Coupling reactions form an important class of reactions in organic synthesis and these reactions are usually catalysed by metals and are of great significance. Copper due to its versatility and low toxicity has always gained much attention. This first review on copper‐catalysed amination of aryl and heteroaryl halides summarises the developments in this area and covers literature upto 2019.

Nickel-catalyzed C–H activation has become a predominant and ubiquitous research area in organic chemistry.

Manganese‐catalysed reactions have attracted great attention recently due to the high relative abundance and cheap and eco‐friendly behaviour. Applications of manganese catalysis in cross‐dehydrogenative coupling are among the hottest areas since 90% of the contributions are very recent. Dehydrogenation of alcohols using Mn‐pincer systems is highly explored nowadays for cross‐coupling to synthesise a variety of products and Mn‐catalysed C−H activation, and radical reactions are applied in dehydrogenative couplings of various synthons. This review focuses on the synthesis of synthetically as well as biologically important motifs such as carbonyl compounds, olefins, nitrogen heterocycles, amines, imines, etc. using manganese‐catalysed dehydrogenative cross‐coupling reactions.

The asymmetricM annichr eactioni savery important method for CÀCb ond formation,a nd it is the classical method for the preparation of b-amino ketones and aldehydes. The resulting b-amino carbonyl compounds are widely found in nature, which attests to the importance of this reaction. This Focus Review providesa no verview of asymmetricM annich reactions, the various catalysts that have been used, and its applications,f or papers published since 2013. Scheme1.The Mannich reaction.Scheme2.The mechanism of the Mannich reaction;reproduced with permissionfrom Ref.[1]. andhi University. His research interests are in the areaso fo rganic synthesis, medicinal chemistry,a nd catalysis, in particularr uthenium-, iron-, zinc-, and copper-catalyzedr eactions. His h-index is 24.

Among the various metal catalysts, zinc salts have enormous potential due to their availability, low toxicity, eco‐friendliness and inexpensive nature. Biologically zinc is an essential element in our daily lives and it possesses a wide range of applications in pharmaceutical as well as material sciences. In synthetic organic chemistry, the main role of zinc salts is as a Lewis acid catalyst. The importance of the synthesis of heterocycles is attested by the vast number of applications of these compounds in the chemical and pharmaceutical industries. The environmentally benign nature of zinc, its abundance and the Lewis acid character of most of its compounds make it a suitable catalyst for heterocycle synthesis. This is the first review exclusively on zinc‐catalyzed heterocycle synthesis and deals with the recent applications, especially using tandem/domino or one‐pot reaction strategies and covers the literature from 2008 to 2018.

Microwave (MW) assisted multicomponent reactions (MCRs) provide facile and expeditious procedures for the synthesis of several diversely functionalised molecules. Significant enhancement in selectivity, purity and reproducibility is offered by this process. Shorter reaction times as well as higher product yield are attained efficiently using MW assisted MCRs. The present review focuses on the developments in this field covering literature from 2013–2019 and the topic is categorised based on the final products obtained.

This first review on this topic focuses on the developments in the chemistry of Pd-catalyzed multi-component reactions (MCRs).

Heterocycles are generally biologically active compoundsa nd find widespread applications in medicinalc hemistry,a gricultural science and the fine chemical industry.F or the synthesis and functionalization of heterocycles,g reat efforts have been ascribed over the past decades.T he syntheses of heterocyclic compounds are significant due to their diverse biological activity.R ecently,i ron-catalyzed reactions have experienced remarkable progress in the synthesiso fh eterocycles.T hisr eview summarizes recent trends in the iron-catalyzed synthesiso fn itrogen-containingheterocyclic compounds.1I ntroduction