Aggregates of perylene bisimide stabilized superparamagnetic Fe3O4 nanoparticles: an efficient catalyst for the preparation of propargylamines and quinolines via C-H activation

Magnetic nanoparticle-catalysed synthesis of quinoline derivatives: A green and sustainable method

Greener and sustainable synthetic strategies have been evolving as the demanding domain of organic synthesis during the last decade. Green synthesis involves the development of method that decrease or eliminate the use of hazardous chemicals, and make use of renewable or recyclable resources. By incorporating the fundamentals and methodologies of green synthesis, organic chemists have the ability to develop valuable organic molecular frameworks which also demonstrate a strong commitment to environmental sustainability. In this context, the nanoparticle has garnered significant interest due to its various features, adhering to the principles of green synthesis. Specifically, magnetic nanoparticles have been trending extensive uses in green synthesis throughout the past decade. The role of magnetic nanoparticle has an irreplaceable place in the synthesis of biologically valuable frameworks named as quinoline. Quinoline are considered a privileged structure among organic compounds and offer a promising avenue for identifying lead structures in the search of new synthetic molecules (Saquinavir, Imiquimod and Reabamipide) having potential medicinal values and other important prospects. So, it's always indeed to the organic and medicinal chemist to develop biologically active frameworks by the green synthesis. The current manuscript consolidates the existing research on properties of environment-friendly magnetic nanoparticles for generating an extended range of valuable quinoline derivatives.

Quinoline Synthesis: Nanocatalyzed Green Protocols-An Overview

Heterocyclic compounds are of great interest in our daily lives. They are widely distributed in nature and are synthesized in laboratories. Heterocycles play an important role in the metabolism of all living cells, including vitamins and coenzyme precursors like thiamine and riboflavin. Furthermore, heterocyclic systems are essential building blocks for creating innovative materials with intriguing electrical, mechanical, and biological properties. Also, more than 85% of all biologically active chemical entities comprise a heterocycle. As a result, heterocycle synthesis piqued researchers' curiosity, and in recent decades, chemists have concentrated more on nitrogen-containing cyclic nuclei in structures. Quinoline and its derivatives exhibit several biological functions, including antimicrobial, anticancer, antimalarial, anti-inflammatory, antihypertensive, and antiasthmatic effects. In addition, over a hundred quinoline-based drugs are available to treat a variety of disorders. Because of its biological importance, researchers developed one-pot synthetic methods employing effective acid/base catalysts (Lewis acids, Brønsted acids, and ionic liquids), reagents, and transition-metal-based catalysts. These methods have some downsides, including longer reaction times, harsher reaction conditions, creation of byproducts, costly catalysts, use of hazardous solvents, an unacceptable economic yield, and catalyst recovery. Researchers' focus has switched to creating environmentally friendly and effective methods for the synthesis of quinoline derivatives as a result of these methodologic shortcomings. Because of its special qualities, the use of nanocatalysts or nanocomposites offers an option for the effective synthesis of quinolines. This review focuses on the published research articles on nanocatalysts to synthesize substituted quinoline derivatives. This review covers all contributions until May 2024, focusing on quinoline ring building and mechanistic issues. With the aid of this review, we anticipate that synthetic chemists will be able to develop more effective methods of synthesizing quinolines.

Yolk-Shell Au NPs@Carbon Porous Nanoreactors Derived from ZIF-8: A High-Efficiency Catalyst for Three-Component Coupling Reaction

A yolk-shell Au NPs@carbon porous nanoreactor with an active gold (Au) core and a porous carbon shell has been fabricated and demonstrates excellent high activity and cyclic stability as a heterogeneous catalyst for the three-component coupling reaction of aldehyde, amine, and alkyne. Remarkably, the unique yolk-shell nanostructure can protect gold nanoparticles (Au NPs) from aggregation, allow for efficient mass transport, and benefit substrate enrichment, giving rise to enhanced activity, stability, and recyclability.

Perylene-Based Smart Fluoroprobe with Dual Function: Ratiometric Response toward Hazardous Organic Peroxides and Pure White Light Generation via Self-Assembly

In this report, we have designed and synthesized a perylene-based smart fluoroprobe (PBE) in which the perylene core has been functionalized with the boronate group at the peri-position. PBE shows a very fast and ratiometric response toward harmful organic peroxides (OPs) generated in old ethereal solvents via auto-oxidation. The response toward OPs takes place with a visible color change from green to yellow, which could be easily observed with the naked eye. The reaction between PBE and OPs involves the cleavage of the boronate group and its consequent conversion into the -OH group. The response of PBE toward OPs was monitored using UV-vis absorption, fluorescence emission, IR spectroscopy, and mass spectrometry. Additionally, we have also explored the self-assembly of PBE in an organic-aqueous solvent mixture, which shows pure white light emission (WLE) with the CIE coordinates (0.33, 0.33) in a 50% dimethyl sulfoxide-water mixture. This work clearly reveals that PBE fluoroprobe can be employed for sensitive detection of hazardous OPs present in old ethereal solvents. Moreover, the ability of PBE to generate the perfect pure WLE makes it a potential candidate for application in organic light-emitting devices.

