Catalytic Activity of Pd(AcO)2 Coordinated to Crosslinked Polymeric Isocyanides

Palladium acetate (Pd(AcO)2) undergoes easy and quantitative coordination to hydrophilic macromolecular isocyanides to give monoisocyano-Pd(AcO)2 species, ℘-NC-Pd. These macromolecular complexes are the precursors of the active, versatile and reusable catalyst for the hydrogenation of 1-hexene, 1,5-cyclooctadiene, phenylacetylene, benzaldehyde, trans-2-hexenal and nitrobenzene under mild conditions. Direct (ESCA) and indirect (IR) evidence suggest that PdII undergoes reduction to Pd0. ℘-NC-Pd catalysts are also active, but not reusable, for the double bond migration reaction in terminal olefins. ℘-NC-Pd are very poor catalysts for the telomerization of butadiene with 2-methoxycarbonylcyclohexanone, carbon dioxide, enamines and acetaldehyde. Severe metal leaching is observed and the apparent catalytic activity is most likely a homogeneous phase phenomenon.