[5+1] Cocyclization of (Cyclopropylmethylene)cyclopropanes and other Vinylcyclopropanes with Carbon Monoxide Catalyzed by Octacarbonyldicobalt

Vinylcyclopropanes react with octacarbonyldicobalt stoichiometrically under mild conditions to give cyclohex-3-enones in moderate to good yields (51-75%). Catalytic amounts of the cobaltcarbonyl complex or a rhodiumcarbonyl complex also mediate [5+1] cocyclizations of vinylcyclopropanes with carbon monoxide (under CO balloon pressure) to give cyclohex-3enones in good yields (up to 95%).