Thermally induced reactions of 5-aminoisoxazoles and 2H-azirine-2-carboxamides were studied. The isoxazoles produce pyrazine-2,5-dicarboxamides or 2H-azirine-2-carboxamides, depending on the conditions. The azirines similarly yield pyrazine-2,5-dicarboxamides. The photochemistry of 5-aminoisoxazoles and 2H-azirine-2-carboxamides is also reported.