Synthesis and spectroscopic characterization of the doubly locked 9E,11Z retinal model systems 7E,13E-11,19–10,20-dimethanoretinal and its 13Z isomer
✍ Scribed by M. Groesbeek; G. W. Robijn; J. Lugtenburg
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 756 KB
- Volume
- 111
- Category
- Article
- ISSN
- 0165-0513
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✦ Synopsis
Abstract
7E,13E‐11,19‐10,20‐dimethanoretinal (1) and its 13__Z__ isomer 2 were prepared from β‐ionone, using the novel synthon 2‐(diethoxyphosphinyl)‐5,5‐dimethoxyhexanenitrile. This synthon was also used to prepare 7E,9E,13E‐10,20‐methanoretinal (3) and its 13__Z__ isomer 4 in high yield, starting from β‐ionone. Spectroscopic analysis (mass, ^1^H and ^13^C NMR and UV/Vis) of these compounds is discussed. The introduction of the methano bridges leads to minimal steric and electronic changes. The photostationary state reached from 1 and 2 has the 13__Z__ form 2 as the main constituent. This is one of the very few with a Z form as the main constituent of the photostationary state. 1 and 2 are very sensitive to acid‐catalyzed isomerization of the 13‐C14‐C double bond. The presence of the 11,19‐methano bridge is responsible for this efficient Z‐E isomerization.