Synthesis and antibacterial evaluation of novel heterocycles from 5-chloro-3-methyl-1-phenylpyrazole-4-carbaldehyde

910-9175-Chloro-3-methyl-1-phenylpyrazole-4-carbaldehyde 1 reacts with acetylpyrone 2 and acetylbenzopyrone 3 via Claisen-Schmidt condensation to afford heterochalcones 4a,b which undergo facile cyclisation with hydrazines to give 3,5-heteroaryl-2-pyrazolines 5a-d in quantitative yield. Further, heterochalcones 4a,b undergo addition reaction using Br2/MeOH in the presence of Pb(NO3)2 or AgNO3 to afford addition products 6a,b. The structures of the newly synthesized compounds have been established on the basis of their spectral studies. The newly synthesized heterochalcones and pyrazolines have been screened for their antibacterial activity against two kinds of strains using the Agar well diffusion method. Some of the compounds showed significant activity against both the strains

Thermal solvent-free synthesis of novel pyrazolyl chalcones and pyrazolines as potential antimicrobial agents

A novel approach was adopted for the synthesis of series of new pyrazolyl chalcones (3a-c) by the reaction of 5-chloro-3-methyl-1-phenylpyrazole-4-carboxaldehyde (1) with different 5-acetylbarbituric acid derivatives (2a-c) under thermal solvent-free condition. The chalcones were then converted to the corresponding pyrazolines (4a-c) under the same condition in excellent yields. All the synthesized compounds were characterized using elemental analysis and spectral data (IR, (1)H NMR, and mass spectrometry). The synthesized compounds were tested for their antimicrobial activity by disk diffusion assay with slight modifications against Gram-positive, Gram-negative strains of bacteria as well as fungal strains. The investigation of antimicrobial screening revealed that compounds (3a-4c) showed good antibacterial and antifungal activities, respectively. Among the screened compounds, 3b showed more potent inhibitory activity (MIC=12.5 μg/ml) nearly to that of standard antibiotics ciprofloxacin, griseofulvin and fluconazole

ChemInform Abstract: Thermal Solvent-Free Synthesis of Novel Pyrazolyl Chalcones and Pyrazolines as Potential Antimicrobial Agents.

Simple thermal heating under neat conditions gives access to new chalcones (III) which are then converted to the corresponding pyrazolines (IV) in a solvent‐free reaction