Five- or seven-membered ring lactones are synthesized, in good selectivity and high yields, by the cyclocarbonylation reaction of 2-allylphenols, using a tridentate diphosphinoaryl ligand (PCP-type) palladium(II) catalyst immobilized on silica (A) and silica supported dendrimers (B, C and D). These immobilized catalysts, which are highly active and can be recycled by simple filtration in air, and reused with only moderate loss of activity, combine the advantages of heterogeneous and homogeneous catalysts. These complexes are also stable towards oxygen and moisture.