Mechanochemical Approach towards Multi-Functionalized 1,2,3-Triazoles and Anti-Seizure Drug Rufinamide Analogs Using Copper Beads

Highly regiospecific, copper-salt-free and neat conditions have been demonstrated for the 1,3-dipolar azide-alkyne cycloaddition (AAC) reactions under mechanochemical conditions. A group of structurally challenging alkynes and heterocyclic derivatives was efficiently implemented to achieve highly functionalized 1,4-disubstituted-1,2,3-triazoles in good to excellent yield by using the Cu beads without generation of unwanted byproducts. Furthermore, the high-speed ball milling (HSBM) strategy has also been extended to the synthesis of the commercially available pharmaceutical agent, Rufinamide, an antiepileptic drug (AED) and its analogues. The same strategy was also applied for the synthesis of the Cl-derivative of Rufinamide. Analysis of the single crystal XRD data of the triazole was also performed for the final structural confirmation. The Cu beads are easily recoverable from the reaction mixture and used for the further reactions without any special treatment.

Graphene supported CoO nanoparticles as an advanced catalyst for aerobic oxidation of cyclohexane

Transition metals are commonly employed as catalysts for the oxidation of cyclohexane.

Cu/SiO2-Pr-NH-Benz as a novel nanocatalyst for the efficient synthesis of 1,4-disubstituted triazoles and propargyl amine derivatives in an aqueous solution

In this work, an innovative nanocatalyst (Cu/SiO₂-Pr-NH-Benz) was synthesized and applied to coupling and click reaction in an aqueous solution. This work reports an efficient and straightforward approach for synthesizing diverse propargylamine and 1,2,3-triazole derivatives in excellent yield and short-time reaction. Also, a novel method involving the Cu NPs supported on the SiO₂ nanocatalyst as a heterogeneous novel catalyst for the “one-pot” three-component A³-coupling of aldehyde, amine, and alkynes and “one-pot” click reaction between alkyne, benzyl halide, and sodium azide in the water at room temperature was developed. Significant advantageous such as enhanced catalytic activity with efficient recycling for the one-pot synthesis of 1,4-disubstituted triazoles and propargyl amine derivatives and in green condition were observed. Also, after five successive reactions, the catalytic activity of recycled Cu/SiO₂-Pr-NH-Benz remained high without significant loss in its intrinsic activity.

Regitz Diazo Transfer Reaction for the Synthesis of 1,4,5-Trisubstituted 1,2,3-Triazoles and Subsequent Regiospecific Construction of 1,4-Disubstituted 1,2,3-Triazoles via C-C Bond Cleavage

A straightforward and efficient methodology has been developed for the synthesis of 1,4,5-trisubstituted dicarbonyl 1,2,3-triazoles and 1,4-disubstituted sole-carbonyl 1,2,3-triazoles via a C-C bond cleavage process. The Regitz diazo transfer and C-C bond cleavage were the key steps of this transformation, which provided diverse carbonyl-substituted structural 1,2,3-triazoles. This reaction featured with excellent regioselectivity, wide functional group tolerance, and mild conditions.

Exploiting a silver–bismuth hybrid material as heterogeneous noble metal catalyst for decarboxylations and decarboxylative deuterations of carboxylic acids under batch and continuous flow conditions

A silver-containing hybrid material is reported as a heterogeneous noble metal catalyst for protodecarboxylations and decarboxylative deuterations of carboxylic acids.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

Heterocycles have been found to be of much importance as several nitrogen- and oxygen-containing heterocycle compounds exist amongst the various USFDA-approved drugs. Because of the advancement of nanotechnology, nanocatalysis has found abundant applications in the synthesis of heterocyclic compounds. Numerous nanoparticles (NPs) have been utilized for several organic transformations, which led us to make dedicated efforts for the complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019. Our emphasize during the coverage of catalyzed reactions of the various MNPs such as Ag, Au, Co, Cu, Fe, Ni, Pd, Pt, Rh, Ru, Si, Ti, and Zn has not only been on nanoparticles catalyzed synthetic transformations for the synthesis of heterocyclic scaffolds, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the synthesis of desired heterocyclic scaffold.

