Reaction of hydrazidic halides with cyanoacetic acid derivatives

Ethyl cyanoacetate reacts with the hydrazidic halides IV-VI in presence of sodium ethoxide in ethanol at room temperature to give the pyrazole derivatives VIII-X respectively. Similar treatment of IV-VIII with cyanoacetanilide gives the substituted pyrazoles XI-XIV respectively. The results show that IV to VIII, unlike I, follow one and the same sequence in their reactions with cyanoacetic acid derivatives. The structure assignments of the products VIII-XIV were based on elemental analysis and spectral evidence.