Studies on enaminonitriles: A new synthesis of 1,3-substituted pyrazole-4-carbonitrile

Abstract

3-Diethylaminoacrylonitrile (1) reacts with hydrazonyl halides (2a-d) to yield 1,3-disubstituted pyrazole-4-carbonitriles 5a-d. The acetyl 1-p-chlorophenylpyrazole-4-carbonitrile (5a) condensed with hydrazine hydrate to yield the bishydrazone 10 and with dimethylformamide dimethylacetal to yield 1-aryl-3-(3-dimethylamino)acryloyl pyrazole-4-carbonitrile (11). This enamine reacts with hydrazine hydrate to yield the pyrazolylpyrazole (12) and with naphthoquinone to yield the 3-naphthofuranoyl pyrazole 13. The pyra-zolyl pyridine derivative 14 was obtained upon treatment of 11 with acetylacetone in the presence of ammonium acetate. Compound 11 was coupled with p-chlorobenzene diazonium chloride to yield the hydrazone 16 that was coupled further with p-chlorobenzenediazonium chloride to yield the formazane 18.