Nickel substituted polyoxometalates in layered double hydroxides as metal-based nanomaterial of POM-LDH for green catalysis effects

Three nickel substituted Keggin-type polyoxometalates, α-[SiW₉O₃₇{Ni(H₂O)}₃]^-10 (denoted as SiW₉Ni₃), was intercalated into Zn₃Al based Layered Double Hydroxide (Zn₃Al-LDH) by the selective ion-exchange technique. The as-synthesized nanocomposite, SiW₉Ni₃@Zn₃Al, was used as heterogeneous nanoreactor to promote the synthesis of drug-like aminoimidazopyridine small molecule skeletons via the well-known Ugi-type Groebke-Blackburn-Bienaymé reaction (GBB 3-CRs) in the absence of any acid/additive and under mild and solvent-free conditions. A synergistic catalytic effect between SiW₉Ni₃ polyoxometalate and Zn₃Al-LDH precursors is evidenced by a higher catalytic property of the SiW₉Ni₃@Zn₃Al composite compared to the individual constituents separately. Lewis/Bronsted acidity of the SiW₉Ni₃ polyoxometalate and Zn₃Al-LDH precursors appear to be essential for the catalytic performance of the composite. Furthermore, the catalytic performance of SiW₉Ni₃@Zn₃Al was also tested in GBB 3-CRs synthesis of amino imidazothiazole under mild and solvent-free conditions.

Synthesized NaA nanozeolite as a catalyst for the preparation of 3-amino imidazo[1,2-a]pyridines under solvent-free conditions

Abstract:

The present study explores a new method for the fabrication of NaA nanozeolite as a simple and efficient catalyst for the production of 3-aminoimidazo [1,2-a] pyridines through the 3-component reaction of aldehydes, 2-aminoperidines and isocyanides under solvent-free conditions. The production of organic template free (OTF) NaA nanozeolite was performed at room temperature. The prepared nanozeolite was identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electronic microscopy (FESEM), N2 sorption isotherm and particle size analysis (PSA). The particle sizes of synthesized spherical NaA nanozeolite were under 100 nm via the FESEM method. The BET surface area, total pore volume and mean pore diameter of the created sample were attained to be 362 m2g-1, 0.44 cm3 g-1 and 5.9 nm, respectively. The developed method has some advantages such as OTF production of NaA nanozeolite, simple synthesis method with short reaction time and easy separation using filtration and the ability to recycle and reuse of catalyst several times without reducing its efficiency.

Design, synthesis and anticancer activity of 2-arylimidazo[1,2-a]pyridinyl-3-amines

A series of imido-heterocycle compounds were designed, synthesized, characterized, and evaluated for the anticancer potential using breast (MCF-7 and MDA-MB-231), pancreatic (PANC-1), and colon (HCT-116 and HT-29) cancer cell lines and normal cells, while normal cells showed no toxicity. Among the screened compounds, 4h exhibited the best anticancer potential with IC₅₀ values ranging from 1 to 5.5 μM. Compound 4h caused G2/M phase arrest and apoptosis in all the cell lines except MDA-MB-231 mammosphere formation was inhibited. In-vitro enzyme assay showed selective topoisomerase IIα inhibition by compound 4h, leading to DNA damage as observed by fluorescent staining. Cell signalling studies showed decreased expression of cell cycle promoting related proteins while apoptotic proteins were upregulated. Interestingly MDA-MB-231 cells showed only cytostatic effects upon treatment with compound 4h due to defective p53 status. Toxicity study using overexpression of dominant-negative mutant p53 in MCF-7 cells (which have wild type functional p53) showed that anticancer potential of compound 4h is positively correlated with p53 expression.

Sulfonated β-cyclodextrins: efficient supramolecular organocatalysts for diverse organic transformations

The present review summarizes various organic transformations carried out by using sulfonated β-cyclodextrins such as β-cyclodextrin sulfonic acid, β-cyclodextrin propyl sulfonic acid, and β-cyclodextrin butyl sulfonic acid as an efficient, supramolecular reusable catalyst under diverse reaction conditions.

Nanocrystalline ZnO: A Competent and Reusable Catalyst for the Preparation of Pharmacology Relevant Heterocycles in the Aqueous Medium

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Nanoparticle catalyzed synthesis is a green and convenient method to achieve most of the chemical transformations in water or other green solvents. Nanoparticle ensures an easy isolation process of catalyst as well as products from the reaction mixture avoiding the hectic work up procedure. Zinc oxide is a biocompatible, environmentally benign and economically viable nanocatalyst with effectivity comparable to the other metal nanocatalyst employed in several reaction strategies. This review mainly focuses on the recent applications of zinc oxide in the synthesis of biologically important heterocyclic molecules under sustainable reaction conditions.

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Application of zinc oxide in organic synthesis: Considering the achievable advantages of this nanocatalyst, presently several research groups are paying attention in anchoring zincoxide or its modified structure in several types of organic conversions e.g. multicomponent reactions, ligand-free coupling reactions, cycloaddition reaction, etc. The advantages and limitations of this nanocatalyst are also demonstrated. The present study aims to highlight the recent multifaceted applications of ZnO towards the synthesis of diverse heterocyclic motifs. Being a promising biocompatible nanoparticle, this catalyst has an important contribution in the fields of synthetic chemistry and medicinal chemistry.

The Groebke-Blackburn-Bienaymé Reaction

Imidazo[1,2-a]pyridine is a well-known scaffold in many marketed drugs, such as Zolpidem, Minodronic acid, Miroprofen and DS-1 and it also serves as a broadly applied pharmacophore in drug discovery. The scaffold revoked a wave of interest when Groebke, Blackburn and Bienaymé reported independently a new three component reaction resulting in compounds with the imidazo[1,2-a]-heterocycles as a core structure. During the course of two decades the Groebke Blackburn Bienaymé (GBB-3CR) reaction has emerged as a very important multicomponent reaction (MCR), resulting in over a hundred patents and a great number of publications in various fields of interest. Now two compounds derived from GBB-3CR chemistry received FDA approval. To celebrate the first 20 years of GBB-chemistry, we present an overview of the chemistry of the GBB-3CR, including an analysis of each of the three starting material classes, solvents and catalysts. Additionally, a list of patents and their applications and a more in-depth summary of the biological targets that were addressed, including structural biology analysis, is given.

A facile I2-catalyzed synthesis of imidazo[1,2-a]pyridines via sp3 C–H functionalization of azaarenes and evaluation of anticancer activity

A three component synthetic protocol has been developed for the synthesis of medicinally important imidazo[1,2-a]pyridines via the iodine-catalyzed oxidative amination of benzylic C–H bonds of azaarenes. The synthesized compounds were evaluated for their anti-cancer activity.

Sulfonic acid functionalized silica-coated CuFe2O4 core–shell nanoparticles: an efficient and magnetically separable heterogeneous catalyst for the synthesis of 2-pyrazole-3-amino-imidazo-fused polyheterocycles

Synthesis of easily separable magnetic core–shell nanoparticles and their efficient use as catalyst in a multicomponent reaction.