Desymmetrisation of meso-methylcyclooctanones. Highly enantioselective synthesis of C8 syn-isoprenoid and syn,syn-deoxypropionate subunits from a bicyclo[3.3.1]nonane precursor
✍ Scribed by Augusto Gambacorta; Daniela Tofani; Paolo Lupattelli; Andrea Tafi
- Book ID
- 104250653
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- French
- Weight
- 144 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
The methyl esters of 3R,7S-dimethyl-and 3R,5R,7S-trimethyl-8-hydroxyoctanoic acids have been prepared in good yields and with e.e. >98% by chemical elaboration of the known exo, exo-3,7-dimethylbicyclo[3.3.1]nonan-9-one, the key step involving the desymmetrisation of the intermediate meso-ketones cis-3,7-dimethyl-and cis,cis-3,5,7-trimethyl-cyclooctanone through the corresponding chiral enolates generated by the lithium amide of the (+)bis[(R)-(1-phenylethylamine)]. The very high enantioselectivity observed might be related to the conformational features of the eight-membered ring.