Two distinct nickel-catalyzed fully intermolecular three-component couplings are described. The catalytic addition of enals, alkynes, and alcohols provides γ,δ-unsaturated esters, whereas the catalytic addition of enones, alkynes, and aldehydes provides stereodefined, unsymmetrical 2-allyl-1,3-diketones. An internal redox process allows the reactions to proceed in the absence of reducing agents. On the basis of deuterium-labeling studies, a likely mechanistic pathway is proposed.
