ESP Promoted “On Water” Click Reaction: A Highly Economic and Sustainable Protocol for 1,4-Disubstituted-1H-1,2,3-Triazole Synthesis at Room Temperature

Synthesis of bioactive scaffolds catalyzed by agro-waste-based solvent medium

The backbone of synthetic organic chemistry is the formation of carbon–carbon and carbon–heteroatom bonds. Scientists are actively working to develop new methods of bond-forming reactions because it is one of the most useful tools for the development of structurally diverse molecular entities. On the other hand, scientists are constantly discovering chemical processes to make them more sustainable in order to avoid the ever-increasing chemical emission associated with hazards to the environment. Thus, the development of greener catalytic reactions demonstrated a massive uptick in the ability to carry out carbon–carbon and carbon–heteroatom bond-forming reactions under environmentally friendly and simple reaction conditions. Various approaches are demonstrated, namely, solvent-free, microwave irradiation, ionic liquids, ball milling, ultrasound, one-pot, and aqueous-mediated methods under green chemistry protocol. Agro-waste is the postharvest part or agricultural residues derived from various agricultural activities, which has diverse scope and applications. The use of this agro-waste is an eco-friendly and cost-effective process of waste management. Appropriate and optimal utilization of these waste by-products is one of the major challenges in the present days. The recent trend around the globe is to transform waste into wealth concepts to achieve various applications. Agro-waste-derived ashes and extracted medium are successfully studied recently as a heterogeneous- or homogenous-based catalyst in various organic transformations. Agro-waste-derived catalysts are easily available, cost-effective, simple to prepare, nontoxic, easy to handle, biodegradable, and more environmentally benign. This article focuses more on a few instances of agro-waste-based homogeneous and heterogeneous organic synthesis, especially those used in the construction of bioactive molecule synthesis via C–C and C–X bond formation reactions are discussed. The compiled literature in this article is based on keywords used in the search engine on “agro-waste-based catalyst for organic transformations”, and review articles published on this topic, future scope, and summary are discussed.

Advances in Triazole Synthesis from Copper-catalyzed Azide-alkyne Cycloadditions (CuAAC) Based on Eco-friendly Procedures

Background:

1,2,3-triazoles are an important class of organic compounds and because of their aromatic stability, they are not easily reduced, oxidized or hydrolyzed in acidic and basic environments. Moreover, 1,2,3-triazole derivatives are known by their important biological activities and have drawn considerable attention due to their variety of properties. The synthesis of this nucleus, based on the click chemistry concept, through the 1,3-dipolar addition reaction between azides and alkynes is a well-known procedure. This reaction has a wide range of applications, especially on the development of new drugs.

Methods:

The most prominent eco-friendly methods for the synthesis of triazoles under microwave irradiation published in articles from 2012-2018 were reviewed.

Results:

In this review, we cover some of the recent eco-friendly CuAAC procedures for the click synthesis of 1,2,3-triazoles with remarks to new and easily recoverable catalysts, such as rhizobial cyclic β-1,2 glucan; WEB (water extract of banana); biosourced cyclosophoraose (CyS); egg shell powder (ESP); cyclodextrin (β- CD); fish bone powder; nanoparticle-based catalyst, among others.

Conclusion:

These eco-friendly procedures are a useful tool for the synthesis of 1,2,3-triazoles, providing many advantages on the synthesis of this class, such as shorter reaction times, easier work-up and higher yields when compared to classical procedures. Moreover, these methodologies can be applied to the industrial synthesis of drugs and to other areas.

A Low-Cost, Well-Designed Catalytic System Derived from Household Waste "Egg Shell": Applications in Organic Transformations

A waste feedstock-derived economical basic alternative catalyst is described in this review. Eggshell is one of the household wastes created in tons of weight daily. Therefore, in order to reduce the environmental pollution-related problems, its use in heterogeneous catalysis can be attributed as a great contribution for the chemical and material science society to carry out several known reactions and for the much-needed energy alternative biodiesel production as low-cost catalytic system. Keeping green chemistry in mind, industrial use of these catalysts may also reduce the use of other traditionally used high-cost chemical catalytic systems.