Electron-withdrawing group Cope rearrangements

The absence of products derived from the oxonia-Cope rearrangement in the Panek study [64] can be explained by the presence of the C02Me group, which would destabilize the oxonia-Cope product 137 (R = C02Me) because the electron-withdrawing group is directly attached to the oxonium ion carbon. 

Cope rearrangement (10, 31). Acyclic 1,5-dienes substituted at C, by an electron-withdrawing group undergo Pd(II)-catalyzed Cope rearrangement at 40°. 

The Cope rearrangement of 1,2-divinylcyclobutanone 20 with terminal electron-withdrawing groups has also been effected by fluoride ion catalysis917. 

Pd(0)-catalyzed Cope rearrangement proceeds through a bis(7r-allyl)palladium(II) intermediate to afford the [1,3] and [3,3] rearranged products. The electron-withdrawing groups are required at the allylic position of 1,5-dienes to stabihze the bis(7r-allyl)palla-dium(II) intermediate, which is generated by the oxidative insertion of Pd(0) into the C—C cr-bond. 

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