pyrethrine

sign up: Jenny Saravia, Miranda Maestrelli, Sam Morris

where do we start? I would suggest disconnecting from the cyclopropyl ring. You know that these are made with carbenes or carbenoids. The direct precurser of this must be a trans alkene. You also know how to make these from alkynes. The double bond at the end must be formed after the cyclopropyl ring, because otherwise the carbene or carbenoid would have reacted at both positions. You have several ways of doing this, including grignard followed by dehydration (not compatable with a carboxyl) or a wittig, which is compatable, at least with esters. One side of the double bond would be a secondary center, the other side a tertiary center. Which one would be best for forming the phosphine yilid? I hope this helps, Bruce Bondurant

After researching, I found that the synthesis of pyrethrin involves the esterification of (+)-trans-chrysanthemic acid with (S)-(Z)-pyrethrolone.The starting material for the synthesis uses epoxycarane. A lactone is eventually formed and the ring is opened by using a Grignard reagent to form (+)-trans-chrysanthemic acid. The final step is the addition of an activated zinc compound to reduce the triple carbon bond to form the cis product (S)-pyrethrolone. Does this sound right? I'm a little confused about the "containing 6 carbons or less" part...? [] --- Miranda Maestrelli



Here are my two attempts. I'm not completely sure about either one but any feedback is appreciated. Thanks! --- Miranda Maestrelli

pyrethroids are a family of insecticides, all originally derived from six chemicals called pyrethrins, found in the chrysanthemum. Pyrethrin I and Pyrethrin II are structurally related [|esters] with a [|cyclopropane] core. Would any of these work? http://en.wikipedia.org/wiki/Pyrethrin ~Jenny Saravia here is my attempt!

Sam Morris- Here are my four pages

[|pyrethrin_synthesis.jpg], [|pyrethrin_synthesis_2.jpg], [|pyrethrin_synthesis_3.jpg], [|pyrethrin_synthesis_4.jpg]