1,2,5-Selenadiazoles. Synthesis and properties

4-Amino-1, 2, 5-selenadiazole-3-carboxylic acid and 4-amino-1, 2, 5-selenadiazole-3-carboxamides have been prepared by ring-cleavage of 1, 2, 5]selenadiazolo3, 4-d]pyrimidin-7(6H)-one by basic reagents. The primary amide (III), as well as an N-alkyl amide, may be produced by the action of a primary amine. Hydrazine reductively cleaves the selenadiazole ring. The preparation of similar 4-ureido derivatives by ring-cleavage of 1,2,5]selenadiazolo3, 4-d]pyrimidine-5, 7(4 H, 6H)-dione has been demonstrated with two examples. N-Butyl-4-ureido-1, 2, 5-selenadiazole-3-carboxamide is easily hydrolyzed in aqueous base to the corresponding acid, and it has been shown that this reaction proceeds by way of 1, 2, 5]selenadiazolo3,4-d]pyrimidine-5, 7 (4H, 6H)-dione. The 4-amino-1, 2, 5-selenadiazole-3-carboxylic acid derivatives have marked cytotoxic, antibacterial, and antifungal activity.