Palladium colloid stabilized by block copolymer micelles as an efficient catalyst for reactions of C-C and C-heteroatom bond formation

Palladium nanoparticles stabilized in micelles formed by polystyrene-co-poly(ethylene oxide) and cetylpyridinium chloride as a surfactant were investigated as a catalyst in the following reactions: the Heck reaction of 2-ethylhexyl acrylate with iodobenzene and p-bromoacetophenone and heterocyclization of N-methylsulfonyl-o-iodoaniline with phenylacetylene and of methyl o-iodobenzoate with diphenylacetylene leading to formation of substituted indole and isocournarin, respectively. The activity of the colloidal palladium catalytic system is comparable to that of the low-molecular-weight palladium complexes, whereas the stability of the colloidal palladium system is much higher. The reuse of the catalyst was demonstrated in the experiments with fresh starts as well as by thermornorphous separation of the catalyst from products.