Crystallographic, spectroscopic and thermal studies of 1-(4-bromophenyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)-3-methyl-1H-pyrazole

The new title pyrrole-pyrazole derivative, C16H16BrN3, was synthesized through a citric acid-catalyzed Paal-Knorr reaction between acetonylacetone and 1-(4-bromophenyl)-3-methyl-1H-pyrazol-5-amine under mild reaction conditions. This synthetic protocol is noteworthy for its utilization of stoichiometric amounts of the reactants, an ecofriendly solvent and a cost-effective, non-toxic and biodegradable organocatalyst. A comprehensive understanding of the molecular structure was gained through spectroscopic, thermal and X-ray crystallographic analyses. The crystal structure is characterized by weak interactions, where only C-H...π connections contribute to the hydrogen-bond contacts. The supramolecular assembly is controlled by dispersion forces. However, the energy frameworks demonstrate that these forces act in three dimensions, providing enough stability, as observed in TGA-DSC (thermogravimetric analysis-differential scanning calorimetry) studies.

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

An effective one-pot strategy was developed for the synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones from pyrazolo[3,4-b]pyridin-6-ones, obtained by reacting 5-aminopyrazoles with 4-arylidene-2-phenyloxazol-5(4H)-ones (azlactones) under solvent-free conditions, through subsequent elimination of a benzamide molecule in a superbasic medium (t-BuOK/DMSO). The fluorescent properties of the synthesized compounds were studied. 4-Arylpyrazolo[3,4-b]pyridin-6-ones luminesce in the region of 409-440 nm with a quantum yield of 0.09-0.23 when irradiated with UV light.

Synthesis of novel antioxidant and antitumor 5-aminopyrazole derivatives, 2D/3D QSAR, and molecular docking

5-Aminopyrazole serves as a vital precursor for several biologically active pyrazoloazines, including pyrazolopyridine, pyrazolopyrimidine, and pyrazolotriazine, as well as Schiff bases, thiourea, and phthalimide derivatives. In this study, we structurally characterized novel pyrazole derivatives by spectral IR, ¹H and ¹³C NMR, and MASS spectroscopy. We also evaluated antioxidant activity of various derivatives using ABTS and DPPH methods and cytotoxicity in the hepatocellular carcinoma Hep-G2 cells by SRB assay. The most potent antitumor molecules were 5-aminopyrazole derivative 3, chloroacetanilide derivative 8, maleimide derivative 10a, pyrazolopyrimidine 16, and enamine 19, with IC₅₀ values of 41, 3.6, 37, 24.4, and 17.7 μM, respectively. Complementary computational studies predicted QSAR and bioactivity of these molecules. Interestingly, the most effective compounds were also predicted to be kinase inhibitors; in addition, molecular docking with liver receptors (3MBG, 4XCU, and 4G9C) predicted promising interactions.