Development of chelate resin-supported palladium catalysts for chemoselective hydrogenation

Two kinds of palladium catalysts immobilized on a chelate resin bearing diiminoacetate or polyamine moieties on the polystyrene-divinylbenzene polymer were newly prepared by the adsorption of palladium (II) ions on these resins followed by the reduction to palladium (0) with hydrazine monohydrate. Both catalysts showed a similar activity for hydrogenation. A variety of reducible functionalities, except for benzylic alcohol, alkyl benzyl ether, silyl ether, and epoxide, could be reduced under the hydrogenation conditions using either catalyst. Since the palladium metal elution from the immobilized catalysts was never observed, the catalysts could be reused without any decrease in the catalyst activity for at least 5 runs.

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