Cyclic hydroxamic acids: synthesis of 4-hydroxy-1H-1,2,4-triazolin-5-ones

Cyclic Hydroxamic Acids: Synthesis of 4-Hydroxy-1H-1,2,4-triazolin-5-ones A series of 4-hydroxy-1H-1,2,4-triazolin-5-ones ( 3 ) was prepared by cyclization of 2-acylhydrazine-1-carboxylic esters ( 4 ) with hydroxylamine or by reaction of arylhydroxamoyl chlorides with methyl hydrazinecarboxylate and cyclization of the hydrazidoxime intermediate 11 with base. None of the new compounds showed significant antibacterial or antimycotic activity.