Montmorillonite-catalysed coupling reactions: a green overview

Coupling reactions are widely significant in organic synthesis, and within the green chemistry perspective the utilization of montmorillonite clay as a catalyst offers a viable alternative to traditional coupling protocols. Montmorillonite clay is an effective, eco-friendly, economic and recyclable catalyst, and its heterogeneous nature facilitates easy isolation and reusability. The majority of coupling reactions executed with montmorillonite catalysts offer notable advantages over their homogeneous counterparts, including enhanced efficiency, selectivity, operational simplicity, elimination of toxic solvents and ligands, maintenance of mild reaction conditions, and cost-effectiveness. This review gives a comprehensive summary of the literature to date on coupling reactions catalysed by montmorillonite clay, while also outlining future prospects in this area.

Palladium N-Heterocyclic Carbene-Catalyzed Aminations: An Outline

Amination reactions play a pivotal role in synthetic organic chemistry, facilitating the generation of nitrogen-containing scaffolds with broad applications in drug synthesis, material production, polymer formation, and the generation of amino acids and peptides. Amination offers the potential to fine tune the properties of natural products and produce functional materials for various applications. Palladium N-heterocyclic carbene (Pd-NHC) emerges as an innovative and highly effective catalyst in this context. Under favorable reaction conditions, this robust and simple catalyst efficiently facilitates the synthesis of a diverse range of compounds with varying complexity and utility. Pd-NHC complexes exhibit significant σ-electron donating potential, enhancing the ease of the oxidative addition process in their mechanistic pathway. Their steric topography further contributes to a rapid reductive elimination. These complexes demonstrate remarkable stability, a result of the strong Pd-ligand bond. The wide variety of Pd-NHC complexes has proven highly efficient in catalyzing reactions across a spectrum of complexities, from simple to intricate. The domain of aminations catalyzed by Pd-NHC has undergone significant diversification, presenting new opportunities, particularly in the realms of material chemistry and natural product synthesis. This review outlines the advancements in Pd-NHC-catalyzed amination reactions, covering literature up to date.

Silver-catalyzed synthesis of nitrogen heterocycles: recent advancements

Heterocyclic chemistry is an ever-expanding field without boundaries. Heterocycles play a significant role in medicinal and pharmaceutical chemistry, the agricultural industry and materials science. Among heterocycles, N-heterocycles constitute a large family. Their ubiquity in living and non-living systems makes them an endless topic for research. Being a part of the research community, we need to balance environmental concerns with scientific and economic development. So, research that is coherent with nature is a trending domain at all times. Silver catalysis possesses a greener face in organic synthesis. The simple, rich and extensive chemistry shown by silver makes it an attractive choice for catalysis. Inspired by its versatility and uniqueness we have compiled here recent developments in the silver-catalyzed synthesis of nitrogen-containing heterocycles since 2019. The high efficiency, regioselectivity, chemoselectivity, recyclability of the catalytic system, greater atom economy and simple reaction setup are the major highlights of this protocol. It is a hot research topic which is evident from the large number of works carried out for the fabrication of a range of N-heterocycles with varying complexities.

An overview of Ruthenium-catalyzed multicomponent reactions

Abstract:

In multicomponent reactions (MCRs), highly functionalized compounds can be formed through the reaction between three or more reactants in a one-pot manner. These reactions provide products through the utilization of a lesser amounts of energy, time, and effort. MCRs also possess advantages like the generation of lesser waste materials, fewer resources are needed, high convergence etc. In terms of energy economy and atom economy, MCRs are superior to multistep synthesis. A wide range of products can be acquired by combining the reagents in a variety of ways and thus MCRs became popular in various fields such as catalysis, pharmaceutical chemistry, material science, agrochemistry, fine chemistry and so on. MCRs obey the principles of green chemistry because these approaches are simple and eco-friendly. MCR is established as an unrivalled synthetic technique and is used by chemists at an accelerating rate in recent years. Ruthenium catalysts are cheap in comparison to palladium and rhodium, and generally show high activity. Ru possesses wide-ranging oxidation states due to its 4d75s1 electronic configuration. Numerous organic reactions are catalyzed by ruthenium and they are utilized in the formation of a wide range of pharmaceuticals and natural products, with biological importance. Minimum amounts of waste materials are formed in most of the ruthenium-catalyzed reactions and hence ruthenium catalysis pave way to environmentally benign protocols. Ruthenium chemistry has had a really big impact on organic synthesis in recent years that it is now on par with palladium in terms of relevance. The developments in the field of ruthenium-catalyzed multicomponent reactions are highlighted in this review, covering the literature up to 2021.

