Carotenoids

1: General Aspects.- I: Synthesis in Perspective.- II: Strategies for Building the Carbon Skeleton.- A. Introduction.- B. General Strategies.- C. Examples.- 1. Wittig reaction: Astaxanthin and zeaxanthin.- 2. Julia sulphone coupling: Zeaxanthin.- 3. Wittig reaction with unsymmetrical carotenoids: (S)-Trisanhydrobacterioruberin.- 4. Dimerization: ?,?-Carotene.- References.- III: Characterization of Products.- A. Introduction.- B. Isomers of ?,?-carotene.- C. (7Z)-Lycopene.- D. Lutein.- E. Zeaxanthin.- F. 3,4,3?,4?-Tetraacetoxypirardixanthin.- References.- 2: Coupling Reactions.- I: Enol Ether and Aldol Condensations.- A. Introduction.- B. Enol Ether Condensations.- 1. Alkyl enol ethers.- 2. Trimethylsilyl enol ethers.- C. Aldol Condensations.- References.- II: Organometallic Reactions.- A. Introduction.- B. General Procedures.- C. Metals of Groups IA, IIA and IIIB (Li, Na, Mg and Zn).- 1. Metal acetylides (alkynylides).- 2. Metal alkenyls.- 3. Allylic alkali metal derivatives.- 4. Zinc reagents.- D. Palladium-mediated and Nickel-mediated Reactions.- 1. Palladium.- 2. Nickel.- E. Copper.- 1. Cadiot-Chodkiewicz coupling reaction.- 2. Cuprates.- F. Low-valent Titanium.- References.- III: Wittig Olefination.- A. Introduction.- B. Phosphorus Ylides.- 1. Reactivity of phosphorus ylides.- 2. Production of phosphorus ylides.- C. Stereochemistry.- 1. Factors that influence stereoselectivity.- 2. Steric control.- D. Reaction Mechanisms.- E. Horner-Wadsworth-Emmons Olefination.- F. Use of the Wittig Reaction in Carotenoid Synthesis.- 1. Introduction.- 2. Bond formation between C(7)/C(8), or C(7?)/C(8?).- 3. Bond formation between C(11)/C(12), or C(11?)/C(12?).- 4. Bond formation between C(15)/C(15?).- References.- IV: Sulphone Coupling.- A. Alkylation - Elimination Method.- 1. Synthesis of vitamin A derivatives.- 2. Synthesis of carotenoids.- B. Double Elimination Method.- References.- 3: Carotenoid Synthesis.- I: Polyene Synthons.- A. Introduction.- B. Symmetrical Central C10-Components.- 1. C10-Components of various functionality.- 2. Industrial routes to the C10-dialdehyde.- 3. Unsymmetrically functionalized central C10-components.- C. Synthesis of Protected C15- and C20-Dialdehydes.- D. C10-Components for the Synthesis of Segments C(8) to C(15) and C(15?) to C(8?).- E. 1,4-Bifunctional Isoprenoid C5-Building Blocks.- 1. (E)-4-Acetyloxy-2-methylbut-2-enal.- 2. Monoacetals of (E)-2-methylbut-2-ene-1,4-dial.- 3. C5-Phosphonium ester salts and C5-phosphonate esters.- 4. 5-Hydroxy-4-methyl-2(5H)-furanone.- References.- II: Acyclic Carotenoids.- A. Introduction.- B. Carotenoids with the ? End Group.- C. Carotenoids with the 3,4-Didehydro-? End Group.- D. Carotenoids with the 1,2-Dihydro-? End Group.- E. Carotenoids with the l-Hydroxy-3,4-didehydro-l,2-dihydro-? End Group.- F. Carotenoids with the l-Methoxy-3,4-didehydro-l,2-dihydro-? End Group.- G. Carotenoids with the 1-Hydroxy-1,2-dihydro-? End Group.- H. Carotenoids with the 16-Hydroxy-? End Group.- I. Carotenoids with the l,2-Dihydroxy-3,4-didehydro-l,2-dihydro-? End Group.- J. Carotenoids with the 1,2-Epoxy-1,2-dihydro-? End Group.- K. Carotenoids with the 1-Methoxy-2-keto-3,4-didehydro-l,2-dihydro-? End Group.- L. C45- and C50-Carotenoids.- M. Diapocarotenoids.- References.- III: Synthesis of Cyclic Carotenoids.- A. Introduction.- B. Carotenoids with the ? End Group.- 1. ?,?-Carotene.- 2. Carotenoids with the 3,4-didehydro-? end group.- 3. Retro-carotenes.- 4. Carotenoids with the 2-hydroxy-? end group.- 5. Carotenoids with the 3-hydroxy-? end group.- 6. Carotenoids with the 4-hydroxy-? end group.- 7. Carotenoids with the 3,4-dihydroxy-? end group.- 8. Carotenoids with the 5,6-dihydroxy-5,6-dihydro-? end group.- 9. Carotenoids with the 3,5,6-trihydroxy-5,6-dihydro-? end group.- 10. Carotenoids with the 5,6-epoxy-5,6-dihydro-? end group.- 11. Carotenoids with the 5,8-epoxy-5,8-dihydro-? end group.- 12. Carotenoids with the 3-hydroxy-5,6-epoxy-5,6-dihydro-? end group.- 13. Carotenoids with the 2-oxo-3,4-didehydro-? end group.- 14. Carotenoids with the 3-oxo-retro-? end group.- 15. Carotenoids with the 4-oxo-? end group.