Cu/Graphene/Clay Nanohybrid: A Highly Efficient Heterogeneous Nanocatalyst for Synthesis of New 5-Substituted-1H-Tetrazole Derivatives Tethered to BioactiveN-Heterocyclic Cores

A new Schiff base 2-benzoylpyridine-based copper complex on boehmite nanoparticles as a recoverable nanocatalyst for the homoselective synthesis of 5-substituted tetrazoles

In this study, boehmite nanoparticles (B-NPs) were prepared by a simple process and then their surface was modified by (3-aminopropyl)triethoxysilane (3-APTES). The modified B-NPs (3-APTES@B-NPs) were functionalized by 2-benzoylpyridine Schiff-base ligand toward the immobilization of the Schiff-base 2-benzoylpyridine ligand on the 3-APTES@B-NPs's surface (2BP-Schiff-base@B-NPs). Finally, copper ions were coordinated with the supported Schiff-base ligand on B-NPs toward the formation of the final catalyst (Cu-2BP-Schiff-base@B-NPs). The prepared Cu-2BP-Schiff-base@B-NPs were characterized using FT-IR spectroscopy, BET analysis, XRD, SEM, AAS, TGA, EDX and elemental mapping. Further, Cu-2BP-Schiff-base@B-NPs were applied as a homoselective and recyclable catalyst for the synthesis of a diverse range of 5-substituted tetrazoles in PEG-400 as a green solvent. The main benefits of this protocol are high homoselectivity attributes, short reaction times, high product yields and TOF values, and further addition to the catalyst ability to be recycled at least four times without significantly losing catalytic efficiency.

Nanomaterial catalyzed green synthesis of tetrazoles and its derivatives: a review on recent advancements

Tetrazoles are indispensable nitrogen containing heterocyclic scaffolds that offer a broad spectrum of applications in various domains such as medicinal chemistry, high energy material science, biochemistry, pharmacology etc. Owing to their useful applications, a wide range of catalysts have been explored for green synthesis of tetrazole derivatives. In recent times, nanomaterials have been emerged as extremely efficient catalysts for different organic transformations because of their high surface area-to-volume ratio, easy surface modification, simple fabrications, easy recovery and reusability. In this article, we have presented an overview of utilization of various nano-catalysts, nanocomposites and other solid-supported nanomaterials as an efficient environmental benign catalytic system for green synthesis of tetrazoles and derivatives. This review will provide an exclusive emphasis on boehmite, magnetic, copper, carbon, MCM-41, and composite based nanomaterials that have been developed since the year 2010 for the synthesis of tetrazole derivatives. In addition, we have briefly discussed the fabrication, functionalization and characterization of some novel nanomaterials and their advantages in the synthesis of tetrazole and its derivatives along with the reaction mechanism that involves synthesis of tetrazole derivatives via nanomaterials catalysed reactions.

Emerging Trends in the Syntheses of Heterocycles Using Graphene-based Carbocatalysts: An Update

Graphene-based carbocatalysts owing to numerous amazing properties such as large specific surface area, high intrinsic mobility, excellent thermal and electrical conductivities, chemical stability, ease of functionalization, simple method of preparation, effortless recovery and recyclability have gained a superior position amongst the conventional homogeneous and heterogeneous catalysts. In this review, an endeavor has been made to highlight the syntheses of diverse heterocyclic compounds catalyzed by graphene-based catalysts. Further, the study also reveals that all the catalysts could be reused several times without significant loss in their catalytic activity. Additionally, most of the reactions catalyzed by graphene-based carbocatalysts were carried out at ambient temperature and under solvent-free conditions. Thus, the graphene-based catalysts do not merely act as efficient catalysts but also serve as sustainable, green catalysts. This review is divided into various sub-sections, each of which comprehensively describes the preparation of a particular heterocyclic scaffold catalyzed by graphene-derived carbocatalyst in addition to synthesis of graphene oxide and reduced graphene oxide, functionalization, and structural features governing their catalytic properties. Synthesis of heterocycles catalyzed by graphene-based carbocatalysts.