Hydrotrope: green and rapid approach for the catalyst-free synthesis of pyrazole derivatives

Environmentally Benign Lewis Acid Promoted [2+3] Dipolar Cycloaddition Reactions of Nitrile Imines with Alkenes in Water

“…The data are presented as the frequency of absorption (cm -1 ), and only selected absorptions (ν max ) are reported. The NMR spectroscopic data ( 1 H NMR at 300 MHz, 13…”

“…[12] Furthermore, in some cases in which 1,3-dipoles were generated in situ, micellar catalysts were often used under basic reaction conditions. [13] A number of pharmaceutical drugs such as celecoxib [14,15] and rimonabant [16] feature a pyrazole moiety [17] as the core phamacophore, and structurally similar synthetic analogues such as pyrazolines and spiropyrazolines also have potential to be biologically active. Because a 1,3dipolar cycloaddition is commonly utilized for the syntheses of the aforementioned heterocycles, [18] we report herein the results from the investigation of a mild and environmentally friendly nitrile imine based 1,3-dipolar cycloaddition methodology.…”

Greener and Environmentally Benign Methodology for the Synthesis of Pyrazole Derivatives

“…Madhuri Barge et al [85] . develop greener and ecofriendly approach for synthesis of pyrazole (73) in presence of hydrotropic aqueous medium.…”

The Structure ofN‐phenyl‐pyrazoles and Indazoles: Mononitro, Dinitro, and Trinitro Derivatives

“…Both classical methods to prepare the pyrazoles of the present publication, reaction of nitroarylhydrazines with β‐dicarbonyl compounds and N ‐arylation of pyrazoles, have been the subject of many studies trying to improve the yields or to make them cleaner (green). For instance, in the case of compounds 3 and 36 (4‐nitrophenyl derivatives), the following procedures have been reported for the first method: potassium aluminum sulfate , Sc(OTf) 3 , Zn[(L)proline] 2 , Mg(HSO 4 ) 2 , P 2 O 5 ·SiO 2 , nano‐silica sulfuric acid , and tungstate sulfuric acid as catalysts; hydrotropic solution and glycerol‐water as solvent , under catalyst‐free conditions; and in aqueous medium using Saccharomyces cerevisae biocatalyst .…”