Wittig reaction of aldehyde (I) with methylene triphenylphosphorane produced olefin (II). Oxime (IV) was prepared from methyl 4-formylbenzoate (III) by treatment with hydroxylamine. The nitrile oxide generated from imine (IV) by chlorination, followed by elimination under basic conditions, underwent a [3+2] regioselective cycloaddition with alkene (II) to produce isoxazoline (V). Oxidation of the isoxazoline ring of (V) to the corresponding isoxazole derivative (VI) was accomplished by treatment with N-bromosuccinimide. Finally, ester hydrolysis with LiOH furnished the title carboxylic acid.