REACTIONS WITH CYCLIC AMIDENES-III - SYNTHESIS OF SOME NEW FUSED PYRAZOLE DERIVATIVES

Diazotised 5-amino-3-hydroxy-4-phenylazopyrazole (1 a) and 3,5-diamino-4-phenylazo- pyrazole (1 b) coupled with active methylene reagents to yield the pyrazolo[1,5-c]-as-triazine derivatives (3a, b-5a, b). On the other hand coupling of diazotised 1 a, with β-naphthal has afforded the acyclic azo derivative (6). Whereas diazotised 1 a underwent intramolecular cyclisation into the pyrazolo[1, 5-c]- 1, 2, 3, 4-tetrazine derivative (3) on attemptet addition to acrylonitrile, diazotised 1 b reacted with acrylonitrile under the same conditions to yield the pyrazolo[1, 5-c]-pyridazine derivative (4). Compounds 1 a, b reacted with benzoylisothiocyanate to yield the pyrazol-5-ylthiourea derivatives (10 a, b). Whereas 10 a readily cyclised into the pyrazolo[3, 4-c]-as-triazine derivative (11) on refluxing with pyridine, compound 10 b hydrolysed under the same conditions into the pyrazol-5-ylthiourea derivative (12). © 1979, Walter de Gruyter. All rights reserved.