Nickel-Catalyzed [3+1+1] Cycloaddition Reactions of Alkenyl Fischer Carbene Complexes with Methylenecyclopropanes

Methylenecyclopentanones were synthesized by the nickel-catalyzed [3+1+1] cycloaddition reactions of alkenyl Fischer carbene complexes with methylenecyclopropanes. The methylenecyclopropane was transformed into the C 2-symmetric bis-cyclopentapyridazine derivative by reacting with p-toluenesulfonyl hydrazine.