Efficient synthesis of spiroisoxazoline oxindoles

The synthesis of spiroisoxazoline oxindoles containing ester groups at position 4′ and aromatic or ester groups at position 3′ of the isoxazoline ring is reported. The compounds were synthesized in yields up to 94% by 1,3-dipolar cycloaddition of 3-methylene indolin-2-ones and chlorooximes in the presence of triethylamine or zinc.