Transition metal-catalyzed synthesis of spirooxindoles

Spirooxindole is a principal bioactive agent and is observed in several natural products including alkaloids. They are broadly studied in the pharmaceutical field and have a significant role in the evolution of drugs such as anti-viral, anti-cancer, anti-microbial etc. In organic chemistry, an indispensable role is presented by transition metal catalysts. An effective synthetic perspective to spirooxindoles is the use of transition metals as the catalyst. This review discusses the synthesis of spirooxindoles catalyzed by transition metals and covers literature up to 2020.

Recent advances and perspectives in manganese-catalyzed C–H activation

Manganese-catalyzed C–H activation has become an emerging area in organic chemistry. These efficient and eco-friendly manganese catalysed reactions provides new opportunities in the field of synthetic organic chemistry.

Recent developments and perspectives in the copper-catalyzed multicomponent synthesis of heterocycles

Heterocyclic compounds have become an inevitable part of organic chemistry due to their ubiquitous presence in bioactive compounds. Copper-catalyzed multicomponent synthesis of heterocycles has developed as the most convenient and facile synthetic route towards complex heterocyclic motifs. In this review, we discuss the advancements in the field of copper-catalyzed multicomponent reactions for the preparation of heterocycles since 2018.

Heterocycles are abundant in several pharmaceutical and naturally occurring compounds. Copper-catalyzed multicomponent reactions are a convenient method for easy access to heterocycles. In this review, we focus on the advancement in this field for the past two years.

Recent Advances in the Synthesis of Pyrazole Derivatives

Pyrazole and its derivatives have gained wide attention in pharmaceutical, agrochemical and biological fields as well as in industry. They exhibit various biological activities such as anti-pyretic, anti-microbial, anti- inflammatory, anti-tumor, anti-viral, anti-histaminic, anti-convulsant, fungicidal, insecticidal, etc. In this review, we summarise the recent advances in the synthesis of pyrazole derivatives using various methodologies and covers literature from 2017-2020.

Progress and prospects in copper-catalyzed C-H functionalization

Copper-catalyzed C-H functionalization is becoming a significant area in organic chemistry. Copper is now widely used as a catalyst in organic synthesis as it is inexpensive and not very toxic. Functionalization of C-H bonds to construct wide varieties of organic compounds has received much attention in recent times. This review focuses on the recent advances in Cu-catalyzed C-H functionalization and covers literature from 2018-2020.

Recent advances and prospects in the palladium-catalyzed cyanation of aryl halides

Aryl nitriles are compounds with wide significance. They have made their own space in various sectors including pharmaceuticals, industries, natural product chemistry, and so on. Furthermore, they are also key intermediates in various transformations in organic chemistry. Transition metal-catalyzed cyanation reactions have proved to be a better replacement for the existing traditional synthetic strategies for aryl nitriles. Palladium is one of the most studied transition metals other than copper and nickel owing to its wide functional group compatibility and catalytic efficacy. There have been drastic developments in the field of palladium-catalyzed cyanation since its discovery in the 1973. This review summarizes the recent developments in the palladium-catalyzed cyanation of aryl halides and covers literature from 2012-2020.

Recent trends and applications of the Cadiot–Chodkiewicz reaction

The Cadiot–Chodkiewicz reaction offers an elegant strategy for the formation of 1,3-diynes via Cu-catalyzed cross-coupling of alkynyl halides with terminal alkynes in the presence of an amine.