Catalytic application of a nano-molten salt catalyst in the synthesis of biological naphthoquinone-based compounds

Synthesis and Characterization of a Hercynite-Supported Copper(II) Complex Based on 1,10-Phenanthroline-5,6-dione and Acetylacetone Building Blocks and Its Catalytic Application in Annulation Reactions

In the present work, a novel Cu(II) complex containing 10-phenanthroline-5,6-dione (phen-dione) and acetylacetone (acac) was prepared via solid-phase synthesis on silica-modified hercynite magnetic nanoparticles (MNPs). The resulting structure underwent thorough structural analysis using diverse instrumental techniques. The catalytic potential of the synthesized Cu(II) complex was successfully demonstrated in the synthesis of 2-amino-3-cyano-4H-chromenes. This was accomplished via a one-pot, three-component condensation reaction involving lawsone, malononitrile, and aromatic aldehydes in ethanol under reflux conditions, leading to remarkably high yields and product purity. Several advantages stem from this investigation. Notably, the use of ethanol as a sustainable and environmentally friendly solvent highlights the ecoconscious approach of this research. Moreover, the reaction conditions were mild and the separation process was straightforward, resulting in reduced byproducts as well as time and cost savings. Furthermore, the catalyst's stability and reusability were studied under optimal conditions, revealing excellent reversibility for up to five cycles without any significant loss of activity. This excellent performance underscores the potential of the Cu(II) complex for sustainable catalytic applications.

Construction of a Dual-Functionalized Acid-Base Nanocatalyst via HEPES Buffer Functionalized on Fe3O4 as a Reusable Catalyst for Annulation Reactions

Herein, we present a highly efficient dual-functionalized acid-base nanocatalyst, denoted as Fe3O4@GLYMO-HEPES, featuring sulfuric acid and tertiary amines as its dual functional components. This catalyst is synthesized through the immobilization of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) as the source of these functionalities onto magnetite (Fe3O4) using 3-glycidoxypropyltriethoxysilane (GLYMO) as a linker. Characterization studies confirm the integrity of the Fe3O4 core, with the GLYMO-HEPES coating exhibiting no phase changes. Furthermore, Fe3O4@GLYMO-HEPES nanoparticles demonstrate a uniform size distribution without aggregation. Notably, the catalyst exhibits remarkable stability up to 200 °C and possesses a saturation magnetization value of 31.5 emu/g, facilitating easy recovery via magnetic separation. These findings underscore the potential of Fe3O4@GLYMO-HEPES as a versatile and recyclable nanocatalyst for various applications. Its catalytic ability was evaluated in the synthesis of various pyrano[2,3-c]pyrazoles and 2-amino-3-cyano-4H-chromenes through a tandem Knorr-Knoevenagel-Michael-Thorpe-Ziegler-type heterocyclization mechanism, using different aldehydes. A wide range of fused heterocycles was synthesized having good to excellent yields. The process is cost-effective, safe, sustainable, and scalable, and the catalyst can be reused up to five times. The prepared catalyst was found to be highly stable and heterogeneous and showed good recyclability.

Application of novel metal-organic framework [Zr-UiO-66-PDC-SO3H]FeCl4 in the synthesis of dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives

In the current paper, we produce a new metal-organic framework (MOF) based on Zr metal, [Zr-UiO-66-PDC-SO3H]FeCl4, via an anion exchange method, which is fully characterized by FT-IR, SEM with elemental mapping and EDX, FE-SEM and TEM. Furthermore, the use of [Zr-UiO-66-PDC-SO3H]FeCl4 as a porous catalyst was examined for the one-pot synthesis of novel dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives by reaction of 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione, 2-hydroxynaphthalene-1,4-dione and various aldehydes at 100 °C with good to excellent yields.

A highly efficient and green protocol for the synthesis of 3,3′-(arylmethylene)-bis(2-hydroxynaphthoquinone) derivatives catalyzed by a dicationic molten salt

A highly efficient and green protocol for the synthesis of 3,3′-(arylmethylene)-bis(2-hydroxynaphthoquinone) {3,3′-(arylmethylene)-bis(2-hydroxynaphthalene-1,4-dione)} derivatives has been developed. The reaction of 2-hydroxynaphthoquinone (2-hydroxynaphthalene-1,4-dione) (2 eq.) and arylaldehydes (1 eq.) in the presence of the dicationic molten salt N,N,N′,N′-tetramethylethylenediaminium bis-hydrogensulfate ([TMEDAH2][HSO4]2) under solvent-free conditions afforded the mentioned compounds in high yields and relatively short reaction times.