Abstract
The reactivity of 3-position of pyrazolo-diazines to deacetylation or decarboxylation with conc. HCI and various electrophilic reagents was studied. The reactivety of these decreased in the order of pyrazolo-pyridazine and pyrazolo-pyrazine. By decarboxylation with conc. HCI or 40% H2SO4, 3-acetyl-2, 5-dimethylpyrazolo [1, 5-c] pyrimidine (XI) or methyl 5-substituted phenylpyrazolo [1, 5-c] pyrimizine-3-carboxylate (XII) were easily converted into 3, 4, 6-trimethyl-1H-pyrazolo [1, 5-c] pyridine (XXIV) or 5-substituted phenacylpyrazole-4-carboxylic acid (XXV), involving ring fission and recyclization.
