Activation of C-O and C-N Bonds in Allylic Alcohols and Amines by Palladium Complexes Promoted by CO₂. Synthetic Applications to Allylation of Nucleophiles, Carbonylation, and Allylamine Disproportionation

The direct activation of the C-O bonds in allylic alcohols catalyzed by palladium complexes has been accelerated by carrying out the reactions under CO₂. On reaction with diethylamine, allyl alcohol can be converted into N,N-diethylallylamine in the presence of palladium complexes at room temperature under normal pressure of carbon dioxide. Allylation of various carbon nucleophiles such as β-keto esters and β-diketones can be achieved by using allylic alcohols directly in the presence of palladium complexes and CO₂. Direct carbonylation of allylic alcohols into unsaturated carboxylic acids can be catalyzed by palladium complexes under the pressure of CO and CO₂. Disproportionation of diallylamine into triallylamine and allylamine is also catalyzed by palladium complexes in the presence of CO₂. On the basis of studies on the behavior of η³-allylpalladium hydrogencarbonate complexes with the nucleophiles, mechanisms are proposed to account for the palladium-catalyzed allylation processes influenced by CO₂.