Linkage of the PAMAM type dendrimer with the gel type resin based on glycidyl methacrylate terpolymer as a method of preparation of the polymer support for the recyclable palladium catalyst for Suzuki–Miyaura cross-coupling reactions†
Poly(amidoamine) PAMAM type hyperbranched systems were immobilized on an epoxy functionalized polymer based on glycidyl methacrylate (the GMA resin). Two methods were applied. The first included two-stage synthesis of the zeroth order PAMAM dendrimer (1), starting from tris(2-aminoethyl)amine (TAEA), and its immobilization on the GMA resin. The second relied on multi-stage chemical modification of the GMA resin in turn with TAEA, methyl acrylate and ethylenediamine. The provided multi NH2-functionalyzed polymers (abbreviated respectively 2 and 5) were used for immobilization of palladium(II) ions to obtain two polymer supported palladium catalysts (2-Pd and 5-Pd, respectively). The synthesized polymers and polymer supported Pd catalysts were characterized using different instrumental techniques (FT-IR, DR UV-Vis, ICP-OES, DSC and SEM). Catalyst 2-Pd was found as a clearly more active in the model reaction of p-bromoanisole. It was tested successfully as catalysts in the Suzuki–Miyaura cross-coupling reactions of a series of aryl bromides with phenylboronic acid in water–organic solvent systems. It was also recycled successfully ten times in the coupling reaction of p-bromoanisole with phenylboronic acid carried out in the mixture of isopropyl alcohol and water (1 : 1 v/v) at 70 °C.