The palladium-catalyzedcyclopropanation of strainedalkenes with 3-pinacolatoboryl-1-arylallyl carboxylates was explored. The reactions proceeded smoothly under mild conditions, and the cyclopropanation products were obtained in good to high yields with high diastereoselectivities if CsF, 18-crown-6, and molecular sieves were used as additives. The reaction was hypothesized to proceed through the