Anchoring of Cu–dimethylglyoxime complex in MCM-41 matrix: a new, recyclable, and highly efficient nanocatalyst for the green preparation of 2,3-dihydroquinazolin-4(1H)-ones

Construction of Indium(III)-Organic Framework Based on a Flexible Cyclotriphosphazene-Derived Hexacarboxylate as a Reusable Green Catalyst for the Synthesis of Bioactive Aza-Heterocycles

The constant demand for eco-friendly methods of synthesizing complex organic compounds inspired researchers to design and develop modern, highly efficient heterogeneous catalytic systems. Herein, In-HCPCP metal-organic framework (SRMIST-1), a heterogeneous Lewis acid catalyst containing less toxic indium and eco-friendly robust cyclotriphosphazene and exhibiting notable chemical and thermal stability, durable catalytic activity, and exceptional reusability was produced through the reaction between indium(III) nitrate hydrate and hexakis(4-carboxylatophenoxy)-cyclotriphosphazene. In the SRMIST-1 structure, secondary building units {InO7} are assembled by a connection of η2- and η1-carboxylic oxo atoms from different HCPCP ligands, forming a three-dimensional network. The occurrence of regularly distributed In(III) sites in SRMIST-1 confers superior reactivity on the catalyst toward the synthesis of 2,3-dihydroquinazolin-4(1H)-ones and 3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxides by the cyclization reaction of 2-aminobenzamides and 2-aminobenzenesulphonamides with aldehydes under optimized reaction conditions, respectively. The notable features of this method include broad functional group compatibility, low catalyst loading (1-5 mol %), mild reaction conditions, easy workup procedures, good to excellent reaction yields, ethanol as a green solvent, reusability of the catalyst (five cycles), and economic attractiveness, which is mainly due to sustainability of SRMIST-1 as a reusable green catalyst. Our findings demonstrate that the highly reactive and reusable green catalyst finds widespread applications in medicinal chemistry.

Zn Complex on Tryptophan-Functionalized MCM-41 as an Efficient and Promising Reusable Nanocatalyst in One-Pot Three-Component Synthesis of Amino Benzyl Quinolinols and Naphthols via a Betti Reaction

In this research, a Zn transition metallic complex on functionalized mesopore silica MCM-41 has been designed and utilized as an effective, recoverable, and thermally stable heterogeneous nanocatalyst in the formation of the C-C bond. Also, the synthesis of amino benzyl quinolinols and amino benzyl naphthol derivatives was performed by the three-component reaction of Betti from aromatic aldehydes, type II amines, and 8-hydroxyquinoline and 1-naphthol in the presence of the MCM-41-tryptophan-Zn nanocatalyst under reflux conditions. The short reaction times, high efficiency of the products, the easy separation of catalysts due to their heterogeneity, and their reusability are the advantages of this method. Finally, the nature of catalysts was studied by using some techniques such as the Fourier transform infrared spectrum, energy-dispersive spectroscopy, hot filtration test, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, inductively coupled plasma optical emission spectrometry, and N₂ adsorption-desorption (BET). The synthesized heterogeneous catalysts showed perfect catalytic activity and also good recyclability in the Betti reaction. They could be reused at least for five consecutive cycles without significant loss of their catalytic activities.