Shedding light on the use of Cu(ii)-salen complexes in the A3 coupling reaction

One Cu(ii) complex, {Cu(ii)L} (1S), has been synthesised, in two high yielding steps under ambient conditions, and characterised by single-crystal X-Ray diffraction (SXRD), IR, UV-Vis, circular dichroism (CD), elemental analysis, thermogravimetric analysis (TGA) and electron spray ionization mass spectroscopy (ESI-MS). This air-stable compound enables the generation, at room temperature and in open-air, of twenty propargylamines, nine new, from secondary amines, aliphatic aldehydes and alkynes with a broad scope with yields up to 99%. Catalyst loadings can be as low as 1 mol%, while the recovered material retains its structural integrity and can be used up to 5 times without loss of its activity. Control experiments, SXRD, cyclic voltammetry and theoretical studies shed light on the mechanism revealing that the key to success is the use of phenoxido salen based ligands. These ligands orchestrate topological control permitting alkyne binding with concomitant activation of the C-H bond and simultaneously acting as a template temporarily accommodating the abstracted acetylenic proton, and continuously generating, via in situ formed radicals and a Single Electron Transfer (SET) mechanism, a transient Cu(i) active site to facilitate this transformation. The scope and limitations of this protocol are discussed and presented.

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.

Ag–NHC anchored on silica: an efficient ultra-low loading catalyst for regioselective 1,2,3-triazole synthesis

A silica-supported silver complex, Ag–NHC@SiO₂, was prepared by an anchoring coordination technique, which was successfully employed for the click reaction under mild reaction conditions.

A facile synthesis methodology for preparation of Ag-Ni-reduced graphene oxide: a magnetically separable versatile nanocatalyst for multiple organic reactions and density functional study of its electronic structures

Here, we report a simple 'in situ' co-precipitation reduction synthesis method for the preparation of nanocatalysts composed of Ag, Ni nanoparticles, and reduced graphene oxide (RGO). First-principles calculations based on Density Functional Theory (DFT) were performed to obtain the electronic structures and properties of Ag-Ni-graphene superlattice and to understand the interfacial interactions which exist at the interface between Ag, Ni, and graphene. The catalytic performance of the synthesized catalysts (Ag x Ni(1-x)) y RGO(100-y) were evaluated for four reactions (i) reduction of 4-nitrophenol (4-NP) in the presence of excess NaBH4 in aqueous medium, (ii) A3 coupling reaction for the synthesis of propargylamines, (iii) epoxidation of styrene, and (iv) 'Click reaction' for the synthesis of 1,2,3-triazole derivatives. For all of these reactions the catalyst composed of Ag, Ni, and RGO, exhibited significantly higher catalytic activity than that of pure Ag, Ni, and RGO. Moreover, an easy magnetic recovery of this catalyst from the reaction mixture after completion of the catalytic reactions and the good reusability of the recovered catalyst is also reported here. To the best of our knowledge, this is the first time the demonstration of the versatile catalytic activity of (Ag x Ni(1-x)) y RGO(100-y) towards multiple reactions, and the DFT study of its electronic structure have been reported.

Recent progress of metal-graphene nanostructures in photocatalysis

Metal-graphene nanostructures (NSs) as photocatalysts, prepared using simple and scalable synthesis methods, are gaining heightened attention as novel materials for water treatment and environmental remediation applications. Graphene, the unique few layers sheet-like arrangement of sp2 hybridized carbon atoms, has an inimitable two-dimensional (2D) structure. The material is highly conductive, has high electron mobility and an extremely high surface area, and can be produced on a large scale at low cost. Accordingly, it has been considered as an essential base component for producing various metal-based NSs. In particular, metal-graphene NSs as photocatalysts have attracted considerable attention because of their special surface plasmon resonance (SPR) effect that can improve their performance for the removal of toxic dyes and other pollutants. This review summarizes the recent and advanced progress for the easy fabrication and design of graphene-based NSs as photocatalysts, as a novel tool, using a range of approaches, including green and biogenic approaches.

A mineralogically-inspired silver–bismuth hybrid material: an efficient heterogeneous catalyst for the direct synthesis of nitriles from terminal alkynes

A silver-containing hybrid material is reported as an effective heterogeneous catalyst for the direct synthesis of organic nitriles from terminal alkynes.

Crosslinked chitosan nanoparticle-anchored magnetic multi-wall carbon nanotubes: a bio-nanoreactor with extremely high activity toward click-multi-component reactions

In the present study, we have designed a procedure for the synthesis of a bio-nanoreactor catalyst, crosslinked chitosan nanoparticle-anchored magnetic multi-wall carbon nanotubes (CS NPs/MWCNT@Fe₃O₄), via an in situ ionotropic gelation method.

A nano silver-xerogel (Ag nps@modified TEOS) as a newly developed nanocatalyst in the synthesis of benzopyranopyrimidines (with secondary and primary amines) and gem-bisamides

Silver nanoparticles have been prepared from a chemical reduction approach and supported on modified TEOS (tetraethylorthosilicate) xerogel to be studied as a nanocatalyst.