Metal Nanoparticles as Sustainable Tools for C-N Bond Formation via C-H Activation

The design of highly active metal nanoparticles to be employed as efficient heterogeneous catalysts is a key tool for the construction of complex organic molecules and the minimization of their environmental costs. The formation of novel C-N bonds via C-H activation is an effective atom-economical strategy to access high value materials in pharmaceuticals, polymers, and natural product production. In this contribution, the literature of the last ten years on the use of metal nanoparticles in the processes involving direct C-N bond formation will be discussed. Where possible, a discussion on the role and influence of the support used for the immobilization and/or the metal chosen is reported. Particular attention was given to the description of the experiments performed to elucidate the active mechanism.

Integrating CuO-Fe2 O3 Nanocomposites and Supramolecular Assemblies of Phenazine for Visible-Light Photoredox Catalysis

A photoredox catalytic ensemble consisting of CuO-Fe₂ O₃ nanocomposites and oligomeric derivative of phenazine has been developed. The prepared system acts as an efficient photoredox catalyst for C-N bond formation reaction via SET mechanism under 'green' conditions (aerial environment, mixed aqueous media, recyclable), requiring less equivalents of base and amine substrate. The present study demonstrates the significant role of supramolecular assemblies as photooxidants and reductants upon irradiation and their important contribution towards the activation of the metallic centre through energy transfer and electron transfer pathways. The potential of oligomer 4: CuO-Fe₂ O₃ has also been explored for C-C bond formation reactions via the Sonogashira protocol.

Modern Catalysts in A3- Coupling Reactions

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Propargylamines are an important constituent of diverse, biologically active and industrially valuable compounds. These useful, convenient and effective compounds can be synthesized via the A3-coupling reactions between an aldehyde, amine, and alkyne in the presence of a catalyst. In the past years, most of the catalysts containing transition metals were applied in these reactions, but today, various heterogeneous catalysts, especially nanocatalysts are used. The purpose of this review was to introduce some modern catalysts for the A3-coupling reaction.

σ-H-H, σ-C-H, and σ-Si-H Bond Activation Catalyzed by Metal Nanoparticles

Activation of H-H, Si-H, and C-H bonds through σ-bond coordination has grown in the past 30 years from a scientific curiosity to an important tool in the functionalization of hydrocarbons. Several mechanisms were discovered via which the initially σ-bonded substrate could be converted: oxidative addition, heterolytic cleavage, σ-bond metathesis, electrophilic attack, etc. The use of metal nanoparticles (NPs) in this area is a more recent development, but obviously nanoparticles offer a much richer basis than classical homogeneous and heterogeneous catalysts for tuning reactivity for such a demanding process as C-H functionalization. Here, we will review the surface chemistry of nanoparticles and catalytic reactions occurring in the liquid phase, catalyzed by either colloidal or supported metal NPs. We consider nanoparticles prepared in solution, which are stabilized and tuned by polymers, ligands, and supports. The question we have addressed concerns the differences and similarities between molecular complexes and metal NPs in their reactivity toward σ-bond activation and functionalization.

ZnCl2 loaded TiO2 nanomaterial: an efficient green catalyst to one-pot solvent-free synthesis of propargylamines

One-pot green synthesis of propargylamines using ZnCl₂ loaded TiO₂ nanomaterial under solvent-free conditions has been effectively accomplished. The aromatic aldehydes, amines, and phenylacetylene were reacted at 100 °C in the presence of the resultant catalyst to form propargylamines. The nanocrystalline TiO₂ was initially synthesized by a sol-gel method from titanium(iv) isopropoxide (TTIP) and further subjected to ZnCl₂ loading by a wet impregnation method. X-ray diffraction (XRD) patterns revealed the formation of crystalline anatase phase TiO₂. Field emission scanning electron microscopy (FESEM) showed the formation of agglomerated spheroid shaped particles having a size in the range of 25-45 nm. Transmission electron microscopy (TEM) validates cubical faceted and nanospheroid-like morphological features with clear faceted edges for the pure TiO₂ sample. Surface loading of ZnCl₂ on spheroid TiO₂ nanoparticles is evident in the case of the ZnCl₂ loaded TiO₂ sample. X-ray photoelectron spectroscopy (XPS) confirmed the presence of Ti⁴⁺ and Zn²⁺ species in the ZnCl₂ loaded TiO₂ catalyst. Energy-dispersive X-ray (EDS) spectroscopy also confirmed the existence of Ti, O, Zn and Cl elements in the nanostructured catalyst. 15% ZnCl₂ loaded TiO₂ afforded the highest 97% yield for 3-(1-morpholino-3-phenylprop-2-ynyl)phenol, 2-(1-morpholino-3-phenylprop-2-ynyl)phenol and 4-(1,3-diphenylprop-2-ynyl)morpholine under solvent-free and aerobic conditions. The proposed nanostructure-based heterogeneous catalytic reaction protocol is sustainable, environment-friendly and offers economic viability in terms of recyclability of the catalyst.

