The synthesis of regioisomeric spiroisoxazolines was achieved through an intramolecular cyclization/methylation reaction of a functionalized 5,5-disubstituted isoxazoline in one reaction vessel. The 5,5-isoxazoline was constructed through a 1,3-dipolar cycloaddition reaction of an aromatic nitrile oxide and a geminal disubstituted alkene.
spiro compounds - regioselectivity - cycloadditions - ring closure - heterocycles