21 - -11 °C / Large scale 6.1: triphenylphosphine; ethyloxirane / ethyl acetate / 24 h / 0 - 30 °C / Large scale 6.2: 30 h / Reflux; Inert atmosphere; Large scale View Scheme

canthaxanthin (514-78-3) → (3S,3'S)-astaxanthin (472-61-7)

Conditions	Yield
Stage #1: canthaxanthin With iodosylbenzene; sodium hydroxide In methanol at 10 - 20℃; for 12.5h; Inert atmosphere; Stage #2: With sulfuric acid In water at 20℃; for 5h; Reagent/catalyst; Temperature; Solvent;	4.48 g

(3S,3'S)-astaxanthin (472-61-7) + n-hexadecanoyl chloride (112-67-4) → astaxanthin dipalmitate (5794-22-9) + (6S)-6-palmitoyloxy-3-[(all-E)-18-[(4S)-4-hydroxy-2,6,6-trimethyl-3-oxo-1-cyclohexenyl]-3,7,12,16-tetramethyloctadeca-1,3,5,7,9,11,13,15,17-nonaenyl]-2,4,4-trimethyl-1-cyclohex-2-enone

Conditions	Yield
With pyridine In dichloromethane for 5h; Concentration;	A 92.48% B 0.63%

(3S,3'S)-astaxanthin (472-61-7) + C16H23ClO3Si → astaxanthin diferulate

Conditions	Yield
Stage #1: (3S,3'S)-astaxanthin; C16H23ClO3Si With pyridine In dichloromethane at 0 - 20℃; Inert atmosphere; Stage #2: With caesium carbonate In water; N,N-dimethyl-formamide for 2h; Inert atmosphere;	80%

(3S,3'S)-astaxanthin (472-61-7) + Stearoyl chloride (112-76-5) → astaxanthin dioctadecanoate (173422-82-7)

Conditions	Yield
With pyridine In dichloromethane at 20℃;	80%

(3S,3'S)-astaxanthin (472-61-7) + n-hexadecanoyl chloride (112-67-4) → astaxanthin dipalmitate (5794-22-9)

Conditions	Yield
With pyridine In dichloromethane at 20℃; Concentration; Reagent/catalyst; Temperature; Solvent;	73%
With pyridine

n-dodecanoyl chloride (112-16-3) + (3S,3'S)-astaxanthin (472-61-7) → astaxanthin didodecanoate

Conditions	Yield
With pyridine In dichloromethane at 20℃;	73%

(3S,3'S)-astaxanthin (472-61-7) + n-decanoyl chloride (112-13-0) → [(1S)-4-[(1E,3E,5E,7E,9E,11E,13E,15E,17E)-18-[(4S)-4-decanoyloxy-2,6,6-trimethyl-3-oxocyclohexen-1-yl]-3,7,12,16-tetramethyloctadeca-1,3,5,7,9,11,13,15,17-nonaenyl]-3,5,5-trimethyl-2-oxocyclohex-3-en-1-yl] decanoate

Conditions	Yield
With pyridine In dichloromethane at 20℃;	69%

(3S,3'S)-astaxanthin (472-61-7) + benzoic acid (65-85-0) → 4,4'-dioxo-β,β-carotene-3,3'-diyl dibenzoate

Conditions	Yield
With Novozyme 435 In methanol; toluene at 37℃; for 6h; Darkness; Enzymatic reaction;	59%

(3S,3'S)-astaxanthin (472-61-7) + p-Toluic acid (99-94-5) → 4,4'-dioxo-β,β-carotene-3,3'-diyl di(4-methylbenzoate)

Conditions	Yield
With Novozyme 435 In methanol; toluene at 37℃; for 6h; Darkness; Enzymatic reaction;	58%

nicotinic acid (59-67-6) + (3S,3'S)-astaxanthin (472-61-7) → 4,4'-dioxo-β,β-carotene-3,3'-diyl di(pyridine-3-carboxylate)

Conditions	Yield
With Novozyme 435 In methanol; toluene at 37℃; for 6h; Darkness; Enzymatic reaction;	57%

(3S,3'S)-astaxanthin (472-61-7) + 4-Nitrophenyl chloroformate (7693-46-1) → C54H58N2O12

Conditions	Yield
Stage #1: (3S,3'S)-astaxanthin With n-butyllithium In tetrahydrofuran at -70℃; for 0.25h; Stage #2: 4-Nitrophenyl chloroformate In tetrahydrofuran at 20℃; for 8h;	56.1%

