Cu-Catalyzed Hydrocarbonylative C-C Coupling of Terminal Alkynes with Alkyl Iodides.

A Cu-catalyzed hydrocarbonylative C-C coupling of terminal alkynes with unactivated alkyl iodides has been developed, enabling highly chemo- and regioselective synthesis of unsymmetrical dialkyl ketones. A variety of functional groups are tolerated, and both primary and secondary alkyl iodides react well. An autotandem sequence of two Cu-catalyzed processes is proposed: first hydrocarbonylative coupling of the alkyne and the alkyl iodide, followed by reduction of the intermediate unsaturated ketone to the saturated product. Mechanistic experiments indicate that an alkenylcopper intermediate activates the alkyl iodide by single electron transfer to enable a radical carbonylation pathway.