An efficient synthesis of 1,3-diaryl-4-halo-1H-pyrazoles was achieved. The synthesis involves the [3 + 2] dipolar cycloaddition of 3-arylsydnones and 2-aryl-1,1-dihalo-1-alkenes. The process proceeds smoothly in moderate to excellent yields. 1,3-Diaryl-4-halo-1H-pyrazoles are found to be important intermediates that can easily be converted into 1,2,5-triaryl-substituted pyrazoles via Pd-catalyzed C-H bond activation.
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[Show abstract][Hide abstract]ABSTRACT: Pyrazoles are an important class of five membered heterocyclic compounds; are widely found as the core structure in a large variety of compounds that possess important agrochemical and pharmaceutical activities. Pyrazoles have been the recent target of numerous methodologies, mostly due to their prevalence as scaffolds in synthesis of bioactive compounds and reactions in different media. The aim of this review is to provide an up to date developments in the synthetic strategies, biological activities associated with pyrazole derivatives. Different synthetic methodologies and the diverse pharmacological activities of pyrazole moiety was discussed.
Full-text · Article · Oct 2013 · International Journal of PharmTech Research
[Show abstract][Hide abstract]ABSTRACT: Pyrazoles with an aldehyde function at C‐4 underwent a palladium‐catalyzed direct arylation reaction to provide a regioselective approach to 5‐aryl‐substituted pyrazoles. The reaction proceeds in moderate to high yields with a variety of aryl bromides in the presence of 2 mol‐% of Pd(OAc)2 as the catalyst. The use of an aldehyde function at C‐4 of the pyrazoles presents several advantages: (1) 4‐formylpyrazoles are easily prepared from hydrazine derivatives, ketones, and N,N‐dimethylformamide (DMF), (2) the control of the regioselectivity of the arylation at C‐5 of the pyrazole, (3) the aldehyde substituent can easily be transformed into a wide variety of other substituents, and (4) the formyl group can be considered a temporary protecting group, as it can be removed by a straightforward reaction. Pyrazoles with an aldehyde function at C‐4 underwent a palladium‐catalyzed direct arylation reaction to provide a regioselective approach to 5‐aryl‐substituted pyrazoles. The formyl substituent can be easily removed by using a Pd catalyst and, therefore, is considered a temporary protecting group.
No preview · Article · Mar 2014 · European Journal of Organic Chemistry
[Show abstract][Hide abstract]ABSTRACT: 1-Phenyl-3-(4-nitrophenyl)-5-(2-thienyl)-2-pyrazoline was synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction. UV-Vis spectra and fluorescence spectra were measured. Density functional theory calculations on the structure of the title compound were performed at the B3LYP/6-311G** level of theory. NPA atomic charge distributions indicate that, although the S atom in the thienyl ring loses coordination capacity, the title compound still may be used as a potential multi-dentate ligand to coordinate with metallic ions. The calculation of the second order optical nonlinearity was carried out. Natural bond orbital analyses indicate that the electronic absorption bands are mainly derived from the contribution of n → π* and π → π* transitions. Fluorescence spectra determination shows that the title compound is a potential orange-light emitting material.