PAMAM dendrimer-palladium complex catalyzed synthesis of five-, six- or seven membered ring lactones and lactams by cyclocarbonylation methodology

Palladium complexes immobilized onto generations 0-3 PAMAM dendrimers supported on silica, in the presence of 1,4-bis(diphenylphosphino)butane, were used as catalysts for the cyclocarbonylation of 2-allylphenols, 2-allylaniline, 2-vinylphenol and 2-vinylaniline affording five-, six- or seven membered ring lactones and lactams. Good conversions were realized using the catalytic system, and the catalyst was recycled 3-5 times. The influence of the spacer chain was investigated, as well as the solvent and the CO/H2 ratio, on the selectivity and the recyclability of the cyclocarbonylation reactions.