Intramolecular carbonylation reactions with recyclable palladium-complexed dendrimers on silica: Synthesis of oxygen, nitrogen, or sulfur-containing medium ring fused heterocycles

Palladium-complexed dendrimers supported on silica were evaluated as catalysts for intramolecular carbonylation reactions. The results showed that dendritic catalysts display high activity, affording oxygen, nitrogen, or sulfur-containing seven- or eight-membered ring fused heterocycles in excellent yields. Moreover, these catalysts have competitive advantages in that they can be easily recovered by simple filtration in air and reused for up to eight cycles with only a slight loss of activity.