China
Africa
Explore chapters and articles related to this topic
Recent Advancements in the Pharmacotherapeutic Perspectives of Some Chalcone Scaffold Containing Natural Compounds as Potential Anti-Virals
Published in Debarshi Kar Mahapatra, Cristóbal Noé Aguilar, A. K. Haghi, Natural Products Pharmacology and Phytochemicals for Health Care, 2021
Debarshi Kar Mahapatra, Sanjay Kumar Bharti, Vivek Asati
These natural low molecular weight ligands convert into flavonoid (by acid) and reverse back into flavanone (by base) and find application in the structural elucidation of chromanochromane, tannin, flavanone, and flavonoid. In addition to it, they are an excellent template for synthesizing numerous pharmacotherapeutically active synthetic scaffolds like benzodiazepine, thiadiazole, benzoxazepine, benzothiazepine, pyrazole, isoxazole, pyrimidine, pyrazoline, etc., which expressed multifarious actions against protozoal infections, bacterial infections, sleep disorder, trypanosomiasis, anxiety, gout, malaria, epilepsy, hypertension, reduced immune response, diabetes, tuberculosis, leishmaniasis, ulcer, fungal infections, cancer, thrombosis, reactive oxygen species, inflammation, HIV, metastasis, etc. [16, 17]. Non-pharmacological applications in daily human life rest with a scintillator, insecticides, polymerization agents in product development, sweeteners in confectionaries, catalyst in specific reactions, chemosensor for detection, fluorescent polymeric agents, chromophores in dying industries, fluorescent whitening agent, etc. [18].
Diversity-Oriented Synthesis of Substituted and Fused β-Carbolines from 1-Formyl-9H-β-Carboline Scaffolds
Published in Tanmoy Chakraborty, Lalita Ledwani, Research Methodology in Chemical Sciences, 2017
Nisha Devi, Ravindra K. Rawal, Virender Singh
Substituted 1-formyl-9H-β-carbolines (52) were also demonstrated to be viable precursors for the synthesis of a library of new β-carboline-based polycyclic systems via 1,3-dipolar cycloaddition reaction.32 The dienophile introduced at N–H of B-ring in the form of allyl or propargyl in 1-formyl-9H-β-carbolines (2, 5, 36) was achieved through a modified route via initial N-alkylation of acetal 35 with allyl or propargyl bromide in the presence of Cs2CO3 to generate 51 followed by deprotection of formyl group to afford the N-substituted derivatives (52). Initially, aldehydes 52 were transformed to oximes 93 via treatment with NH2OH·HCl (Scheme 5.35). Intramolecular 1,3-dipolar cycloaddition of nitrile oxide 93 led to the formation of novel isoxazole or isoxazoline derivatives (94).
Microwaves in Lactam Chemistry
Published in Banik Bimal Krishna, Bandyopadhyay Debasish, Advances in Microwave Chemistry, 2018
Dr. Debasish Bandyopadhyay, Bimal Krishna Banik
Aside from lactam cores, some other heterocyclic scaffolds, for example, 1,4-thiazepine, carbazole, indole, quinoline, pyrrole, pyrimidine, quinoxaline, pyrazole, pyrazine, coumarin, isoxazole, etc. have occupied a special place in medicinal chemistry and drug discovery research because of their remarkable pharmacological profiles. A huge number of commercial drugs contain one (or more) of these unique motifs as a core unit. To achieve enhanced biological activity an attempt was made to fuse the seven-membered 1,4-thiazepine nucleus with either carbazole or pyrazole or isoxazole pharmacophore. Microwave-induced, eco-friendly, diversity-oriented synthesis of fused heterocycles, 1,4-thiazepine fused with another bioactive heterocyclic scaffold (carbazole, pyrazole, or isoxazole), was reported by Shi and co-workers [110]. This one-pot three-component reaction was carried out in a solventless condition (Scheme 10.27) with an excellent yield of the products (>90% in all the cases except for 4-bromophenyl, 76%). All the newly synthesized fused ε-lactams (68) were evaluated for antioxidant activity and anticancer activity against HCT 116 (human colon carcinoma cell lines) and mice lymphocytes. The antioxidant activity was evaluated considering the scavenging capacity of 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH), superoxide anion, and hydroxyl free radicals. A few tested compounds showed strong capability for scavenging DPPH, superoxide anion, and hydroxyl free radicals in comparison to positive control L-ascorbic acid. Some of these compounds also inhibited the growth of HCT-116 cell lines more selectively than mice lymphocytes.
[3 + 2] Cycloaddition reactions of nitrile oxides generated in situ from aldoximes with alkenes and alkynes under ball-milling conditions
Published in Green Chemistry Letters and Reviews, 2022
Run-Kai Fang, Zheng-Chun Yin, Jun-Shen Chen, Guan-Wu Wang
Isoxazoles and isoxazolines are important structures in organic chemistry and pharmaceutical chemistry, which widely exist in various natural compounds and synthetic drugs (20–22). They often display versatile pharmacological activities, such as anti-cancer and anti-tumor activities (23–24), antibacterial activities (25), analgesic and anti-inflammatory activities (26), and so on (27–28). On the other hand, they are also important intermediates in organic synthesis and important precursors for the synthesis of β-hydroxyl ketones, β-amino acids and γ-amino alcohols (29–34). Given the widespread utility of isoxazoles and isoxazolines, it is not surprising that a variety of methods have been developed for their synthesis. The [3 + 2] cycloaddition of nitrile oxides with various alkenes and alkynes is an important strategy to synthesize isoxazoles and isoxazolines. The formation of nitrile oxides relies heavily on oxidation of aldoximes. In the past decades, quite a number of oxidants have been reported (35–42). However, most oxidants either require complex preparation or produce toxic byproducts. Therefore, the development of convenient and green strategies toward isoxazoles and isoxazolines is highly desirable.