(3S,3'S)-astaxanthin (472-61-7) + MANDELIC ACID (611-71-2, 611-72-3, 17199-29-0, 90-64-2) → 4,4'-dioxo-β,β-carotene-3,3'-diyl di(2-hydroxy-2-phenylethanoate)

Conditions	Yield
With Novozyme 435 In methanol; toluene at 37℃; for 6h; Darkness; Enzymatic reaction;	55%

(3S,3'S)-astaxanthin (472-61-7) + (3R,3'R)-3,3′-dihydroxy-β,β′-caroten-4,4′-dione (60760-95-4) + (3R,3'S)-3,3′-dihydroxy-β,β′-caroten-4,4′-dione (71772-51-5) + N-(all-trans-Retinoyl)-imidazole (61319-45-7) → astacene (34026-74-9, 58769-83-8) + (3R,3'S)-astaxanthin monoretinoate

Conditions	Yield
With pyridine; sodium hydride at 20℃; for 3h;	A 50% B 5%

β-1-bromo-2,3,4,6-tetra-O-benzoyl-α-D-glucopyranoside (114682-36-9, 14218-11-2, 14218-30-5, 61198-88-7, 108438-33-1, 108836-02-8, 127305-34-4, 151377-77-4) + (3S,3'S)-astaxanthin (472-61-7) → C108H104O22 (1010099-33-8)

Conditions	Yield
With 4 A molecular sieve; silver trifluoromethanesulfonate In dichloromethane at 0℃; for 2h;	31%

(3S,3'S)-astaxanthin (472-61-7) → 9-Z-3,3′-dihydroxy-4,4′-dione-β,β′-carotene + 13-Z-3,3′-dihydroxy-4,4′-dione-β,β′-carotene

Conditions	Yield
With iodine-doped titanium dioxide In ethyl acetate at 70℃; for 2h; Reagent/catalyst; Temperature; Solvent;	A 22.7% B 16.9%
In acetone; Petroleum ether at 70℃; for 12h;
With I-TiO2 In ethyl acetate at 70℃; for 2h;

(3S,3'S)-astaxanthin (472-61-7) + (E)-2-((3-(thiazolidin-3-yl)propyl)imino)acetic acid → C48H64N2O5S + C56H76N4O6S2

Conditions	Yield
With benzotriazol-1-ol; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; triethylamine In dichloromethane at 20℃; for 48h;	A 10.9% B 15.7%

(3S,3'S)-astaxanthin (472-61-7) → (3S,3'S)-15,15'-cis-Astaxanthin

Conditions	Yield
With hydrogen; Lindlar's catalyst In dichloromethane

(3S,3'S)-astaxanthin (472-61-7) + (-)-methoxytrifluoromethylphenylacetyl chloride (39637-99-5) → C60H66F6O8 (84432-72-4, 84518-14-9, 84518-16-1)

Conditions	Yield
With pyridine at 0℃; for 0.75h; determination of enantiomeric composition of partly racemized carotenols by converting them in to diastereomeric esters, HPLC and NMR (in the presence of Eu(fod)3 shift reagent) analysis;

(3S,3'S)-astaxanthin (472-61-7) + (-)-camphanic acid chloride (39637-74-6, 104530-16-7) → C60H76O10

Conditions	Yield
With pyridine at 0℃; for 0.666667h;

(3S,3'S)-astaxanthin (472-61-7) → 3,4,3',4'-tetrahydroxy-β,β-carotene (6094-35-5, 28082-20-4)

Conditions	Yield
With sodium tetrahydroborate In ethanol

(3S,3'S)-astaxanthin (472-61-7) → (3S,3'S)-astaxanthin monosulfate + (3S,3'S)-astaxanthin disulfate

Conditions	Yield
With pyridine; chlorosulfonic acid for 2.5h; Ambient temperature; Yield given;

Upstream product

• 6094-35-5 3,4,3',4'-tetrahydroxy-β,β-carotene 
• 514-78-3 canthaxanthin 
• 5056-17-7 (2E,4E,6E)-2,7-dimethyl-2,4,6-octatrienedial 
• 83020-74-0 (7AS)-7,7a-dihydro-2,2,4,6,6-pentamethyl-1,3-benzodioxol-5-(6H)-one 
• 164293-05-4 2-methyl-4-bromo-2-butenal dimethyl acetal 
• 31516-35-5 4-bromo-2-methyl-2-butene-1-al 
• 5056-17-7 2,7-dimethyl-2,4,6-octanetriene-1,8-dialdehyde 
• 84592-32-5 3-methyl-5-(2,6,6-trimethyl-4-hydroxy-1-cyclohexene-3-carbonyl)-2,4-pentadiene-1-bromotriphenylphosphine 

