Synthesis of ketols of the natural pyrethrins
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society C: Organic
- No. 6,p. 1016-1024
- https://doi.org/10.1039/j39690001016
Abstract
A stereospecific five-stage synthesis of (±)-cis-pyrethrolone is described, involving cis-octa-1,3-dien-7-one as the key intermediate. The ethylene acetal of this ketone was made by a Wittig reaction, under salt-free condiditions, with vaporised acraldehyde. The overall yield for the synthesis was 21%, and it provides highly pure (pm;)-cis-pyrethrolone for the first time. The material is spectrally identical with a sample of naturel (+)-pyrethrolone. Improved syntheses of both (±)-cis-cinerolone and (±)-cis-jasmololone are reported. The cis-side chains are introduced by Wittig reactions or by selective hydrogenation of acetylenic intermediates. An allenic formulation, entertained for natural pyrethrolone in the early literature, is synthesised.Keywords
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