Synthesis and calcium channel antagonist activity of novel 1,4-dihydropyridine derivatives possessing 4-pyrone moieties

Screening Techniques for Drug Discovery in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive and irreversible impairment of memory and other cognitive functions of the aging brain. Pathways such as amyloid beta neurotoxicity, tau pathogenesis and neuroinflammatory have been used to understand AD, despite not knowing the definite molecular mechanism which causes this progressive disease. This review attempts to summarize the small molecules that target these pathways using various techniques involving high-throughput screening, molecular modeling, custom bioassays, and spectroscopic detection tools. Novel and evolving screening methods developed to advance drug discovery initiatives in AD research are also highlighted.

"One-Pot" Synthesis of γ-Pyrones from Aromatic Ketones/Heteroarenes and Carboxylic Acids

Despite the various attractive properties of γ-pyrones, there are still some deficiencies in their synthetic approaches such as lower atom economy, multistep processes, and prefunctionalization of the reagents. In this work, an efficient and simple (CF₃CO)₂O/CF₃SO₃H-mediated "one-pot" approach was realized to produce γ-pyrones by applying aromatic ketones/heteroarenes and carboxylic acids as the starting materials. The target products were isolated in moderate to excellent yields. The reaction mechanism was studied by density functional theory calculational methods. The results of experimental and theoretical investigations not only helped us explain the reason of high selectivity formation of β-diketones but also proved that 1,3,5-ketones might be important intermediates for the cyclization to afford γ-pyrones.

Ferrocene-Containing Ionic Liquid Supported on Silica Nanospheres (SiO2@Imid-Cl@Fc) as a Mild and Efficient Heterogeneous Catalyst for the Synthesis of Pyrano[3,2-b]Pyran Derivatives Under Ultrasound Irradiation

A novel heterogeneous silica nanosphere-supported ferrocene-containing ionic liquid catalyst (SiO2@Imid-Cl@Fc) was designed and synthesised and was systematically characterised by Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis. The catalytic activity of the SiO2@Imid-Cl@Fc catalyst was tested in a one-pot, three-component reaction of malononitrile and kojic acid with 15 aromatic aldehydes at room temperature under ultrasound irradiation. The products were pyrano[3,2-b]pyran derivatives, four of which are new. The catalyst exhibited good catalytic performance over short reaction times (15–20 min) and could be recycled at least five times without significant loss of activity.

Efficient synthesis of new pyrano[3,2-b]pyran derivatives via Fe3O4@SiO2-IL-Fc catalyzed three-component reaction

Ferrocene-containing ionic liquid supported on silica-coated Fe

Synthesis, spectroscopic and DFT studies of novel fluorescent dyes: 3-aminoimidazo[1,2-a]pyridines possessing 4-pyrone moieties

A series of novel imidazo[1,2-a]pyridines possessing 4-pyrone ring were synthesized by three-component condensation of 4-pyrone carbaldehydes, 2-aminopyridines and isocyanides. Bismuth (III) chloride was used as a catalyst in these reactions and desired products were synthesized in good yields at a very short period of time under solvent free conditions. UV-Vis absorption and fluorescence emission spectra of these compounds were investigated. It shown that two of these compounds (10f and 10g) exhibit intense fluorescence in dichloromethane. Optimized ground-state molecular geometries and orbital distributions of these two fluorescent dyes were obtained using density functional theory (DFT). Thermogravimetric analysis and electrochemical properties of these compounds were also studied.