Isolation by HPLC. and Identification by NMR. Spectroscopy of 11 mono-, di- and tri-cis isomers of an aromatic analogue of retinoic acid, ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-nona-2,4,6, 8-tetraenoate
✍ Scribed by Gerhard Englert; Siegfried Weber; Michael Klaus
- Publisher
- John Wiley and Sons
- Year
- 1978
- Tongue
- German
- Weight
- 685 KB
- Volume
- 61
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
Photoisomerization of an aromatic analogue of retinoic acid, ethyl all‐trans‐9‐(4‐methoxy‐2,3,6‐trimethylphenyl)‐3,7‐dimethyl‐nona‐2,4,6, 8‐tetraenoate 1 in dilute solutions of hexane, benzene, and ethanol yielded multi‐component mixtures of cis isomers which were separated by HPLC. FT‐^1^H‐NMR. at 270 MHz and, in some cases, homonuclear decoupling and Overhauser experiments as well as ^13^C‐NMR. were applied to establish the structures of 4 mono‐cis, 4 (of 6 possible) di‐cis, and 3 (of 4 possible) tri‐cis isomers. The structures of 3 isomeric esters, namely (2__Z__, 4__E__, 6__E__, 8__E__) 6, (2__Z__, 4__Z__, 6__E__, 8__E__) 9, and (2__Z__, 4__Z__, 6__Z__, 8__E__) 7 were independently confirmed by direct syntheses. The ^1^H‐NMR. data of all these compounds and the ^13^C‐NMR. data of the all‐trans and of 6 cis isomers available in sufficiently large quantities are discussed.