Current Catalysis - Current Issue

The emergence of enantioselective organocatalysis as a potent synthetic chemistry strategy that supports metal-catalyzed transformations has resulted in the creation of novel procedures for the synthesis of various chiral molecules. Organocatalysis is a desirable method for creating complex molecular structures due to its many benefits, including its ease of use, wide availability of catalysts and low toxicity. Chemists are actively exploring synthetic methodologies and looking into the applications of pyrrolidine-based organocatalysts. The application of organocatalysts spans a wide range of reaction types, highlighting their ability to participate in a variety of catalytic processes. The current study offers a succinct summary of the principal strategic methods for producing pyrrolidine-based organocatalysts and demonstrating their usefulness in organic transformations.

Aims: The Isocyanides based Multi-component reactions (IMCRs), and Passerini reactions were performed by using GaCl3 and PEG-400 media to generate a library of new scaffolds. Background: The Isocyanides Multi-component reactions (IMCRs) have proven their importance due to their major advantages in synthetic and medicinal areas. Among various IMCRs, Passerini stands for their pertinency in the novel adducts articulation and generates an amide functionality which shows unbeatable efficiency towards the generation of lead scaffolds. In the research fields, PEG is acting as a versatile greener solvent due to its beneficial economic advantages. In general, chiral-based separation is always a headache for the chemist and researchers tend to generate routes with major products such as single isomers. Most MCRs studied with metal-based synthesis and rather use Au or Pt-based catalyst, Gallium that has been widely explored in chiral Lewis acid catalysis, organo-catalysis, or cooperative catalysis to generate a library of compounds with high stereoselectivity with mild reaction conditions. Objective: To find diverse scaffolds in the field of organic chemistry using easily accessible metal catalysts. Methods: In this article, Enantiomerically pure, 2-(((1H-benzo[d][1,2,3]triazol-1-yl)methyl)amino)-2-oxo-1-substitutedphenylethyl pyrazine-2-carboxylate (4a-4j), produced through a three-component passerine coupling reaction under GaCl3 as a Lewis acid-promoted conditions with diastereoseletivity ranging from moderate to good. Results: The designed approach exhibited an in situ single-step-economical path to enantiomerically pure, α-acyloxy carboxamides with pyrazine and 1H-benzo[d][1,2,3]triazole fragments employing the greener way of media through “PEG-400”. In an anti-TB screening against H37Rv, the withdrawing groups showed excellent activity compared to the donating groups. Conclusion: It was expected that the Lewis acid-PEG pairs could serve as the best catalytic transformations in eco-friendly ways and enrich the pure enantiomer of the adduct. On the medicinal side, the isolated library of compounds was screened for their biological activity against “Mycobacterium Tuberculosis H37Rv” and 4f featuring “4-F” as a substituent was found to be most active (MIC: 12.5 μg/mL).

Introduction: The catalytic activity of metallic nanomaterials depends on their surface morphology. A widely known method is the laser synthesis of metal nanostructures by depositing on dielectric surfaces from aqueous solutions containing metal complexes. The article analyzes the factors that favor the production of conductive, catalytic, and sensory-active deposits by laser method. It is shown that the two main factors is the presence of a large number of charged defects on heterophase surfaces and the structure of metal-containing complexes in solution. This is typical for mono- and bimetallic alloys, the components of which interact with the laser beams according to the autocatalytic type. Using the example of laser deposition from solutions of Co, Ni, Fe, Zn, and Ag salts with homo- and heterophase dielectrics, the sensory and catalytic properties of the deposits are compared by impedance spectroscopy and voltammetry. It has been shown that heterophase precipitation significantly enhances the catalysis response. Background: It is known that the highest catalytic activity exhibits nanostructured and highly porous materials with a large specific surface area and materials containing surface heterogeneity in the form of charged acid-base centers. Such materials are necessary for the creation of new catalysts for organic synthesis and for the creation of new sensor materials for enzyme-free microbiosensors. Active development of new methods for the synthesis of such materials is underway. But not all of them give the expected result. Methods: Laser synthesis methods have the best prospects, including the method of laser-induced metal deposition. This is the laser synthesis of metal nanostructures by depositing dielectric surfaces from aqueous solutions containing metal complexes. Results: Ц#144;rticle analyzes the factors that favor the production of conductive, catalytic, and sensory-active deposits by laser method. It is shown that the two main factors are the presence of a large number of charged defects on heterophase surfaces and the structure of a metal-contained complex in solution. This is typical for mono- and bimetallic alloys, the components of which interact with the laser beam according to the autocatalytic type. Using the example of laser deposition from solutions of Co, Ni, Fe, Zn, and Ag salts with homo- and heterophase dielectrics, the sensory and catalytic properties of the deposits are compared by impedance spectroscopy and voltammetry. Conclusion: It has been shown that heterophase precipitation significantly enhances the catalysis response. It is shown that the laser deposition reaction has an autocatalytic mechanism in a dynamic mode. The results of autocatalysis can be used in a stationary mode to create a microbiosensor for glucose, as well as to create a technology for laser refining rare metals and hydrogen energy in a dynamic mode.

Background: In recent years, bimetallic nanoparticles have gained remarkable attention due to their excellent physical and chemical properties. Especially, bimetallic nanoparticles are found to be highly efficient as catalysts in many important organic transformations. Objective: The objective of the present work involves green synthesis of Au-Ni bimetallic nanoparticles using plant extract as the bio-reductant and to evaluate their catalytic efficiency in oxidation of alcohols. Methods: The experiment involves a simple and eco-friendly protocol for synthesis of Au-Ni bimetallic as well as their corresponding monometallic nanoparticles that involves the use of aqueous fruit seed extract of Coccinia grandis(L.) Voigt as the bio-reductant and tannic acid as the bio-stabilizer. The synthesized nanoparticles were characterized by using XRD, TEM, FTIR, TGA etc., and their catalytic activity was evaluated for oxidation of alcohols. Results: The synthesized bimetallic nanoparticles have shown excellent catalytic activity towards aqueous phase oxidation of alcohols to aldehydes under ambient reaction conditions. Furthermore, the results have revealed better effective performance of the bimetallic nanoparticles over the corresponding monometallic nanoparticles of gold and nickel, establishing the synergic influence of the two metals. Another attractive feature of this work is that the Au-Ni bimetallic nanoparticles could be recycled and reused up to four catalytic cycles without any significant decline in product yield. Conclusion: The green synthesized bimetallic Au-Ni nanoparticles have shown excellent catalytic activity toward the oxidation of alcohols in aqueous media under ambient reaction conditions. In addition, the nanoparticles are found to be successfully recyclable upto four catalytic cycles.