The synthesis of fused and pendant pyrazole heterocyclic compounds from 5‐amino‐3‐methyl‐1‐phenylpyrazole and their evaluation as fluorescent brightening agents

5‐Amino‐3‐methyl‐1‐phenylpyrazole ( 1 ) has been condensed with EMME ( 2 a) and EMCA ( 2 b) and the resulting ethyl 5‐aminoacrylates ( 3 a–b) cyclized to pyrazolo[3,4,‐b]pyridines ( 4 a–b). 3‐Methyl‐1‐phenylpyrazol‐5‐yl diazonium salt ( 7 ), prepared from ( 1 ) was coupled with tobias acid ( 8 ) and 2‐methoxy‐6‐aminoquinoxaline ( 9 ) to get the corresponding O‐aminoarylazo and heterylazo dyes ( 10 ) which were oxidatively cyclized to 2‐N‐(3‐methyl‐1‐N‐phenylpyrazol‐5‐yl)‐1,2,3‐triazolo[4,5‐a] naphthalene and [4,5‐f] quinoxaline derivative ( 11 ). The spectral properties of the compounds ( 4 a–b, 5 , 6 , 11 a–b) were studied.