Metal Nanoparticles: An Efficient Tool for Heterocycles Synthesis and Their Functionalization via C-H Activation
01 May 2019-Vol. 6, Iss: 2, pp 79-91
TL;DR: In this article, a review of metal nanoparticles as effective catalysts for the synthesis and functionalization of heterocycles via C-H activation is presented, highlighting the need for future development and research in this area and guiding researchers towards fulfilling that goal.
Abstract:
Metal nanoparticles have been extensively used in the synthesis of organic
molecules during the last few decades especially due to their high catalytic activity. Organic reactions
involving C-H functionalisations are very much in demand as they provide a direct method of
derivatisation of organic molecules, thus making the process economical. In the recent years, metal
nanoparticles catalysed C-H activation reactions have led to the design of useful molecules especially
heterocyclic motifs which form the core structure of drugs and thus have high biological and industrial
importance.
In this review, we present a collection of reactions where metal nanoparticles are instrumental
in the synthesis and functionalization of heterocycles via C-H activation. The review consists
of three units namely, Nano-copper catalysed C-H activation reactions, nano-palladium catalysed CH
activation reactions and other nano-metals catalysed C-H activation reactions.
The discussion reflects the scope of nano-metals as effective catalysts for the synthesis and
functionalization of heterocycles as well as the efficiency of nano-metals towards catalysing economic
and environmentally viable reaction protocols.
The theme of this review is to correlate nanometal catalysis, heterocyclic synthesis and
C-H activation, each of which in itself forms an integral part of modern day chemical research. Thus,
the review will hopefully highlight the need for future development and research in this area and be
instrumental in guiding researchers towards fulfilling that goal.
Citations
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TL;DR: In this paper, a complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019 was made, and the focus 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, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the
Abstract: 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.
37 citations
01 Jun 2020
TL;DR: An efficient protocol by Rh-catalyzed direct C-H vinylation of 2-arylpyridines with a commercially available and air-stable potassium vinyl donor has been developed as discussed by the authors.
Abstract: An efficient protocol by Rh-catalyzed direct C–H vinylation of 2-arylpyridines with a commercially available and air-stable potassium vinyl donor has been developed. This method affords the corresponding pyridinyl styrene derivative with moderate to excellent yields under mild conditions, which is extremely beneficial to the total synthesis of the natural product palmatine.
6 citations
TL;DR: In this paper , the design and preparation of highly active metal nanoparticles as efficient catalysts for C-H bond activation under mild reaction conditions still continue to be investigated, and a review focuses on the functionalization of unactivated C(sp3)−H, c(sp2)-H, and c-sp−H bonds exploiting metal and metal oxide nanoparticles C−O and C−X (X = Halogen, B, P, S, Se) bond formation.
Abstract: The direct functionalization of an inactivated C–H bond has become an attractive approach to evolve toward step-economy, atom-efficient and environmentally sustainable processes. In this regard, the design and preparation of highly active metal nanoparticles as efficient catalysts for C–H bond activation under mild reaction conditions still continue to be investigated. This review focuses on the functionalization of un-activated C(sp3)–H, C(sp2)–H and C(sp)–H bonds exploiting metal and metal oxide nanoparticles C–H activation for C–O and C–X (X = Halogen, B, P, S, Se) bond formation, resulting in more sustainable access to industrial production.
References
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TL;DR: The development of green, sustainable and economical chemical processes is one of the major challenges in chemistry as discussed by the authors, and the need for efficient and selective catalytic reactions that will transform raw materials into valuable chemicals, pharmaceuticals and fuels, green chemistry also strives for waste reduction, atomic efficiency and high rates of catalyst recovery.
Abstract: The development of green, sustainable and economical chemical processes is one of the major challenges in chemistry. Besides the traditional need for efficient and selective catalytic reactions that will transform raw materials into valuable chemicals, pharmaceuticals and fuels, green chemistry also strives for waste reduction, atomic efficiency and high rates of catalyst recovery.Nanostructured materials are attractive candidates as heterogeneous catalysts for various organic transformations, especially because they meet the goals of green chemistry. Researchers have made significant advances in the synthesis of well-defined nanostructured materials in recent years. Among these are novel approaches that have permitted the rational design and synthesis of highly active and selective nanostructured catalysts by controlling the structure and composition of the active nanoparticles (NPs) and by manipulating the interaction between the catalytically active NP species and their support. The ease of isolation a...
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TL;DR: Ni-based catalytic systems for the arylation of heteroarenes with aryl halides and triflates have been established and a rapid synthesis of febuxostat, a drug for gout and hyperuricemia, is demonstrated.
269 citations
TL;DR: Pd@PPy hybrid catalytic materials are synthesized in water via redox polymerization reaction of pyrrole with [Pd(NH 3 ) 4 Cl 2 ]. The nanocomposites formed are composed of highly dispersed palladium particles which are either zerovalent or easily reducible as discussed by the authors.
Abstract: Pd@PPy hybrid catalytic materials are synthesized in water via redox polymerization reaction of pyrrole with [Pd(NH 3 ) 4 Cl 2 ]. The nanocomposites formed are composed of highly dispersed palladium particles which are either zerovalent or easily reducible, and are embedded in spherical polypyrrole globules. A unique combination of high palladium dispersion (NP size: 2.4 nm) and elevated palladium content (35 wt%) is obtained. The components of these novel nanocomposites are characterized by means of FTIR, XPS, XRD, SEM, and TEM microscopy techniques. The process of formation in solution is also monitored using UV-visible and DLS techniques. The application of these novel hybrid nanomaterials in the palladium-catalyzed direct arylation of heteroaromatics is reported. High effi ciency in C–C bond formation is obtained using these materials. Furans and thiophenes are arylated by using bromoarenes. Pd@PPy nanocomposites can effi ciently couple n -butyl furan and n -butyl thiophene with bromobenzene and bromoquinoline, as well as with activated or deactivated electron-poor and electron-rich functionalized bromoarenes. Thus, a clean reaction process is developed that combines the absence of organic ligand in catalytic reactions and easy recovery of Pd@PPy nanocomposite via simple fi ltration. Preliminary kinetic and post-catalysis studies suggest a molecular or colloidal soluble active species. These very active species are effi ciently delivered by the nanocomposites and susceptible to a surprisingly uniform back redeposition within the polypyrrole support.
120 citations
TL;DR: Palladium catalyzed coupling reactions have emerged as a versatile, convenient, selective and mild protocol that can usually be adapted in any synthetic scheme for important target molecules with various degrees of structural complexity as discussed by the authors.
Abstract: Palladium catalyzed coupling reactions have emerged as a versatile, convenient, selective and mild protocol that can usually be adapted in any synthetic scheme for important target molecules with various degrees of structural complexity. While anchored catalysts offer recycling advantages, palladium nanoparticles display an impressive ability to catalyse coupling reactions. Along with their successful applications in organic synthesis, controversy has also arisen concerning the exact nature – heterogeneous or homogeneous – of the reaction catalyzed by palladium nanoparticles.
113 citations