Current Organic Chemistry - Volume 27, Issue 3, 2023

In organic synthesis, mechanochemical approaches have received increased attention because of their broad applications in green methodologies. By utilization of mechanical forces on the various reactants, there is a certain increase of their surface area and also areas of contact, which usually make reaction pathways more available through a greater number of effective collisions. Mechanical energy can be produced and transferred through ball mills, one of the highest necessary devices for green organic solid-state reactions. In the last few decades, various challenging organic transformations have been published using ball milling in different fields of organic synthesis. Ball milling has received tremendous attention in numerous organic synthesis since it allows for reactions to occur at ambient temperature in the absence of any solvent under mild conditions which are compatible for a green process. The carbon-carbon and carbon–heteroatom bond formation reactions and also synthesis of heterocyclic compounds are of ample importance in both academia and pharmaceutical industry. This review will highlight the recent developments of amidation reactions, asymmetric synthesis, various heterocyclic compounds synthesis, crosscoupling reactions, C–H bond activation for C–C and carbon–heteroatom bond formation reactions under the ballmilling conditions.

The literature survey reveals the applications of visible light as a sustainable energy source in the various constructive organic transformations by using homogeneous and heterogeneous photocatalysts, catalysts under suitable solvents, or under solvent-free conditions to attain green and sustainable chemistry. Recently, the crises of energy sources demand a sustainable and renewable energy source worldwide. In these circumstances, visible lightdriven organic transformations attracted much attention as a good alternative energy source. Due to the visible-light-driven organic synthesis offers several advantages such as natural abundance in the solar spectrum, friendly to the equipment, fewer side reactions, costfriendly, selective product formation, higher isolated yields of products, environmental friendliness and sustainability. On the other hand, the developments in chemistry are adopting the green culture, in this state of affairs, visible light will be a great substitute for non-renewable energy sources for chemical transformations and synthesis. It will reduce the consumption of fossil fuels which will lead the world toward achieving the goals of sustainable development. A number of different organic molecules are synthesized using different homogeneous and heterogeneous photocatalysts under visible light via different methods such as one-pot multi-component protocol, multi-step method, coupling and condensation method, etc. In this review paper, we have highlighted the basics and history of photochemical organic transformations using suitable photo-catalysts and dye-sensitized photochemical reactions. We have presented details of organic transformations under visible light using MOF, nano-material, COF, metal, graphitic carbon, organocatalyst as photocatalysts. We have also highlighted organic transformations using visible light in the absence of any metal or other catalysts. Thus, this review covers wide range of organic reactions under visible light and will benefit the synthetic organic chemist community.

The synthesis of organofluorine compounds plays a vital role in the field of pharmaceuticals, agrochemicals, and materials since the fluorine-containing compounds have shown improved biological and physicochemical properties. Significant research has been directed towards synthesizing organofluorine compounds because organofluorine compounds have been displayed in several biological activities, including anticancer, antitumor, antihypertensive, antidepressant, anti-HIV and treatment of stroke. Due to several pharmaceutical applications of organofluorine compounds, numerous conventional as well as green synthetic methodologies have been developed for the synthesis of fluorine-containing compounds. However, particularly, the synthesis of organofluorine compounds using green approaches has been continuously attracting research interest since green approaches have several advantages, including the use of inexpensive and nontoxic reagents, catalytic, highly efficient, short reaction time, energy efficient, high reaction yields, and environmentally benign over the conventional methods. Among the green tools, the use of microwave-assisted synthesis, water, and ionic liquids as green solvent/reaction media, organocatalysts, photocatalysts, and solvent-free and catalyst-free reaction conditions have been exploited in the past decades for the synthesis of organofluorine compounds. In this review, we highlighted the recent developments in various green methods for the synthesis of organofluorine compounds via electrophilic fluorination for synthesis of various fluorohydrins, fluorinated acyclic & cyclic β -ketoesters, 1,3-dicarbonyl compounds, cyclic and acyclic ketones, α - cyanoesters, α-aryl-tetralones, α-amino acids, flavanones, and several fluorinated heterocycles such as fluorinated pyridine, pyrimidine, pyrrole, pyrazolone, benzofuran, indole, flavanone, and coumarin derivatives. In addition, some green methodologies have been highlighted for the synthesis of biologically active fluorinated compounds, including HIV-1 integrase inhibitors, 20-deoxy-20-fluorocamptothecin, fluorinated estrone, sclareolide, BMS- 204352 (MaxiPost), fluorinated naproxen and fluoxetine.

The fused Nitrogen heterocyclic compounds and their derivatives have grown in prominence over the past several decades as a result of their significant medical value. The adaptable and easily synthesized N-Heterocyclic scaffolds are particularly exciting in both synthetic organic chemistry and the biological sector due to their powerful pharmacological properties, which are taken into consideration while considering their numerous uses. For the synthesis of N-heterocycles and their derivatives, several attempts were undertaken to create a variety of synthetic protocols. The N-Heterocyclic compounds provide a variety of adaptable structures for specific biological applications and represent novel, broad-spectrum antibacterial and anticancer agents. They typically have minimal toxicity profiles. The majority of these N-Heterocycles have demonstrated more cytotoxicity than the effective anticancer medication cisplatin. The design, synthesis, structural characterisation, and biological uses of N-Heterocycles are reviewed in this work. In this article, the developments made in this specific field are comprehensively examined.

The remarkable improvements in organic synthesis facilitated by zirconium dioxide- based nanoparticles are updated and summarized in this review. The ZrO2 acts as a versatile heterogeneous nanocatalyst and is used in various elementary organic reactions and many multicomponent reactions. The employment of these catalysts in organic synthesis leading to bio-active scaffolds provides the opportunity to carry out the reactions using facile synthetic protocol under mild environments that furnish the equivalent products in high yields and shorter reaction times. According to reports in the literature, ZrO2-based catalysts were removed from the reaction mixture and recycled many times.