Articles
STAUDINGER AND RUZICKA’S ALTERED PYRETHROLONE: THE CYCLOPENTADIENONE DIMERS DERIVED FROM PYRETHRIN I
Article number
1073_25
Pages
181 – 190
Language
English
Abstract
The reaction of pyrethrin I (1) with sodium hydroxide in ethanol produced the cyclopentadienone 29 which rapidly underwent Diels-Alder dimerisation to give two cyclopentadienone dimers which were isolated in 30 and 38% yield, respectively.
A combination of one-dimensional and two-dimensional NMR spectroscopic studies allowed determination of the structure and stereochemistry of the higher and lower Rf dimers as being 26 and 27, respectively.
The dimers are formed by cycloaddition reactions of the least substituted alkene of the cyclopentadienone, and via both possible regioisomeric endo transition states.
A combination of one-dimensional and two-dimensional NMR spectroscopic studies allowed determination of the structure and stereochemistry of the higher and lower Rf dimers as being 26 and 27, respectively.
The dimers are formed by cycloaddition reactions of the least substituted alkene of the cyclopentadienone, and via both possible regioisomeric endo transition states.
Authors
O.E. Hutt, J.A. Freemont, S. Littler, P.J. Duggan, J. Tsanaktsidis, H. Cole, M. Kerr, J.H. Ryan
Keywords
Tanacetum cinerariifolium, natural pyrethrins, pyrethrin I, pyrethrolone, cyclopentadienone, Diels-Alder dimerisation
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