Conventional, Grinding and Microwave-Assisted Synthesis, Biological Evaluation of some Novel Pyrazole and Pyrazolone derivatives

Abstract

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.