Recent advances in the application of magnetic bio-polymers as catalysts in multicomponent reactions.

Magnetic nanoparticles have attracted significant attention due to their high surface area and superparamagnetic properties. Bio-polymers composed of polysaccharides including alginate, cellulose, glucose, dextrin, chitosan, and starch can be immobilized on magnetic nanoparticles. Bio-polymers can be obtained from natural sources, such as plants, tunicates, algae, and bacteria. Bio-polymers obtained from natural sources have attracted attention due to their various properties including efficient functional groups, non-toxicity, low cost, availability, and biocompatibility. According to the targets of "green chemistry", the application of bio-polymers is effective in reducing pollution. Furthermore, they are excellent agents for the functionalization of magnetic nanoparticles to yield nanomagnetic bio-polymers, which can be applied as recoverable and eco-friendly catalysts in multicomponent reactions.

Magnetically recoverable catalysts for the preparation of pyridine derivatives: an overview.

Magnetically recoverable nano-catalysts can be readily separated from the reaction medium using an external magnet. In recent years, chemistry researchers have employed them as catalysts in chemical reactions. The high surface area, simple preparation, and modification are among their major advantages. Pyridine derivatives are an important category of heterocyclic compounds, which show a wide range of excellent biological activities, including IKK-ß inhibitors, anti-microbial agents, A2A adenosine receptor antagonists, inhibitors of HIV-1 integrase, anti-tumor, anti-inflammatory, and anti-Parkinsonism. Recently, the catalytic activity of magnetic nanoparticles was investigated in multicomponent reactions in the synthesis of pyridine derivatives, which is discussed in this review.

Recent Progress Towards Synthesis of the Indolizidine Alkaloid 195B.

BACKGROUND: Natural products have been received attention due to their importance in human life as those are biologically active. In this review, there are some reports through different methods related to the synthesis of the indolizidine 195B which was extracted from poisonous frog; however, due to respect nature, the synthesis of natural compounds such as indolizidine has been attracted much attention among scientists and researchers. OBJECTIVE: This review discloses the procedures and methods to provide indolizidine 195B from 1989 to 2018 due to their importance as a natural product. CONCLUSION: There are several methods to give rise to the indolizidine 195B as a natural product that is highly active from the biological perspective in pharmaceutical chemistry. In summary, many protocols for the preparations of indolizidine 195B from various substrates, several reagents, and conditions have been reported from different aromatic and aliphatic.

Ultrasound-assisted synthesis of heterocyclic compounds.

In this review, we tried to underscore the synthesis of the heterocyclic compounds under assisted ultrasonic irradiation. The ultrasonic irradiation has been applied for medicinal chemistry and drug discovery process since it dramatically reduces reaction times, from days or hours to minutes. Also, ultrasonic irradiation provides lower cost, excellent yields, greater purity, and simple workups as compared to lower yields, longer reaction times, lesser purity and in the conventional methods. In this review, we have compared synthesis of the heterocyclic compounds under ultrasonic irradiation with other methods.