Carotenoids

George Britton, Synnl/Jve Liaaen-Jensen and Hanspeter Pfander This book, Volume 2 in the series Carotenoids, is the first book to be published that is devoted entirely to the total synthesis of carotenoids, but it is timely in view of the rapid development and the growing diversification of the carotenoid field. The 1971 Carotenoids book contained a major chapter of 250 pages on total synthesis by H. Mayer and O. Isler. That comprehensive and authoritative review described systematically the construction of many synthons and the synthesis of many natural and unnatural carotenoids and related compounds. Twenty five years on, that chapter remains an essential reference work and source of information, with its extensive collection of tabulated data and lists of references to the original literature. Surveys of progress since 1971 have been presented at the IUPAC International Symposia on Carotenoids and are included in the published proceedings of these symposia. The history of major publications in the carotenoid field, leading to the development of this series, was outlined in the preface to the series published in Vol. IA. The general philo­ sophy outlined in that preface, with emphasis on practical guidance and the inclusion of worked examples of some of the most useful procedures, is maintained in Vol. 2. In kceping with this philosophy, Vol. 2 is not intended to be an exhaustive review of the literature, but is planned as a practical book, as well as a source of information.

Contenu

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 fr…