¹H‐NMR.‐, ¹³C‐NMR.‐, UV.‐ und CD.‐Daten von synthetischem (3<i>S</i>, 3′<i>S</i>)‐Astaxanthin, seinem 15‐<i>cis</i>‐Isomeren und einigen analogen Verbindungen

Abstract

1 H‐NMR., 13 C‐NMR., UV. and CD. spectral data of synthetic (3 S , 3′ S )‐astaxanthin, its 15‐ cis isomer, and some related compounds 1 H‐NMR., 13 C‐NMR., UV. and CD. spectra are reported for synthetic (3 S , 3′ S )‐astaxanthin ( 1 ), its 15‐ cis isomer ( 2 ), its diacetate ( 3 ), and the 15, 15′‐didehydro compound ( 5 ). These data prove the identity of the synthetic and the naturally occuring compound 1 . A full interpretation of the 1 H‐ and 13 C‐NMR. spectra is given and confirms the configuration of all the double bonds. The conformation of the cyclohexene end group of all the compounds is shown to be identical. The signs of the different CD. maxima of 15‐ cis ‐astaxanthin are found to be opposite to those of the all‐ trans compound.