Superparamagnetic nanoparticle-catalyzed coupling of 2-amino pyridines/pyrimidines with trans-chalcones

An aerobic coupling of 2-aminopyrimidines or 2-aminopyridines with trans-chalcones to afford aroylimidazo[1,2-a]pyrimidines and aroylimidazo[1,2-a]pyridines is reported. Reactions proceed in the presence of CuFe₂O₄ superparamagnetic nanoparticle catalyst, two equivalents of iodine, oxygen oxidant, and 1,4-dioxane solvent. The catalyst is superior to many common copper or iron complexes. Copper ferrite could be easily separated by magnetic decantation and reused up to 5 times without a major loss of activity. The method described here marks a rare example of using a simple, heterogeneous catalyst for synthesis of fused heterocycles. To our best knowledge, aroylimidazo[1,2-a]pyrimidines and aroylimidazo[1,2-a]pyridines were not previously synthesized using this protocol.

An aerobic coupling of 2-aminopyrimidines or 2-aminopyridines with trans-chalcones to afford aroylimidazo[1,2-a]pyrimidines and aroylimidazo[1,2-a]pyridines is reported.

Development of a supramolecular ensemble of an AIEE active hexaphenylbenzene derivative and Ag@Cu2O core-shell NPs: an efficient photocatalytic system for C-H activation

A supramolecular ensemble having Ag@Cu2O core-shell nanoparticles stabilized by aggregates of a hexaphenylbenzene derivative has been developed which exhibits excellent photocatalytic efficiency in reactions involving preparation of imidazole and benzimidazole derivatives via C-H activation.

Synthesis of quinolines and naphthyridines via catalytic retro-aldol reaction of β-hydroxyketones with ortho-aminobenzaldehydes or nicotinaldehydes

A Cu(i)-catalyzed retro-aldol reaction of β-hydroxyketones with ortho-aminobenzaldehydes and nicotinaldehydes is reported that produces a range of quinolines and naphthyridines with high efficiency and selectivity. This reaction uses β-hydroxyketones as a regiospecific ketone-protected enolate source via copper-catalyzed retro-aldol C_α-C_β bond cleavage. The in situ generated copper enolate undergoes kinetically favorable cyclization with ortho-amino aryl aldehydes to produce quinolines and naphthyridines in a chemo- and regioselective manner. The mild and weakly basic reaction conditions also suppress possible side reactions of benzaldehydes under strongly basic conditions, resulting in improved reaction yields.

Post-synthetically modified MOF for the A3-coupling reaction of aldehyde, amine, and alkyne

A new heterogeneous NHC catalyst (Ag-NHC-MOF) was synthesized by the post-synthetic modification of an azolium-containing metal–organic framework.

Synthesis and Reactivity of Propargylamines in Organic Chemistry

Propargylamines are a versatile class of compounds which find broad application in many fields of chemistry. This review aims to describe the different strategies developed so far for the synthesis of propargylamines and their derivatives as well as to highlight their reactivity and use as building blocks in the synthesis of chemically relevant organic compounds. In the first part of the review, the different synthetic approaches to synthesize propargylamines, such as A³ couplings and C-H functionalization of alkynes, have been described and organized on the basis of the catalysts employed in the syntheses. Both racemic and enantioselective approaches have been reported. In the second part, an overview of the transformations of propargylamines into heterocyclic compounds such as pyrroles, pyridines, thiazoles, and oxazoles, as well as other relevant organic derivatives, is presented.

A novel environmentally sustainable synthesis of Au–Ag@AgCl nanocomposites and their application as an efficient and recyclable catalyst for quinoline synthesis

An eco-friendly synthesis of Au–Ag@AgCl NCs was described using the tuber extract of Nephrolepis cordifolia. The synthetic utility of the NCs was demonstrated by the synthesis of pharmaceutically important quinoline derivatives.

Magnetically recoverable graphene-based nanocomposite material as an efficient catalyst for the synthesis of propargylamines via A3 coupling reaction

The magnetically separable Au NPs–Fe₃O₄–rGO catalyst provides a robust and efficient route for the A³ coupling reaction of secondary amines, terminal alkynes and aldehyde with tolerance of diverse functional groups for the synthesis of propargylamine in high yields.

Novel routes to quinoline derivatives from N-propargylamines

A walk around the new avenue to the synthesis of quinoline derivatives from N-propargylamines.

Zn(ii) anchored onto the magnetic natural hydroxyapatite (ZnII/HAP/Fe3O4): as a novel, green and recyclable catalyst for A3-coupling reaction towards propargylamine synthesis under solvent-free conditions

In this paper, Zn(ii) anchored onto the magnetic natural hydroxyapatite (Zn^II/HAP/Fe₃O₄), as a new and magnetically recoverable catalyst, was prepared and characterized using different techniques such as FT-IR, XRD, TGA, TEM, EDX, VSM and ICP.

Cobalt-catalyzed synthesis of quinolines from the redox-neutral annulation of anilides and alkynes

A new method of cobalt-catalyzed annulation of anilides and internal alkynes for the efficient synthesis of quinoline scaffolds was developed.