Downstream Products

• 1010099-33-8 C₁₀₈H₁₀₄O₂₂ 
• 6094-35-5 3,4,3',4'-tetrahydroxy-β,β-carotene 
• 5794-22-9 astaxanthin dipalmitate 
• 173422-82-7 astaxanthin dioctadecanoate 

Relevant academic research and scientific papers

Beitrag zur Analytik und Synthese von 3-Hydroxy-4-oxocarotinoiden

(3RS,3'RS)-Astaxanthin (=3,3'-dihydroxy-β,β-carotene-4,4'-dione, 1:1-mixture of racemate and meso-form; 1) can be separated into its optical isomers (3S,3'S)-1a, (3R,3'R)-1b and meso-(3R,3'S)-1c via the corresponding diastereomeric di-(-)-camphanates.Some aspects of the configurational stability of astaxanthin are discussed. - HPLC. analysis of the (-)-camphanates of 3-hydroxy-4-oxocarotenoids provides, in suitable cases and supported by spectroscopic data, an analytical method for the simultaneous determination of constitution and chiralty.

Synthetic method of astaxanthin

The invention provides a synthesis method of astaxanthin, and belongs to the technical field of pharmaceutical chemicals, a compound 21 and a compound 22 are firstly prepared, then the compound 21 and the compound 22 are used for synthesizing a compound 5, and then the compound 5 and a compound 6 are used for generating astaxanthin, raw materials are easy to obtain in the whole preparation process, the synthesis process is safe and easy to operate, and the product yield is high; the compound 21 is 4-halogenated-2-methyl-2-butene-1-methylal, the compound 22 is 2, 2, 4, 6, 6-pentamethyl-5, 6, 7, 7a-tetrahydro-5-methylene-1, 3-benzodioxolane, the compound 5 is 3-methyl-5-(2, 6, 6-trimethyl-3-oxo-4-hydroxy-1-cyclohexenyl)-2, 4-pentadienyl triphenyl phosphine halide, and the compound 6 is 2,7-dimethyl-2, 4, 6-octyl trienaraldehyde.

Method for preparing astaxanthin by oxidizing canthaxanthin

The invention discloses a method for preparing astaxanthin by oxidizing canthaxanthin. The method comprises the following steps: dissolving a substrate canthaxanthin in an organic solvent; performingreacting by using a high-valence iodide as an oxidant to prepare a dialkoxy ketal compound; and hydrolyzing the ketal compound under acidic conditions to obtain astaxanthin. Therefore, problems of complex route and harsh conditions in the prior art are solved, and a safer and more practical method is provided for astaxanthin synthesis.

METHOD FOR PRODUCING OPTICALLY ACTIVE ASTAXANTHIN

PROBLEM TO BE SOLVED: To provide a method for producing an optically active 3(S),3'(S)-astaxanthin (I), with a 3(RS)-acetoxy-4-oxo-β-ionone derivative (IIab) of a racemate as the starting material. SOLUTION: The present invention provides a method for producing an optically active 3(S),3'(S)-astaxanthin, represented by formula (I), with a 3(RS)-acetoxy-4-oxo-β-ionone derivative (IIab) of a racemate as the starting material, the method including 8-9 separation and reaction steps. SELECTED DRAWING: None COPYRIGHT: (C)2018,JPO&INPIT

Fast regeneration of carotenoids from radical cations by isoflavonoid dianions: Importance of the carotenoid keto group for electron transfer

Electron transfer to radical cations of β-carotene, zeaxanthin, canthaxanthin, and astaxanthin from each of the three acid/base forms of the diphenolic isoflavonoid daidzein and its C-glycoside puerarin, as studied by laser flash photolysis in homogeneous methanol/chloroform (1/9) solution, was found to depend on carotenoid structures and more significantly on the deprotonation degree of the isoflavonoids. None of the carotenoid radical cations reacted with the neutral forms of the isoflavonoids while the monoanionic and dianionic forms of the isoflavonoids regenerated the oxidized carotenoid. Electron transfer to the β-carotene radical cation from the puerarin dianion followed second order kinetics with the rate constant at 25 °C k2 = 5.5 × 109 M-1 s-1, zeaxanthin 8.5 × 109 M-1 s-1, canthaxanthin 6.5 × 1010 M-1 s-1, and astaxanthin 11.1 × 1010 M-1 s-1 approaching the diffusion limit and establishing a linear free energy relationship between rate constants and driving force. Comparable results found for the daidzein dianion indicate that the steric hindrance from the glucoside is not important suggesting the more reducing but less acidic 4′-OH/4′-O- as electron donors. On the basis of the rate constants obtained from kinetic analyses, the keto group of carotenoids is concluded to facilitate electron transfer. The driving force was estimated from oxidation potentials, as determined by cyclic-voltametry for puerarin and daidzein in aqueous solutions at varying pH conditions, which led to the standard reduction potentials E° = 1.13 and 1.10 V versus NHE corresponding to the uncharged puerarin and daidzein. For pH > pka2, the apparent potentials of both puerarin and daidzein became constants and were E° = 0.69 and 0.65 V, respectively. Electron transfer from isoflavonoids to the carotenoid radical cation, as formed during oxidative stress, is faster for astaxanthin than for the other carotenoids, which may relate to astaxanthins more effective antioxidative properties and in agreement with the highest electron accepting index of astaxanthin.

