Sustainable Catalytic Process with a High Eco-Scale Score for the Synthesis of Five-, Six-, and Seven-Membered Heterocyclic Compounds Using Nanocrystalline Zeolites

Synthesis and evaluation of a Zn-Al layered double hydroxide for the removal of ochratoxin A. Greenness assessment

The retention behavior of a dangerous toxin, ochratoxin A (OTA), present in food samples and derivatives was evaluated using Layered Double Hydroxides (LDHs). This nanomaterial composed mostly of zinc and aluminum was synthesized by the co-precipitation method and the obtained solid was characterized by different techniques, such as XRD, FTIR, TGA, SEM, and N₂ adsorption-desorption isotherms. Experimental conditions were optimized by chemometric tools. Ochratoxin A determination was performed using an ultra-high-performance liquid chromatography (UHPLC) system coupled to tandem mass spectrometry. From the findings, quantitative removal of the mycotoxin was achieved. Thus, a novel, nanostructured, innocuous, low-cost, easily synthesized material, such as the Zn-Al layered double hydroxide, is proposed for ochratoxin A removal. This might represent an effective and sustainable approach with potential applications to different types of food and feed samples.

An overview of quinoxaline synthesis by green methods: recent reports

Quinoxalines and their derivatives belong to an important class of bicyclic aromatic heterocyclic system, also known as benzopyrazines, containing a benzene ring and a pyrazine ring. They have attracted considerable attention over the years due to their potential biological and pharmaceutical properties. A wide range of synthetic strategies is reported in this significant area of research. The present review showcases recent research advances in the synthesis of quinoxaline derivatives following environmentally benign approaches.

Oxidant/Solvent-Controlled I2-Catalyzed Domino Annulation for Selective Synthesis of 2-Aroylbenzothiazoles and 2-Arylbenzothiazoles under Metal-Free Conditions

A simple and practical domino protocol for the selective synthesis of 2-aroylbenzothiazoles and 2-aryl benzothiazoles catalyzed by I₂ is developed under metal-free conditions. The reaction outcomes are exclusively controlled by the reaction oxidant/medium. With DMSO employed as both the solvent and the oxidant, an oxidation of aromatic methyl ketones takes precedence over the condensation with 2-aminobenzenethiols. On the other hand, when the reaction was carried out in PhNO₂ or in 1,4-dioxane containing PhNO₂, the condensation of aromatic methyl ketones with 2-aminobenzenethiols has priority to form imines which is followed by an oxidation of the methyl group from ketones to afford 2-arylbenzothiazoles as a sole product. The PhNO₂/I₂ co-catalytic system is proposed first time.

Bonded- and discreted-Lindqvist hexatungstate-based copper hybrids as heterogeneous catalysts for the one-pot synthesis of 2-phenylquinoxalines via 2-haloanilines with vinyl azides or 3-phenyl-2H-azirines

One bonded- and one discreted-Lindqvist hexatungstate-based copper hybrids (Cu-POMs) ([Cu2(O)OH(phen)2]2[W6O19]·6H2O (1) and [Cu2(phen)4Cl] [HW6O19]·2H2O (2) (phen = 1,10-phenanthroline)) were controllably synthesized and routinely characterized. Cu-POMs 1-2 consisted of identical [W6O19] unit and similar copper-phen complexes, the two units are bonded via four Cu-O chemical bonds in compound 1; however, compound 2 is discreted and stabilized by intermolecular electrostatic interactions. Importantly, these Cu-POMs catalysts were first applied in the novel reaction for the preparation of 2-phenylquinoxalines via the one-pot coupling and oxidation reactions of 2-haloanilines with vinyl azides or 3-phenyl-2H-azirines under mild conditions, and Cu-POMs 1 showed higher catalytic performance in good yields (79-84%). The reactions exhibit some functional group tolerance and allow for the preparation of a number of 2-phenylquinoxalines.

Direct synthesis of novel quinoxaline derivatives via palladium-catalyzed reductive annulation of catechols and nitroarylamines

A palladium-catalyzed new hydrogenative annulation reaction of catechols and nitroarylamines, allowing straightforward access to two classes of novel quinoxaline derivatives, has been demonstrated.