3-Hydroxyisoxazole-5-hydroxamic acid

The synthesis of the title compound, 3-hydroxyisoxazole-5-hydroxamic acid (4b), by two procedures is described. The first, involving the treatment of dimethyl acetylenedicarboxylate with hydroxylamine, had previously been reported to give the 3-hydroxyisoxazole-5-carboxylic acid (4a). In the second, treatment of chlorofumaroyl dichloride with hydroxylamine also gave the intermediate chlorofumarodihydroxamic acid (6). Compound 6 was found to have some activity against P388 lymphocytic leukemia.