Lewis base promoted reactions of alkyne-dicobalt hexacarbonyls

The reactivity of alkyne-dicobalt hexacarbonyls changes dramatically depending on the nature of the coordinated Lewis base. Phosphines and phosphites stabilize alkyne-dicobalt hexacarbonyls when they coordinate. In contrast, sulfides and amines make the complexes reactive. The difference in σ-basicity and π-acidity on the central atom dramatically changes the reaction course of the resulting complexes. The coordination of primary amines promotes the stoichiometric Pauson-Khand reaction, the reduction of carbon-chlorine and carbon-oxygen bonds, hydrocarbamoylation and decomplexation. While ethers and alcohols also activate alkyne-dicobalt hexacarbonyls, the degree of activation appears less than amines. Ethers and alcohols are effective for the catalytic Pauson-Khand reaction.