Ultrasound assisted multicomponent reactions: A green method for the synthesis of N-substituted 1,8-dioxo-decahydroacridines using β-cyclodextrin as a supramolecular reusable catalyst in water

Sonochemical Protocols for Heterocyclic Synthesis: A Representative Review

In the present era of the industrial revolution, we all are familiar with ever-increasing environmental pollution released from various chemical processes. Chemical production has had a severe impact on the environment and human health. For the betterment of our environment, the chemical community has turned their interest to developing green, harmless and sustainable synthetic processes. To accomplish these goals of green chemistry, the extraordinary properties of sonication play an important role. It is well known that sonochemistry can make decisive contributions to creating high pressures of almost 1000 atm and very high temperatures in the range of 4500-5000 °C. The implementation of ultrasound in chemical transformations somehow fulfils the measures of green chemistry, as it reduces energy consumption, enhances product selectivity, and uses lesser amounts of hazardous chemicals and solvents. Furthermore, heterocyclic synthesis under ultrasonication offers several environmental and process-related advantages compared with conventional methods. The remarkable contribution of ultrasonics to the development of green and sustainable synthetic routes inspired us to write this article. Herein, we have discussed only some of the various synthetic methodologies developed for the construction of heterocyclic cores under ultrasonic irradiation, accompanied by mechanistic insights. In some cases, a comparison between sonochemical conditions and conventional conditions has also been investigated. We emphasized principally 'up to date' developments on various sono-accelerated chemical transformations comprising aza-Michael, aldol reactions, C-C couplings, oxidation, cycloadditions, multi-component reactions, etc. for the synthesis of heterocycles.

Greener organic synthetic methods: Sonochemistry and heterogeneous catalysis promoted multicomponent reactions

Ultrasound is an essential technique to improve organic synthesis from the point of view of green chemistry, as it can promote better yields and selectivities, in addition to shorter reaction times when compared to the conventional methods. Heterogeneous catalysis is another pillar of sustainable chemistry being the recycling and reuse of the catalysts one of its great advantage. In the other hand, multicomponent reactions provide the synthesis of structurally diverse compounds, in a one-pot fashion, without isolation and purification of intermediates. Thus, the combination of these protocols has proved to be a powerful tool to obtain biologically active organic compounds with lower costs, time and energy consumption. Herein, we provide a comprehensive overview of advances on methods of organic synthesis that have been reported over the past ten years with focus on ultrasound-assisted multicomponent reactions under heterogeneous catalysis. In particular, we present pharmacologically important N- and O-heterocyclic compounds, considering their synthetic methods using green solvents, and catalyst recycling.

N-Propyl benzoguanamine sulfonic acid supported on magnetic Fe3O4 nanoparticles: a novel and efficient magnetically heterogeneous catalyst for the synthesis of 1,8-dioxo-decahydroacridine derivatives

An MNPs-N-propyl-benzoguanamine-SO₃H nanocatalyst as a novel, retrievable, economic and heterogeneous catalyst is prepared for the synthesis of 1,8-dioxo-decahydroacridine derivatives.

Recent developments on ultrasound-assisted one-pot multicomponent synthesis of biologically relevant heterocycles

Heterocycles are the backbone of organic compounds. Specially, N- &O-containing heterocycles represent privileged structural subunits well distributed in naturally occurring compounds with immense biological activities. Multicomponent reactions (MCRs) are becoming valuable tool for synthesizing structurally diverse molecular entities. On the other hand, the last decade has seen a tremendous outburst in modifying chemical processes to make them sustainable for the betterment of our environment. The application of ultrasound in organic synthesis is fulfilling some of the goals of 'green and sustainable chemistry' as it has some advantages over the traditional thermal methods in terms of reaction rates, yields, purity of the products, product selectivity, etc. Therefore the synthesis of biologically relevant heterocycles using one-pot multi-component technique coupled with the application of ultrasound is one of the thrusting areas in the 21st Century among the organic chemists. The present review deals with the "up to date" developments on ultrasound assisted one-pot multi-component synthesis of biologically relevant heterocycles reported so far.