A number of isoxazoline, isoxazole and pyrazole carboxylic acids or their esters has been synthesized via the 1,3-dipolar cycloaddition of corresponding nitrile oxides or diazomethane to unsaturated dipolarophiles. The obtained substances are of the interest as the precursors of new 1,2-diacyl-1-alkylhydrazines which are perspective as highly selective insecticides
