Current Organic Chemistry - Volume 24, Issue 14, 2020

Plants of the genus Piper (Piperaceae) have a pantropical distribution. In Brazil, Piper species are used in traditional medicine to treat many diseases such as inflammation, diabetes, toothache, and fever. Many reports have shown a correlation between the biological activities of Piper species and neolignans, a secondary metabolite class obtained from the shikimic acid biosynthetic pathway. This review aims to provide detailed information on the structural identification of neolignans isolated from Piper species by 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy. These searchable data enable rapid identification and routine analysis of neolignans from extracts of the Piper species.

Among the major class of heterocycles, the N-heterocycles, such as pyrazoles, are scaffolds of vast medicinal values. Various drugs and other biologically active molecules are known to contain these N-heterocycles as core motifs. Specifically, arylpyrazoles have exhibited a diverse range of biological activities, including anti-inflammatory, anticancerous, antimicrobial and various others. For instance, arylpyrazoles are present as core moieties in various insecticides, fungicides and drugs such as Celebrex and Trocoxil. The present review will be highlighting the significant therapeutic importance of pyrazole derivatives developed in the last few years.

Catalytic C-H activation is a powerful method for organic synthesis. In recent years, scientists have made great progress by developing transitional metals for catalyzing CH functionalization reaction. In this review, we summarized and highlighted recent progress in C-H activation with copper, cobalt, iron, manganese, and nickel as catalysts.

Barbituric, thiobarbituric acids and their related analogs are reactive synthons for the synthesis of drugs and biologically, and pharmaceutically active pyrimidines. The present review aimed to summarize the recent advances in the synthesis of different alkylsubstituted, fused cycles, spiro-, and binary heterocycles incorporated pyrimidine skeleton based on barbituric derivatives. In this sequence, the eco-friendly techniques under catalytic conditions were used for the diverse types of multicomponent reactions under different conditions for the synthesis of various types of heterocycles. Nano-catalysts are efficient for the synthesis of these compounds in high yields and effective catalyst reusability. The compounds are potent antibacterial, cytotoxic, xanthine oxidase inhibitory activities, and attend as urease inhibitors. The projected mechanisms for the synthesis of pyranopyrimidines, benzochromenopyrimidines, chromeno-pyranopyrimidines, spiroxyindoles, oxospiro-tricyclic furopyrimidines, pyrimidine-based monoand bicyclic pyridines were discussed. The potent and diverse biological activities for instance, antioxidant, antibacterial, cytotoxic, and xanthine oxidase inhibitory activities, as well as urease inhibitors, are specified.

Kojic acid, one of the most widespread 3-hydroxypyran-4-one derivatives, displays a wide range of biological activities and found application in food as well as cosmetics industry. The synthesis of kojic acid derivatives has provoked great interest as an easily available and biologically active precursor among organic and medicinal researchers. Multicomponent reactions, involving three or more reactants in one-pot thereby resulting in a structure with functional diversity are efficient methods for the promotion of green chemistry in the context of modern drug discovery. They offer several advantages over conventional stepwise protocols like simplicity, efficiency, selectivity, convergence and atom economy. This review aims to highlight the versatility of kojic acid as an important synthon in multicomponent reactions for the construction of various biologically relevant compounds such as pyrano[3,2- b]chromenediones, pyrano[3,2-b]pyrans, pyrano[2′,3′:5,6]pyrano[2,3-b]pyridines, spiro[indoline-3,4’-pyrano[3, 2-b]pyrans, 2-substituted kojic acid conjugates, etc.