All of the chemical materials needed for the synthesis of pyrazolo [5, 4-d] benzopyrans, specially ethyl aceto acetate, butyril aceto acetate, phenyl hydrazine
, 2-hydroxy benzaldehyde and 4, 2- dihydroxy benzaldehyde were prepared by the German company, Merck.
Treatment of compound 1 with hydrazine hydrate or phenyl hydrazine
in absolute ethanol afforded indazole derivatives 2a-b in a one-pot reaction.
When compound 10 was interacted with one mole of hydrazine hydrate in the presence of acetic acid as a catalyst or one mole of phenyl hydrazine
in the presence of piperidine as a catalyst gave 1-(3,5-diamino-4-phenyl-3H-thieno[2,3-c]pyrazole-2(5H)-yl)ethanone 11 and 3,5-dihydro-2,4-diphenyl-2H-thieno[2,3-c]pyrazole-3,5-diamine 12 respectively.
In view of these important considerations, we report here synthesis of pyrazolylquinazolin-4(3H)-one, involves the base-catalyzed condensation of acetamido quinazolin-4(3H)-one with aromatic aldehydes to chalcones , which on subsequently undergoes cyclization reaction with phenyl hydrazine
 led to the formation of the desired compounds.
In the present study, some organic compounds of the type "aldehyde, ketone-amine condensation products," namely benzophenone-aniline; benzophenone; and p-hydroxy benzophenone derivative with phenyl hydrazine
; benzaldehyde and its p-methoxy derivatives with phenyl hydrazine
, were synthesized and investigated in NR mixes as accelerators.