Catalytic Regioselective Control in the Diastereoselective 1,3‐Dipolar Cycloaddition Reactions of 1‐(1‐Alkynyl)cyclopropyl Ketones with Nitrones

The power of the catalyst: The cycloaddition pattern of 1-(1-alkynyl)cyclopropyl ketones 1 with nitrones 2 can be controlled by subtle alterations in the choice of catalyst. From the same two starting materials, two useful heterocyclic compounds can be selectively prepared.