Synthesis of pyrazolo[1,5- a]-pyrimidines by reaction of 3,5-diamino-4-nitropyrazole with acetoacetic ester in the presence of alkaline agents.

Two major compounds are formed in the reaction of 3,5-diamino-4-nitropyrazole with acetoacetic ester: 2-amino-5-methyl-3-nitro-4,7-dihydropyrazolo[1,5-a]pyrimidin-7-one and 3-amino-5-(β-hydroxycrotonyl)amino-4-nitropyrazole. The latter is converted to bicyclic dihydropyrazolo[1,5-a]-pyrimidinone in solutions with heating. [ABSTRACT FROM AUTHOR]