Synthesis of large ring macrocycles (12-18) by recyclable palladium-complexed dendrimers on silica gel catalyzed intramolecular cyclocarbonylation reactions.

Intramolecular cyclocarbonylation reactions with palladium-complexed dendrimers on silica gel as catalysts are very effective for the synthesis of twelve- to eighteen-membered ring macrocycles. This process can tolerate a wide variety of functional groups, including halide, ether, ketone, and ester. The heterogeneous dendritic catalysts facilitate excellent substrate reactivity, affording oxygen-, nitrogen-, or sulfur-containing tricyclic heterocycles in 70-92 % yields. Importantly, these systems are easily recovered by simple filtration and reused several times with only a slight loss of activity.