Two easy photochemical methods for the conversion of commercial ionone alpha into regioisomerically enriched γ-ionone and γ-dihydroionone
✍ Scribed by Stefano Serra; Claudio Fuganti; Elisabetta Brenna
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 158 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0882-5734
- DOI
- 10.1002/ffj.1832
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✦ Synopsis
Abstract
Commercial ionone alpha was converted into regioisomerically enriched __γ‐__ionone and __γ‐__dihydroionone by mean of two synthetic routes, each involving a photochemical reaction as a key step. Using visible light, oxygen and methylene blue as photosensitizer, ionone alpha was transformed in 4‐hydroxy‐__γ‐__ionone isomers, which were deoxygenated to afford __γ‐__ionone by mean of triethylammonium formate in the presence of (Ph~3~P)~2~PdCl~2~ as catalyst. Irradiation of dihydro‐__α‐__ionol acetate, using high‐pressure mercury lamps and xylene as photosensitizer afforded __γ‐__dihydroionol acetate, which, after purification by crystallization of the corresponding p‐nitrobenzoyl ester, was converted to pure __γ‐__dihydroionone. Copyright © 2007 John Wiley & Sons, Ltd.