Copper(II) Schiff-Base Complex Modified UiO-66-NH2(Zr) Metal-Organic Framework Catalysts for Knoevenagel Condensation-Michael Addition-Cyclization Reactions

The synthesis of five- and six-membered oxygen- and nitrogen-containing heterocycles has been regarded as the most fundamental issue in organic chemistry and chemical industry because they are used in producing high-value products. In this study, an efficient, economic, sustainable, and green protocol for multicomponent synthesis has been developed. The one-pot direct Knoevenagel condensation-Michael addition-cyclization sequences for the transformation of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin or phthalhydrazide generate the corresponding dihydropyrano[2,3-c]chromenes and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones over a novel mesoporous metal-organic framework-based supported Cu(II) nanocatalyst [UiO-66@Schiff-Base-Cu(II)] under ambient conditions. Moreover, the [UiO-66@Schiff-Base-Cu(II)] complex efficiently catalyzed the selectively large-scale synthesis of the target molecules with high yield and large turnover numbers. As presented, the catalyst demonstrates excellent reusability and stability and can be recycled up to six runs without noticeable loss of activity. Moreover, ICP-AES analysis showed that no leaching of Cu complex occurred during the recycling process of the heterogeneous [UiO-66@Schiff-Base-Cu(II)] nanocatalyst.

Mono- and bis-pyrazolophthalazines: Design, synthesis, cytotoxic activity, DNA/HSA binding and molecular docking studies

In an attempt to find new potent cytotoxic compounds, several mono- and bis-pyrazolophthalazines 4a-m and 6a-h were synthesized through an efficient, one-pot, three- and pseudo five-component synthetic approach. All derivatives were evaluated for their in vitro cytotoxic activities against four human cancer cell lines of A549, HepG2, MCF-7, and HT29. Compound 4e showed low toxicity against normal cell lines (MRC-5 and MCF 10A, IC₅₀ > 200 µM) and excellent cytotoxic activity against A549 cell line with IC₅₀ value of 1.25 ± 0.19 µM, which was 1.8 times more potent than doxorubicin (IC₅₀ = 2.31 ± 0.13 µM). In addition, compound 6c exhibited remarkable cytotoxic activity against A549 and MCF-7 cell lines (IC₅₀ = 1.35 ± 0.12 and 0.49 ± 0.01 µM, respectively), more than two-fold higher than that of doxorubicin. The binding properties of the best active mono- and bis-pyrazolophthalazine (4e and 6c) with HSA and DNA were fully evaluated by various techniques including UV-Vis absorption, circular dichroism (CD), Zeta potential and dynamic light scattering analyses indicating interaction of the compounds with the secondary structure of HSA and significant change of DNA conformation, presumably via a groove binding mechanism. Additionally, molecular docking and site-selective binding studies confirmed the fundamental interaction of compounds 4e and 6c with base pairs of DNA. Compounds 4e and 6c showed promising features to be considered as potential lead structures for further studies in cancer therapy.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

Heterocycles have been found to be of much importance as several nitrogen- and oxygen-containing heterocycle compounds exist amongst the various USFDA-approved drugs. Because of the advancement of nanotechnology, nanocatalysis has found abundant applications in the synthesis of heterocyclic compounds. Numerous nanoparticles (NPs) have been utilized for several organic transformations, which led us to make dedicated efforts for the complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019. Our emphasize during the coverage of catalyzed reactions of the various MNPs such as Ag, Au, Co, Cu, Fe, Ni, Pd, Pt, Rh, Ru, Si, Ti, and Zn has not only been on nanoparticles catalyzed synthetic transformations for the synthesis of heterocyclic scaffolds, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the synthesis of desired heterocyclic scaffold.

l-Methionine–Pd complex supported on hercynite as a highly efficient and reusable nanocatalyst for C–C cross-coupling reactions

An l-methionine–Pd complex was covalently immobilized on the surface of hercynite (FeAl₂O₄) MNPs, and its catalytic properties were studied in C–C coupling reactions.

Praseodymium(iii) anchored on CoFe2O4 MNPs: an efficient heterogeneous magnetic nanocatalyst for one-pot, multi-component domino synthesis of polyhydroquinoline and 2,3-dihydroquinazolin-4(1H)-one derivatives

CoFe₂O₄@Pr as highly efficient and reusable heterogeneous catalyst prepared by a simple procedure for the synthesis of polyhydroquinoline and 2,3-dihydroquinazolin-4(1H)-one derivatives.