Under conventional, grinding and microwave methods, reaction of 3-methyl-1H-pyrazol-5-one 1 with benzene diazonium
chloride, 4-carboxybenzenediazonium chloride and nitrous acid furnished the diazenyl derivatives 2, 3 and 5, respectively.
Reaction of compound 3 with salicyladehyde and compound 5 with malononitrile followed by hydrazine hydrate afforded
compounds 4, 6 and 7, respectively. Compound 1 was converted to 4-bromopyrazolone 8, which when allowed to react with
urea, thiourea, o-phenylenediamine, 2-amino-3-hydroxypyridine and 2-amino-5-methylpheno furnished 4-aminopyrazolone 9-
13, respectively. While its reaction with p-phenylenediamine in 1:2 ratio gave bis-pyrazole derivative 14. Also, the reaction of
compound 1 toward thiosemicarbazide, thiourea, urea and guanidine hydrochloride gave the pyrazole derivatives 15, 16, 20
and 21, respectively. The reaction of compound 16 with benzaldehyde gave Schiff base 17, while its reaction with ethyl
chloroacetate gave the thioxoimidazolidinone derivative 18, which on reaction with thiosemicarbazide afforded
imidazotriazolothione derivative 19. Also, the reactivity of pyrazole 21 reacted with salicyladehyde and o-chloro benzaldehyde
was investigated to afford the corresponding Schiff base 22 and 23, respectively. These entire novel scaffolds have been proofed
using Elemental analysis, spectral data including IR, 1H-NMR in addition to 13C-NMR, and mass spectra. These new scaffolds
were screened for in vitro antimicrobial and cytotoxic activities. Most analogs revealed excellent to good results.