The reaction of 2, 2-dialkoxycyclopropane-1-carboxylates 1a-d and monoalkoxycyclopropane 1e with NOCl gives isoxazoline-and/or isoxazole-3-carboxylates by regioselective ring-opening at C1-C2 bond. A mechanistic interpretation suggests the intermediacy of well-stabilised dipolar species.
