Reactions with 3,5-pyrazolidinediones. III. Cyanoethylation of Some 4-Arylazo Derivates of 3,5-Pyrazolidinediones and 3-amino-2-pyrazolin-5-ones

4-Arylazo-3,5-pyrazolidinediones 1 react with acrylonitrile to yield either 4-arylazo-1-β-cyanoethyl-3,5-pyrazolidinediones 2 or 4-arylazo-1,2-di-β-cyanoethyl-3,5-pyrazolidinediones 3 depending on the reaction conditions. Hydrolysis of 2 and 3 affords the corresponding acids 4 and 5 . Treatment of 4-arylhydrazono-3-amino-2-pyrazolin-5-ones 6 with acrylonitrile affords either the mono-β-cyanoethyl derivatives 7 or the pyrazolopyrimidine derivatives 10 depending on the reaction conditions.