Single and double A3-coupling (aldehyde-amine-alkyne) reaction catalyzed by an air stable copper(I)-phosphole complex

Metal-Catalysed A3 Coupling Methodologies: Classification and Visualisation

The multicomponent reaction of aldehydes, amines, and alkynes, known as A3 coupling, yields propargylamines, a valuable organic scaffold, and has received significant interest and attention in the last years. In order to fully realise the potential of the metal-based catalytic protocols that facilitate this transformation, we summarise substrates, in situ and well-characterised synthetic methods that provide this scaffold and attempt a monumental classification considering several variables (Metal, Coordinating atom(s), Ligand type and name, in-situ or well-characterised, co-catalyst, catalyst and ligand Loading (mol%), solvent, volume, atmosphere, temperature, microwave, time, yield, selectivity (e.e. d.r.), substrate name, functionality, loading (amines, aldehydes, alkynes), and use of molecular sieves). This pioneering work creates a valuable database that contains 2376 entries and allows us to produce graphs and better visualise their impact on the reaction.

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.

In Situ Immobilized Silver Nanoparticles on Rubia tinctorum Extract-Coated Ultrasmall Iron Oxide Nanoparticles: An Efficient Nanocatalyst with Magnetic Recyclability for Synthesis of Propargylamines by A3 Coupling Reaction

This research suggests a green method for synthesizing hybrid magnetic nanocomposites that can be used as a reductant and a stabilizing agent for immobilizing metal nanoparticles (NPs). The central idea is the modification of magnetic NPs using Rubia tinctorum extract, which consists of numerous carbonyl and phenolic hydroxyl functional groups to increase adsorption of metals and chelate silver ions, and decrease the adsorption of silver ions by Ag NPs, in situ. Thus, the suggested catalyst preparation process does not require toxic reagents, additional reductants, and intricate instruments. To show the effectiveness of the plant extract in reducing and immobilizing Ag NPs, the structural, morphological, and physicochemical features of the particles are studied using Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. One of the advantages of the suggested method is to reduce the size of the magnetic NPs from 15-20 to 2-5 nm, in the presence of the extract. Additionally, the prepared Fe3O4@R. tinctorum/Ag nanocatalyst is demonstrated to exhibit a very high activity in the catalysis of the three-component reaction of aldehydes, amines, and alkynes (A3 coupling) with good to high yields of diverse propargylamines. Moreover, the nanocatalyst can be recovered several times with no considerable leaching or loss of performance.

Immobilized Gold Nanoparticles Prepared from Gold(III)-Containing Ionic Liquids on Silica: Application to the Sustainable Synthesis of Propargylamines

A cycloaurated phosphinothioic amide gold(III) complex was supported on amorphous silica with the aid of an imidazolium ionic liquid (IL) physisorbed in the SiO₂ pores (SiO₂⁻IL) and covalently bonded to the SiO₂ (SiO₂@IL). Gold(0) nanoparticles (AuNPs) were formed in situ and subsequently immobilized on the SiO₂⁻IL/SiO₂@IL phase. The resulting catalytic systems Au⁻SiO₂⁻IL and Au⁻SiO₂@IL promoted the solvent-free A³ coupling reaction of alkynes, aldehydes, and amines in high yields under solvent-free conditions with very low catalyst loading and without the use of additives. The Au⁻SiO₂@IL catalyst showed good recyclability and could be reused at least five times with yields of propargylamines of ≥80%. This synthetic method provides a green and low cost way to effectively prepare propargylamines. Additionally, 31P high resolution magic angle spinning (HRMAS) NMR spectroscopy is introduced as a simple technique to establish the Au loading of the catalyst.

Green synthesis of Au nanoparticles using an aqueous extract ofStachys lavandulifoliaand their catalytic performance for alkyne/aldehyde/amine A3coupling reactions

High reaction rate and easy availability make green synthesis of metal nanoparticles noticeable.

Reaction of carbonyl trinuclear clusters with 2,5-bis(2-thienyl)-1-phenyl-phosphole as a ligand: a new pathway to ruthenacyclopentadiene and cyclopentadienone ruthenium complexes

A novel pathway for the formation of ruthenacyclopentadiene and cyclopentadienone ruthenium complexes is described.