Magnetically recoverable Fe3O4@SiO2@SBA-3@2-ATP-Cu: an improved catalyst for the synthesis of 5-substituted 1H-tetrazoles

Functionalization of Fe3O4@SiO2@SBA-3 with double-charged 3-chloropropyltrimethoxysilane (CPTMS) and 2-aminophenol, followed by mechanical mixing of the solid product with copper(i) chloride produces a new, greener and efficient Fe3O4@SiO2@SBA-3@2-ATP-Cu catalyst for the synthesis of 5-substituted 1H-tetrazoles. XRD, SEM, atomic absorption, TGA, N2 adsorption-desorption, and VSM analyses were performed for the characterization of the Fe3O4@SiO2@SBA-3@2-ATP-Cu structure. Nitrogen adsorption-desorption analysis revealed that Fe3O4@SiO2@SBA-3@2-ATP-Cu has a surface area of 242 m2 g-1 and a total pore volume of 55.72 cm3 g-1. In synthesizing 5-substituted 1H-tetrazoles, Fe3O4@SiO2@SBA-3@2-ATP-Cu shows superior yields in short reaction times at 120 °C. This catalyst also showed high thermal stability and recyclability at least for 4 runs without apparent loss of efficiency.

Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu: preparation, characterization, and catalytic performance in the conversion of nitriles to amides and the synthesis of 5-substituted 1H-tetrazoles

A novel, efficient, and recyclable mesoporous Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu nanocatalyst was synthesized by grafting l-arginine (with the ability to coordinate with Cu) onto a mixed phase of a magnetic mesoporous SBA-3 support. The catalyst was characterized using several techniques, including Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), X-ray diffraction (XRD) analysis, N2 adsorption-desorption analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) analysis, and atomic absorption spectroscopy (AAS). The resulting solid material possessed a surface area of 145 m2 g-1 and a total pore volume of 34 cm3 g-1. The prepared mesoporous material was studied as a practical, recyclable, and chemoselective catalyst in some organic functional group transformations such as the conversion of nitriles to amides and synthesis of 5-substituted 1H-tetrazoles. This novel magnetic nanocatalyst proved to be effective and provided the products in high to excellent yields under green solvent conditions. Meanwhile, the as-prepared Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu demonstrated excellent reusability and stability under reaction conditions, and its catalytic activity shown only a slight decrease after seven consecutive runs. Therefore, the as-synthesized magnetic Fe3O4@SiO2@SBA-3@CPTMS@Arg-Cu has broad prospects for practical applications, and offers various benefits such as simplicity, nontoxicity, low cost, simple work-up, and an environmentally benign nature.

Nickel-Catalyzed Decarbonylative Amination of Carboxylic Acid Esters

The reaction of carboxylic acid derivatives with amines to form amide bonds has been the most widely used transformation in organic synthesis over the past century. Its utility is driven by the broad availability of the starting materials as well as the kinetic and thermodynamic driving force for amide bond formation. As such, the invention of new reactions between carboxylic acid derivatives and amines that strategically deviate from amide bond formation remains both a challenge and an opportunity for synthetic chemists. This report describes the development of a nickel-catalyzed decarbonylative reaction that couples (hetero)aromatic esters with a broad scope of amines to form (hetero)aryl amine products. The successful realization of this transformation was predicated on strategic design of the cross-coupling partners (phenol esters and silyl amines) to preclude conventional reactivity that forms inert amide byproducts.

Cu(I)–PNF, an organic-based nanocatalyst, catalyzed C–O and C–S cross-coupling reactions

Peptide nanofiber has been prepared via a self-assembly protocol and decorated with Cu(I) to prepare a nanostructural catalyst. The catalytic activity of this prepared nanomaterial (Cu(I)–PNF) was examined in C–O and C–S cross-coupling reactions. Compared with conventional copper–ligand catalytic systems, CuNP–PNF has unique advantages such as water solubility, high efficiency, and low cost, which makes it a highly efficient and beneficial catalyst to reuse in cross-coupling reactions.

Sustainable Generation of Ni(OH)2 Nanoparticles for the Green Synthesis of 5-Substituted 1H-Tetrazoles: A Competent Turn on Fluorescence Sensing of H2O2

A mutually correlated green protocol has been devised that originates from a sustainable production of β-Ni(OH)₂ nanoparticles which is used for an efficient catalytic synthesis of versatile substituted tetrazoles, under mild reaction conditions in water via a simple, one-pot, eco-friendly method. The synthesis is followed by derivatization into a highly fluorescence active compound 9-(4-(5-(quinolin-2-yl)-1H-tetrazol-1-yl)phenyl)-9H-carbazole that can be used at tracer concentrations (0.1 μM) to detect as well as quantify hydrogen peroxide down to 2 μM concentration. The nanocatalyst was synthesized by a simple, proficient, and cost-effective methodology and characterized thoroughly by UV-vis absorption and Fourier transform infrared spectra, N₂ adsorption/desorption, high resolution transmission electron microscopy, powder X-ray diffraction pattern, field emission scanning electron microscopy, and thermogravimetric analysis. Broad substrate scope, easy handling, higher efficiency, low cost, and reusability of the catalyst are some of the important features of this heterogeneous catalytic system. The strong analytical performance of the resultant derivative in low-level quantification of potentially hazardous hydrogen peroxide is the key success of the overall green synthesis procedure reported here.