A coupling is one of the few transition-metal catalyzed carbon-carbon bond forming reactions that have been established as a most direct, efficient and atom-economical synthetic approach to afford propargylamine derivatives using various catalysts. A large number of nanosized heterogeneous catalysts for three-component coupling reactions between an aldehyde, an amine, and a terminal alkyne have been popularly introduced as an A coupling in the last decade. The coupling product has found a broad application as a key intermediate for a variety of heterocyclic useful compounds and numerous biologically active molecules such as β-lactams, conformationally restricted peptides, isosteres, herbicides, fungicides, indolizines, pyrroles, quinolines and therapeutic drug molecules. This review aims to give an overview of the current progress made towards the preparation and application of various nanocatalysts-catalyzed A coupling transformations for the synthesis of propargylamines from 2007 to 2017. Several nanocatalysts based on metal and metal oxide nanoparticles (NPs) such as copper, gold, silver, iron, nickel, cobalt and zinc have successfully been employed in A coupling reactions. Besides, core-shells NPs, polymers, complexes, graphenes, metal-organic frameworks and ionic liquids have also been used in these reactions. Abundant examples have been given in this area. Different aspects of the reactions, disparate methods of preparation of nanocatalysts, characterization and their reusability have been perused.

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Copper nanoparticles (NPs) are one of the most commercialized nanomaterials. From the standpoint of nanotechnology copper-based nanostructured materials have many applications in biological process, folk medicine, electronics, and industrial fields. With growing concern regarding the energy crisis and problems of chemical and physical procedures to prepare the metal nanoparticles, efforts for alternative traditional chemistry attracted particular considerations. A widespread of researches have studied on biological methods which do not generate hazardous waste and therefore, don't need the purification processes. Plants could be remarkably valuable to exploring the biogenic synthesis of metal nanoparticles. The aim of this review is to provide further insight in to connections between plant extracts and synthesis of copper NPs. The utilization of living plants for biosynthesis of metal nanoparticles (MNPs) is a cost-effective and eco-friendly procedure. To date, the obtained results demonstrated several aspects of the plant physiology and their relations to nanoparticle synthesis. This work describes the state of the art and future challenges in green synthesis of copper NPs. This review has proven recent elevation in the green synthesis of Cu NPs, CuO NPs, Cu O NPs, CuS NPs, CuAl O and immobilized copper nanoparticles on the numerous supports such as Natrolite, bentonite, perlite, ZnO, MgO, MnO , reduced graphene oxide (RGO), and Fe O by a wide range of plant extracts. Therefore, detailed description of green synthesis and stabilizing agents concerning copper nanoparticles using these green sources is presented. Also, the catalytic activities of synthesized Cu-based recyclable nanocatalysts using various plant extracts in several chemical reactions such as oxidation, reduction, hydration, cyanation, cycloaddition, and coupling reactions were consciously investigated.

In this work, for the first time, Solanum melongena plant extract was used for the green synthesis of Pd/MnO 2 nanocomposite via reduction osf Pd(II) ions to Pd(0) and their immobilization on the surface of manganese dioxide (MnO 2 ) nanoparticles (NPs) as an effective support. The synthesized nanocomposite were characterized by various analytical techniques such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and UV-Vis spectroscopy. The catalytic activity of Pd/MnO 2 nanocomposite was used as a heterogeneous catalyst for the one-pot synthesis of 5-substituted 1H-tetrazoles from aryl halides containing various electron-donating or electron-withdrawing groups in the presence of K 4 [Fe (CN) 6 ] as non-toxic cyanide source and sodium azide. The products were obtained in good yields via a simple methodology and easy work-up. The nanocatalyst can be recycled and reused several times with no remarkable loss of activity. Highlights:• Green synthesis of Pd/MnO 2 nanocomposite using Solanum melongena extract.• Pd/MnO 2 nanocomposite was characterized by FT-IR, XRD, FESEM, EDS and TEM.• One-pot synthesis of 5-substituted 1H-tetrazoles from aryl halides using Pd/MnO 2 nanocomposite.• The catalyst can be easily recycled and reused several times without sensible loss in its catalytic efficiency.

A simple procedure for the palladium-catalyzed cyanation of aryl halides is described via a nucleophilic non-toxic cyanide source, K4[Fe(CN)6] in the presence of Pd/coral reef nanocomposite as a heterogeneous catalyst; the protocol provides a useful and easy method for the synthesis of aryl nitriles that are generated from the corresponding variant aryl halides, with sodium carbonate as a base. The nanocatalyst was prepared by a biological process using aqueous extract of leaves of Cucurbita pepo as a stabilizing and reducing agent and coral reef as a natural support, without deploying any hazardous chemicals. The catalyst, that is easily separable from the reaction mixture and reused multiple times, was characterized by FT-IR (Fourier-Transform Infrared Spectroscopy), ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy), XRD (X-ray Diffraction), TEM (Transmission Electron Microscopy), FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy Dispersive X-ray Spectroscopy) and elemental mapping.