Pyrazolidine-3,5-diones with heterocyclic substituents. II. Acylation of 5-Hydrazino-3-phenyl-1H-1,2,4-triazoles

Abstract

Basic condensation of 5-hydrazino-1-methyl-3-phenyl-1H-1,2,4-triazole with diethyl malonates gives β-hydrazides of malonic acids, their decarboxylated products and dihydrazides as the main products in low yields; diethyl monophenylmalonate and diethylmalonate also afford the expected pyrazolidinediones in poor yield. The corresponding β-benzoyl derivative resists pyrazolidinedione formation. N1-Benzoyl derivatives of hydrazinotriazoles transacylated to the more basic hydrazine nitrogen. The 4-phenylamino derivative of 6,6-diethyl-2-phenyl-s- triazolo[1,5-a]pyrimidine-5,7(4H,6H)-dione rearranges to the corresponding pyrazolidinedione but the analogous 4- benzoyl-amino compound is demalonylated under the same conditions. Catalytic hydrogenation of the 4-(2?-propylideneimino) analogue fails and attempted reduction by sodium borohydride cleaves the pyrimidine ring.