A Practical Chemo-enzymatic Approach to Highly Enantio-Enriched 10-Ethyl-7,8-dihydro-γ-ionone Isomers: A Method for the Synthesis of 4,5-Didehydro-α-Ionone
| Autor: | Zeid Abdullah Al-Othman, Yahia Nasser Mabkhot, Assem Barakat, Abdullah M. Al-Majid |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | International Journal of Molecular Sciences, Vol 13, Iss 5, Pp 5542-5553 (2012) |
| Druh dokumentu: | article |
| ISSN: | 13055542 1422-0067 |
| DOI: | 10.3390/ijms13055542 |
| Popis: | An efficient and convenient strategy for the enantioselective synthesis of enantiomerically enriched 10-ethyl-7,8-dihydro-γ-ionone isomers (R)-(+)-7, and (S)-(−)-7 are described utilizing a lipase mediated resolution protocol, and reductive elimination of the secondary allylic alcohol as the key step. The enantioselective and diastereoselective lipase kinetic acetylation of 4-hydroxy-γ-ionone derivatives 6a afforded the 4-acetyl-γ-ionone derivatives (−)-8, and the 4-hydrox-γ-ionone derivatives (+)-6a, which are suitable precursors of the desired products. Stereospecific palladium-mediated elimination of allylic acetate provides the target compounds with an excellent enantiomeric excess and yield. Additionally, the novel 4,5-didehydro-α-ionone 13 is obtained from readily prepared (2,6,6-trimethylcyclohexa-2,4-dien-1-yl) methanol 9. The structures of all newly synthesized compounds have been elucidated by 1H, 13C NMR, GC-MS, and IR spectrometry. These compounds represent a new class of odorants that may be of pivotal relevance in industrial perfumery. |
| Databáze: | Directory of Open Access Journals |
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