METHODS FOR SYNTHESIS OF CHIRAL INTERMEDIATES OF CAROTENOIDS, CAROTENOID ANALOGS, AND CAROTENOID DERIVATIVES

A method used for synthesizing intermediates for use in the synthesis of carotenoids and carotenoid analogs, and/or carotenoid derivatives. In some embodiments, the invention includes methods for synthesizing optically active intermediates useful for the synthesis of optically active carotenoids.

METHOD FOR PRODUCING CAROTENOIDS

The invention relates to a method for producing carotenoids. Said method is characterised in that a dialkoxy dialdehyde of general formula I, where R1 = C1-C6 alkyl, is reacted with a phosphonium salt of formula II in a double Wittig condensation, or with a phosphonate of formula III in a double Wittig-Horner condensation, whereby the substituents in formulas II and III independently of one another are defined as follows: R2 = IV; R3 represents aryl; R4 to R6 represent C1-C6 alkyl and X- represents an anion equivalent of an inorganic or organic acid.

Carotenoid Sulfates. 4. Syntheses and Properties of Carotenoid Sulfates

Carotenoid sulfates have been prepared from 14 selected carotenols for spectroscopic characterization, studies of their stability in solution and their water solubility.Carotenoids containing sec non-allylic hydroxy groups provided sulfates stable in methanol solution, exemplified by zeaxanthin mono- and disulfate, alloxathin mono- and disulfate, fucoxanthin monosulfate, peridinin monosufate, capsorubin mono- and disulfate and astaxanthin mono- and disulfate.Acid catalyzed methanolysis of zeaxanthin disulfate gave zeaxanthin with complete retention of configuration.Enzymatic hydrolysis of alloxanthin monosulfate is reported.Less stable sulfates were obtained from sec vic diol type-, phenolic and tert-carotenols; caloxanthin, nostoxanthin, 3-hydroxyisorenieratene, 3,3'-dihydroxyisorenieratene, rhodovibrin, di-OH-lycopene and OH-chlorobactene.Acid catalyzed methanolysis of the tert caratenols proceeded via carbocations, judged by the solvolysis products characterized.Characteristic spectroscopic properties of carotenoid sulfates are pointed out.Water solubilities were studied.

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6-Oxo-isophoron. II. Ein neues Konzept fuer die Synthese von (3RS,3'RS)-Astaxanthin

Starting from 6-oxo-isophorone (2) a new concept for a seven-step synthesis of (3RS,3'RS)-astaxanthin (1) has been developed.As a key feature of the new approach, the oxidation state of astaxanthin (1) is adjusted already at an early stage of the synthesis.Thus, manipulation on more complex intermediates later in the synthesis is reduced to a minimum.Acetonide 10 or dimer 13 represent the key intermediates of this concept (Scheme 2).The whole sequence has been run on a kg scale with an overall yield of 52percent (s.Scheme 5).

Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus Oxo-isophoron. I. Modifizierung der Kienzle-Mayer-Synthese von (3S,3'S)-Astaxanthin

An efficient synthesis of (3S,3'S)-astaxanthin (1a) in high yield and optical purity starting from (4R,6R)-4-hydroxy-2,2,6-trimethylcyclohexanone (4) is reported.The absolute configuration of 1a, previously derived from ORD. data, has been confirmed by X-ray analysis of 5, a derivate of 6-oxo-isophorone (2).The key features of the improved synthesis are the two-step conversion of 4 to the key intermediate (4S)-2,6,6-trimethyl-4-hydroxy-2-cyclohexen-1-one (14), a new method for the partial reduction of the sterically hindered triple bond of (S)-6-hydroxy-3-(5-hydroxy-3-methyl-3-penten-1-ynyl)-2,4,4-trimethyl-2-cyclohexen-1-one (32), and Wittig olefination of the dialdehyde 1,6-dimethyl-1,3,5-octatrienedial (38) using phosphonium salt 37 with a free hydroxyl group.