A cobalt porphyrin efficiently catalyzed the formal [3+2] cycloaddition of alkyl-/aryl-substituted cyclopropanes and carbonylcompounds such as aldehydes and ketones to afford the corresponding substituted tetrahydrofurans. The use of the cobalt porphyrin complex as a Lewis acid to catalyze the reaction via the electrophilic activation of cyclopropanes was demonstrated. The high functional-group tolerance