Mini-Reviews in Organic Chemistry - Volume 19, Issue 5, 2022

Background: Many pyrano[2,3-c]pyrazole derivatives display diverse biological activities and some of them are known as anticancer, analgesic, anticonvulsant, antimicrobial, antiinflammatory, and anti-malarial agents. In recent years, easy convergent, multicomponent reactions (MCRs) have been adopted to make highly functionalizedpyrano[2,3-c]pyrazole derivatives of biological interest. The synthesis of 1,4-dihydropyrano[2,3-c]pyrazole (1,4-DHPP, 2), 2,4- dihydropyrano[2,3-c]pyrazole (2,4-DHPP, 3), 4-hydroxypyrano[2,3-c]pyrazole (4-HPP, 4) derivatives, 1,4,4-substitied pyranopyrazole (SPP, 5) were reported via two-, three-, four- and fivecomponent reactions (MCRs). Methods: This review article compiles the preparation of pyrano[2,3-c]pyrazole derivatives, and it highlights the applications of various pyrano[2,3-c]pyrazole derivatives in medicinal chemistry. Results: Varieties of pyrano[2,3-c]pyrazole derivatives were achieved via “One-pot” multicomponent reactions (MCRs). Different reaction conditions in the presence of a catalyst or without catalysts were adapted to prepare the pyrano[2,3-c]pyrazole derivatives. Conclusion: Biologically active pyrano[2,3-c]pyrazole derivatives were prepared and used in drug discovery research.

Synthesizing s-triazine dendrimers are interesting as they can be synthesized easily, contain diversity in composition, and have a basic potential for molecular recognition. Triazine trichloride is the molecule of choice for synthesizing a novel class of dendrimers as it possesses certain remarkable characteristics like the potential to expand the chemical functionality by nucleophilic aromatic substitution reactions at various temperatures to give the desired dendrimer.

The improvement of new synthetic routes towards thiophene, oxazole, triazole, pyrimidine, pyridine, quinolone, coumarin, imidazopyrimidine, pyridoimidazole and triazolo[1,5-a] pyridine for their biological and medicinal exploration is an appealing vicinity for researchers. This review focuses on the utility of 1-(4-substituted-aminophenyl) ethanones and their derivatives as critical intermediates for the synthesis of these systems developed within the closing decade.

Quinoline-5,8-dione and naphthoquinone nuclei are very important substructures in industrial chemicals and pharmaceuticals. These compounds exhibit a wide variety of activities, including antifungal, antibacterial, antimalarial, antineoplastic, anticoagulant, anticancer, antiviral, radical scavenging, antiplatelet, trypanocidal, cytotoxic, and antineoplastic activities. Currently, several research articles on the importance of many natural and synthetic drugs containing quinolinequinone have been reported. This review covers the progress in quinolinequinone and naphthoquinone chemistry over the last five decades.

Plastic films play an important role in China's agricultural production. However, the large-scale use of plastic film has also caused very serious agricultural film pollution. Biodegradable polymers have received much attention because of the environmental pollution caused by the traditional plastic mulching film. The most typical copolymer is poly (butylene adipate co butylene terephthalate) (PBAT). Poly (Butylene Adipate-co-Terephthalate) (PBAT) is a kind of aliphaticaromatic polyester with excellent biodegradability and mechanical processing properties. Therefore, it has been rapidly developed and widely used in the industry. However, the degradation period of the agricultural film depends on certain requirements. Currently, the degradable materials available in the market do not meet the needs of all crops due to their degradation period. In this paper, the basic properties, degradation process and methods to delay the degradation of PBAT are reviewed for improving the degradation period of the plastic film that is prepared by using this kind of material. The degradation process includes photodegradation, biodegradation, and hydrolysis. The methods of delaying the degradation process include adding a chain extender, light stabilizer, antihydrolysis agent and antibacterial agent, providing a theoretical basis for the research and development of biodegradable film with a controllable degradation cycle. The future research and development of biodegradable polymers will mainly focus on controllable degradation rate, stable degradation cycle, new materials, and reducing research and development costs.

Organocatalysis has become a powerful tool in organic synthesis for the formation of C-C and C-X (N, S, O, etc.) bonds, leading to the formation of complex molecules from easily available starting materials. It provides an alternative platform to the conventional synthesis and fulfills the principles of green chemistry. During the last decades, taurine has emerged as a promising organocatalyst in an array of organic transformations in addition to its plentiful biological properties. It is highly stable, easy to store and separate, water-soluble, of low cost, easily available, and recyclable. The present article highlights the recent and up-to-date applications of taurine in organic transformations.

The biological and medicinal properties of thieno[3, 2-c] quinoline have prompted enormous research aimed at developing synthetic routes for these systems. This review focuses on the chemical properties associated with this system. The most reported reactions are Bischler- Napieralski, Suzuki−Miyaura−Schlüter, Pictet-Spengler, Stille coupling and Friedlander and Beckmann rearrangement reaction.

The C-H and N-H functionalization of indoles is an interesting area of research that has a useful impact on organic synthesis due to the availability of chiral indole scaffolds in the discovery of drugs, synthetic bioactive compounds, and natural products. The Chiral Phosphoric Acid catalysts (CPAs) have proven to be a powerful and versatile class of enantioselective organocatalysts. Many asymmetric syntheses of organic compounds have been carried out with these catalysts in C-C and CN bond formation reactions, and great progress has been reported. By 2011, several reviews were published covering some important topics and recent achievements in this field. Therefore, in this review, the most recent advances, research breakthroughs with key examples involving mechanisms of CPA-catalyzed C-H and N-H functionalization of indoles to form central chirality via Friedel Crafts, Michael type, and rearrangement reactions were reviewed and reported.