Palladium-Catalyzed Carboxylation of Activated Vinylcyclopropanes with CO2

By using a palladium catalyst with ZnEt2, activated viriylcyclopropanes were successfully converted into the corresponding beta,gamma-unsaturated carboxylic acid's in high yields under a CO2 atmosphere (1 atm). The intermediate in this reaction is thought to be a nucleophilic eta-allylethylpalladium species, which would be produced from pi-allylpalladium and ZnEt2 (umpolung reactivity).