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Struktur und Eigenschaften von 5‐ epi ‐Flavoxanthin und 5‐ epi ‐Chrysanthemaxanthin
Author(s) -
Cadosch Herbert,
Vögeli Ulrich,
Rüedi Peter,
Eugster Conrad Hans
Publication year - 1978
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19780610502
Subject(s) - chemistry , polyene , stereochemistry , epoxide , cotton effect , absolute configuration , ring (chemistry) , circular dichroism , organic chemistry , catalysis
Structure and properties of 5‐ epi ‐flavoxanthin and 5‐ epi ‐chrysanthemaxanthin The 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 (3 S , 5 S , 8 R , 3′ R , 6′ R ) and (3 S , 5 S , 8 S , 3′ R , 6′ R ), respectively. Contrary to published data [5] the relationship of the polyene chain and H 3 (18) on the dihydrofurane ring is cis for the pair of stereoisomers having a Δδ = δ (HC(7)) − δ (HC(8)) = 0,22 ppm and 3 J ≡ 0. These conclusions are in full accord with the chiroptical data.