[3+2] Cycloaddition Reaction of Cyclopropyl Ketones with Alkynes Catalyzed by Nickel/Dimethylaluminum Chloride

Nick and Al join forces: The nickel-catalyzed [3+2] cycloaddition between the title compounds gives cyclopentene derivatives in the presence of Me2AlCl. The organoaluminum reagent activates the carbonyl group of the cyclopropyl ketone through coordination of the oxygen atom to the aluminum, and stabilizes the reaction intermediate by the coordination of the chloride to nickel. cod=1,5-cyclooctadiene, THF=tetrahydrofuran.