Catalytic Pauson-Khand Reaction Using PEG-Stabilized Cobalt Nanoparticles

Significance

The PEG-stabilized cobalt nanoparticles which were prepared by thermal decomposition of [Co₂(CO)₈] in PEG₁₀₀₀ or PEG₅₀₀₀ were shown to be highly active and selective catalysts, for intra- and intermolecular Pauson-Khand reactions. Thus, the intramolecular Pauson-Khand reaction of enynes 1 with 3.3 mol% of Co nanoparticles and CO (30 bar) in THF gave the corresponding cyclopentenones 2 (eq. 1). The intermolecular Pauson-Khand reaction of norbornene 3 with different alkynes 4 occurred also smoothly under similar conditions to give the corresponding compounds 5 (eq. 3).