Palladium Immobilized on Silica Gel: A Novel and Reusable Catalyst for Heck Reaction

The immobilization of palladium on silica gel in Heck reaction has been developed. Iodobenzenes, bromobenzenes and activated chlorobenzenes were coupled with olefins (Heck reaction) smoothly to afford the corresponding cross-coupling products in good to excellent yields under phosphine- and amine-free reaction conditions in the presence of silica gel supported palladium, Silica-Ap-Pd cat. as catalyst, potassium carbonate as base and DMF as solvent. Furthermore, the silica-supported palladium catalyst 3 could be recovered and recycled by a simple filtration of the reaction solution and used for 6 consecutive trials without significant loss of its catalytic activity.