New Approach to 4‐ and 5‐Aminopyrazole Derivatives

Abstract

3‐Oxo‐3‐(pyrrol‐2‐yl)‐propanenitrile 1 coupled with aromatic diazonium salts to yield the corresponding 2‐arylhydrazones 2a–c. The latter products reacted with chloroacetonitrile and ethyl chloroacetate to yield 4‐aminopyrazole derivatives 5a–f. Reaction of 2 with hydrazine hydrate led to formation of 5‐amino‐4‐arylazopyrazole 6a–c. Compound 1 reacted also with trichloroacetonitrile to yield enamine 7, which in turn reacted with hydrazine hydrate to yield 5‐amino‐3‐(pyrrol‐2‐yl)‐pyrazole‐4‐carbonitrile 8.

Keywords:

• 4‐amino and 5‐aminopyrazoles
• dimethylformamide dimethylacetale
• enamine
• 3‐oxo‐3‐(pyrrol‐2‐yl)‐propanenitrile