Struktur und Eigenschaften von 5‐epi‐Flavoxanthin und 5‐epi‐Chrysanthemaxanthin

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Abstract
Structure and properties of 5‐epi‐flavoxanthin and 5‐epi‐chrysanthemaxanthinThe absolute configurations of 5‐epi‐flavoxanthin (6) and 5‐epi‐chrysanthemaxanthin (7) prepared by acid catalysed rearrangement of semi‐synthetic lutein epoxide 5 are shown to be (3S, 5S, 8R, 3′R, 6′R) and (3S, 5S, 8S, 3′R, 6′R), respectively. Contrary to published data [5] the relationship of the polyene chain and H3(18) on the dihydrofurane ring is cis for the pair of stereoisomers having a Δδ = δ (HC(7)) − δ (HC(8)) = 0,22 ppm and 3J ≡ 0. These conclusions are in full accord with the chiroptical data.