Abstract
Reaction of 2-methyl-3-ethoxy-3-methoxypropionitrile (I), 2-methoxymethylenepropionitrile (II), or 2-ethoxymethylenepropionitrile (III) and methylhydrazine in ethanol containing conc. hydrochloric acid gives 5-amino-1, 4-dimethylpyrazole (V) and 3-amino-1, 4-dimethylpyrazole (VI) in approximately equal quantities. Further reaction of VI with I, II, or III gives 1, 3, 6-trimethylpyrazolo[1, 5-a]pyrimidin-7(1H)-one (VIII).
Similarly, reaction with hydrazine hydrate gives 4-methyl-5-aminopyrazole (X) which is led to 3, 6-dimethyl-7-aminopyrazolo[1, 5-a]pyrimidine (XI). Hydrolysis of XI followed by methylation gives VIII. On the other hand, methylation of XI gives 3, 4, 6-trimethyl-7-imino-4, 7-dihydropyrazolo[1, 5-a]pyrimidine (XIII), whose hydrolysis affords the 7-one compound (XIV). Reaction of VIII with hydrazine hydrate results in its cleavage into 4-methyl-4-pyrazolin-3-one (IX) and 1, 4-dimethyl-3-aminopyrazole (VI), while XIV undergoes similar cleavage into IX and 4-methyl-5-methylaminopyrazole (XV). These reactions confirm the structure of these compounds. It should be noted that XI has a fairly strong antifebrile and analgesic activity.
