A short, versatile, and diastereoselective method of preparing 2,7-nonadiene-5-carboxylic acids by an iterative enolate Claisen rearrangement procedure has been developed. Homochiral (E)- and (Z) secondary allylic alcohols 1-4, prepared from (S)-(-)-ethyl lactate, were esterified with acetic acid and enolized, and the resulting silyl ketene acetals were warmed to room temperature to effect [3,3]-sigmatropic rearrangement to 4-hexenoic acids 5-8. Esterification of these acids with alcohols 1-4 followed by a second enolate Claisen rearrangement delivered the targeted 2,7-nonadiene-5-carboxylic acids with high diastereoselectivity. This second [3,3]-sigmatropic rearrangement provides well-placed and potentially synthetically useful functionality and stereochemistry.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Organic Chemistry|
|State||Published - 1993|
ASJC Scopus subject areas
- Organic Chemistry