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Synthese und Chiralität von (5R, 6R)-5,6-Dihydro-β, ψ-carotin-5,6-diol, (5R, 6R, 6′R)-5,6-Dihydro-β, ε-carotin-5,6-diol, (5S, 6R)-5,6-Epoxy-5,6-dihydro-β, ψ-carotin und (5S, 6R, 6′R)-5,6-Epoxy-5,6-dihydro-β,ε-carotin

✍ Scribed by Walter Eschenmoser; Peter Uebelhart; Conrad Hans Eugster

Publisher
John Wiley and Sons
Year
1979
Tongue
German
Weight
331 KB
Volume
62
Category
Article
ISSN
0018-019X

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✦ Synopsis

Synthesis and Chirality of (5__R__, 6__R__)‐5,6‐Dihydro‐β, ψ‐carotene‐5,6‐diol, (5__R__, 6__R__, 6′R)‐5,6‐Dihydro‐β, ε‐carotene‐5,6‐diol, (5__S__, 6__R__)‐5,6‐Epoxy‐5,6‐dihydro‐β,ψ‐carotene and (5__S__, 6__R__, 6′R)‐5,6‐Epoxy‐5,6‐dihydro‐β,ε‐carotene

Wittig‐condensation of optically active azafrinal (1) with the phosphoranes 3 and 6 derived from all‐(E)‐ψ‐ionol (2) and (+)‐(R)‐α‐ionol (5) leads to the crystalline and optically active carotenoid diols 4 and 7, respectively. The latter behave much more like carotene hydrocarbons despite the presence of two hydroxylfunctions. Conversion to the optically active epoxides 8 and 9, respectively, is smoothly achieved by reaction with the sulfurane reagent of Martin [3]. These syntheses establish the absolute configurations of the title compounds since that of azafrin is known [2].

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