Silicotungstic acid catalysed Claisen Schmidt condensation reaction: an efficient protocol for synthesis of 1,3-diaryl-2-propenones

Design and introduction of quaternary ammonium hydroxide-functionalized graphene oxide quantum dots as a pseudo-homogeneous catalyst for epoxidation of α,β-unsaturated ketones

In present work, design and synthesis of a novel pseudo-homogeneous catalyst is described. For this purpose, amine-functionalized graphene oxide quantum dots (N-GOQDs) were prepared from graphene oxide (GO) by a facile one-step oxidative fragmentation approach. The prepared N-GOQDs were then modified with quaternary ammonium hydroxide groups. Various characterization techniques clearly revealed that the quaternary ammonium hydroxide-functionalized GOQDs (N-GOQDs/OH^-) have been successfully synthesized. TEM image revealed that the GOQDs particles are almost regularly spherical in shape and mono-dispersed with particle sizes < 10 nm. The efficiency of the synthesized N-GOQDs/OH^- as a pseudo-homogeneous catalyst in epoxidation of α,β-unsaturated ketones in the presence of aqueous H₂O₂ as an oxidant at room temperature was investigated. The corresponding epoxide products were obtained in good to high yields. This procedure has the advantages of a green oxidant, high yields, involvement of non-toxic reagents and reusability of the catalyst without discernible loss in activity.

Hf(OTf)4-Catalyzed Three-Component Synthesis of N-Carbamate-Protected β-Amino Ketones

Hafnium(IV) triflate (Hf(OTf)₄) has been identified as a potent catalyst for the direct three-component synthesis of β-carbamate ketones. This new method, featuring a low catalyst loading, fast reaction rate, and solvent-free conditions, provided facile access to a diversity of carbamate-protected Mannich bases. A mechanistic investigation indicated that the three-component reaction proceeds via sequential aldol condensation and aza-Michael addition, but not the Mannich-type pathway.

(E,E)-3-Methyl-2,5-bis-(4-methyl-benzyl-idene)cyclo-penta-none: synthesis, characterization, Hirshfeld surface analysis and anti-bacterial activity

The title compound, (E,E)-3-methyl-2,5-bis-(4-methyl-benzyl-idene)cyclo-penta-none (MBMCP), C22H22O, was obtained by Claisen-Schmidt condensation of 4-methyl-benzaldehyde with 3-methyl-cyclo-penta-none in good yield. The structure of MBMCP was studied using UV, FT-IR and Raman spectroscopy, single-crystal X-ray diffraction (XRD) measurements, and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The mol-ecular structure of MBMCP is fully extended in the E,E configuration. C-H⋯π stacking inter-actions play a significant role in the stabilization of the mol-ecular packing. Hirshfeld surface analysis was used to qu-antify the non-covalent inter-actions in the crystal lattice. Microbiological studies were performed to investigate the anti-microbial activity of this new product.

Halo-Substituted Chalcones and Azachalcones-Inhibited, Lipopolysaccharited-Stimulated, Pro-Inflammatory Responses through the TLR4-Mediated Pathway

A series of B-ring, halo-substituted chalcones and azachalcones were synthesized to evaluate and compare their anti-inflammatory activity. Mouse BALB/c macrophage RAW 264.7 were pre-treated with 10 μg/mL of each compound for one hour before induction of inflammation by lipopolysaccharide (1 μg/mL) for 6 h. Some halo-chalcones and -azachalcones suppressed expression of pro-inflammatory factors toll-like receptor 4 (TLR4), IκB-α, transcription factor p65, interleukine 1β (IL-1β), IL-6, tumor necrosis factor α (TNF-α), and cyclooxygenase 2 (COX-2). The present results showed that the synthetic halo-azachalcones exhibited more significant inhibition than halo-chalcones. Therefore, the nitrogen atom in this series of azachalcones must play a more crucial role than the corresponding C-2 hydroxyl group of chalcones in biological activity. Our findings will lay the background for the future development of anti-inflammatory nutraceuticals.

Solvent-free synthesis, spectral correlations and antimicrobial activities of some aryl E 2-propen-1-ones

Totally 38 aryl E 2-propen-1-ones including nine substituted styryl 4-iodophenyl ketones have been synthesised using solvent-free SiO2-H3PO4 catalyzed Aldol condensation between respective methyl ketones and substituted benzaldehydes under microwave irradiation. The yields of the ketones are more than 80%. The synthesised chalcones were characterized by their analytical, physical and spectroscopic data. The spectral frequencies of synthesised substituted styryl 4-iodophenyl ketones have been correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. The antimicrobial activities of 4-iodophenyl chalcones have been studied using Bauer-Kirby method.

Effects of structural and electronic characteristics of chalcones on the activation of peroxisome proliferator-activated receptor gamma

Chalcones share some structural similarities with GW-1929, a highly-selective and potent agonist for peroxisome proliferator-activated receptor-gamma (PPARγ). In this study, we tested 53 structurally diverse chalcones to identify characteristics essential for PPARγ activation in a GAL4-based transactivation assay. This screen identified several novel chalcone agonists of PPARγ. Our results indicate that chalcones with an electron rich group or sterically large groups such as naphthyl on the carbonyl side tend to activate PPARγ. The absence of any strict structural or electronic requirements suggests that the flexibility of the PPARγ ligand binding pocket may allow binding of diverse chalcones with some preference for a slightly larger electron-rich group on the carbonyl side. We predict that further structure-activity relationship studies on chalcones with naphthalene or electron-rich groups near the carbonyl moiety will lead to the development of more potent PPARγ agonists.