- 16. Carotenoids with the 3-hydroxy-4-oxo-? end group.- C. Carotenoids with the ? End Group.- 1. ?,?-Carotene and ?,?-carotene.- 2. Carotenoids with the 3-hydroxy-? end group.- D. Carotenoids with the ? End Group.- E. Carotenoids with the ? End Group.- F. Carotenoids with Aromatic End Groups.- 1. Carotenoids with the ? end group.- 2. Carotenoids with the 3-hydroxy-? end group.- 3. Carotenoids with the ? end group.- G. C50-Carotenoids.- 1. Carotenoids with a substituted ? end group.- 2. Carotenoids with a substituted ? end group.- 3. Carotenoids with a substituted ? end group.- H. Norcarotenoids.- References.- IV: Synthesis of Acetylenic, Allenic and In-chain Substituted Carotenoids.- A. Introduction.- B. Synthesis of Acetylenic Carotenoids.- C. Synthesis of Allenic Carotenoids.- D. Synthesis of Butenolide Carotenoids.- 1. Sulphone method.- 2. Synthesis of the optically active C15-epoxyformyl ester.- 3. Synthesis of the optically active C22-allenic sulphone with an abnormal location of the in-chain methyl group.- 4. Synthesis of optically active peridinin.- E. Synthesis of ?-Diketone Carotenoids.- 1. The aldol condensation route.- 2. The Wittig condensation route.- 3. The Claisen condensation route.- References.- V: Total Synthesis of (Z)-Isomers.- A. Introduction.- B. Strategy.- C. Formation of (Z)-Double Bonds by Synthesis.- 1. Sterically unhindered disubstituted (Z)-double bond (15Z).- 2. Sterically hindered disubstituted (Z)-double bonds (7Z and 11Z).- 3. Trisubstituted (Z)-double bonds (5Z, 9Z and 13Z).- 4. Thermodynamicly favoured cis double bonds.- D. Direct synthesis of (Z)-isomers.- 1. Carotenes.- 2. Xanthophylls.- 3. Apocarotenoids.- References.- VI: Labelled Carotenoids.- Synthesis.- 1. Synthesis and use of 13C-labelled synthons.- 2. Synthesis of the central C10-unit with 13C-labels.- 3. Synthesis of unlabelled synthons.- 4. Synthesis of labelled carotenoids.- 5. Deuterium-labelled spheroidenes.- References.- VII: Technical Syntheses.- A. Economic Importance.- 1. Sales.- 2. Areas of application.- B. Industrial Carotenoid Syntheses not involving any Wittig Olefination.- 1. Carotenoid synthons from the Roche synthesis of vitamin A.- 2. ?,?-Carotene.- 3. Apo-?-carotenoids.- 4. Xanthophylls.- C. Industrial Carotenoid Syntheses by means of Wittig Olefination.- 1. Carotenoid building blocks from the BASF synthesis of vitamin A.- 2. ?,?-Carotene.- 3. Apo-?-carotenoids.- 4. Xanthophylls.- D. Formulation.- 1. Colouration of lipophilic media.- 2. Colouration of hydrophilic media - Production of bioavailable preparations.- References.- VIII: Partial Synthesis of Glycosides and Glycosyl Esters.- A. Carotenoid Glycosides.- B. Carotenoid Glycosyl Esters.- References.- IX: Partial Synthesis of Sulphates.- A. Introduction.- B. General Route.- C. Synthesis of Stable Carotenoid Sulphates.- D. Synthesis of Less Stable Carotenoid Sulphates.- E. Preparation and Solvolysis Reactions of Unstable Carotenoid Sulphates.- F. Properties of Carotenoid Sulphates.- References.- Worked Examples.- Example 1: Enol Ether Condensation.- A. Introduction.- B. Examples.- References.- Example 2: Organometallic Reactions.- A. Introduction.- B. Synthesis of Ethynyl-?-ionol.- C. Synthesis of Vinyl-?-ionol.- D. Synthesis of (Z)-?-Ionylideneacetic Acid.- References.- Example 3: Wittig and Horner-Emmons Reaction.- A. Introduction.- B. Syntheses of ?-Apo-8?-carotenoic acid ethyl esters.- References.- Example 4: Sulphone Coupling.- A. Retinoic Acid by the Alkylation-Desulphonylation Method.- B. (all-E)-Retinyl Acetate by the Double Elimination Method.- References.- Example 5: Asymmetric Syntheses.- Asymmetric Epoxidation.- Asymmetric Dihydroxylation.- References.- Example 6: Synthesis ex Chiral Pool.- A. Introduction.- B. Examples.- References.- Example 7: Optical Resolution of Racemic ?-Ionone.- A. Introduction.- B. Synthesis of (R)-(+)-?-Ionone.- Example 8: ?,?-Carotene.- A. Introduction.- B. Synthesis of ?,?-Carotene by use of the Wittig Reaction.- C. Synthesis of ?,?-Carotene by use of Low-valent Titanium.- Appendix I: List of Synthons.- Appendix II: List of Naturally Occurring Carotenoids Prepared by Total Synthesis.- List of abbreviations.