Mini-Reviews in Organic Chemistry - Volume 19, Issue 2, 2022

This mini review concerns hydrocarbons, (CH)n, and carbon allotropes, Cn, and their relationships with regular solids and regular surfaces, respectively. Platonic and Archimedean solids and surfaces related to carbon allotropes are described as an introduction. An overview is then provided on how Stone-Wales defects lead to a series of structures: pentaheptite, Haeckelite, net C, net W, planar C4, biphenylene, graphyne, graphdiyne, and tetraoctite. This last compound is discussed in detail together with its relation to the Mills-Nixon effect on cyclooctatetraene (COT).

Cinchona alkaloids are natural products extracted from cinchona plants, which contain quinine, quinidine, cinchonine, and cinchonidine. During the past 30 years, due to their attractive structural properties, these compounds have been used as chiral skeletons and organocatalysts in asymmetric organic synthesis. In this review, we summarize the applications of cinchona alkaloids derivatives in asymmetric catalysis recently developed by our group, including oxidation, reduction, and C-C bonds formation. These studies have solved some of the problems with the various asymmetric reactions discussed, while also enriching alkaloids chemistry, providing new ideas for the design and synthesis of chiral catalysts, and providing abundant experimental data for the chiral induction process.

Heterocyclic compounds play a vital role in the development of novel compounds because of their diverse pharmacological activities. Thiazine is a six-membered heterocyclic moiety. Various thiazine derivatives were synthesized or isolated from natural sources like plants and animals. Thiazine derivatives have varieties of pharmacological activities such as antimicrobial, antibacterial, antifungal, antiviral, anti-inflammatory, anticoagulant, anticancer, antihypertensive, and other useful biological as well as chemical applications. In the therapy of antimicrobial infections, new antimicrobial agents are needed because current antimicrobials have developed drug resistance. So, we discussed some thiazine derivatives, which exhibited antimicrobial activity.

α-Functionally substituted α,β-unsaturated aldehydes belong to the highly reactive class of compounds. They are used as versatile building blocks in organic synthesis. Due to the presence of several reactive sites in their structure, α,β-unsaturated aldehydes are widely employed as precursors of various acyclic and heterocyclic compounds, as well as complex natural products. At the same time, the acrylic systems with heteroatomic substituents (OAlk, SAlk) in the α-position are poorly studied. Therefore, it is impossible to establish the distribution of electron density reliably and evaluate the real reactivity of each new representative of this class of compounds. This minireview summarizes the works demonstrating the broad applicability of 3-substituted 2-alkoxy and 2- alkylthiopropenals in organic synthesis.

The research on the disease COVID-19 is an ongoing process since its outbreak as a pandemic. The repurposing of existing approved drugs has received priority attention due to some promising results obtained regarding COVID-19. In this article, some of the important chemical methodologies adopted for the synthesis of umifenovir, (s)-cidofovir, ribavirin, and ruxolitinib have been discussed. The repurposing of these approved drugs has received priority attention due to some promising results obtained regarding COVID-19 and some drugs are under more therapeutic trials. This manuscript has highlighted the synthetic strategies of four heterocyclic-based approved drugs, umifenovir, (s)-cidofovir, ribavirin, and ruxolitinib, repurposed for the treatment of COVID-19.

Seco-tetracyclic and seco-pentacyclic triterpenoids are a special class of triterpenoids with ring/rings cleaved on the original skeleton structures. A class of important triterpene derivatives, secotetracyclic and seco-pentacyclic triterpenoids, have long stimulated the interest and attention of botanists and natural products chemists. There is no systematic and comprehensive review for them. This review is focused on the phytochemical investigations and biological activities of seco-tetracyclic and seco-pentacyclic triterpenoids from nature, covering the literature from 2000-2019. This review describes 310 seco-tetracyclic and 139 seco-pentacyclic triterpenoids discovered from 154 species belong to 97 genera, which cover the chemical structures, types, sources, and bioactivities of compounds. The literature from 2000-2019 is reviewed and 208 references are cited.

It has been found that the metallic nanomaterials with mimetic enzyme activity have multiple oxidoreductase-like enzyme activities, such as horseradish peroxidase, glutathione peroxidase, catalase, oxidase, glucose oxidase, etc. In recent years, many applied researches based on these nanozymes have been reported. This review summarizes three kinds of representative nanozymes, including metal nanomaterials, MOFs, metal oxide nanomaterials, and their corresponding applications in sensing and biosensing.

Benzothiazole is a heterocyclic compound that contains a benzene ring fused with a fivemember 1,3-thiazole ring. Several types of research have established its potential as an antimicrobial agent, anticancer agent, anti-epileptic agent, antiviral agent, etc. Nowadays, various effective drugs utilize the hybridization of two or more pharmacophores in a single-molecule for synergizing its pharmacological action or to interact with more than one target or to reduce the side effects associated with it. In this article, various strategies for the synthesis of different pharmacologically active hybrid compounds containing benzothiazole with different substituents are highlighted. Apart from presenting the synthesis strategies, the article also highlights various pharmacological actions and molecular interactions with different biological molecules of the potential drugs containing benzothiazole.

Fungi are considered a prosperous pool of microbial bio-metabolites. Terretonins are meroterpenoids that are reported mainly from the Aspergillus genus. They exhibit unique tetracyclic core skeletons and various bioactivities. The current review summarizes the published researches on the source, biosynthesis, isolation, structural characterization, and bioactivities of terretonins that have been reported from Aspergillus species, as well as from synthetic sources. A literature search on the published studies was conducted over different databases, including Web of Science, MedLine (PubMed), Scopus, SpringerLink, Google Scholar, SciFinder, Wiley, and ACS Publications up to 2020. In this work, 18 compounds from Aspergillus species and synthetic sources are depicted. They have unrivaled and diversified skeletons as well as various bioactivities. Moreover, 37 references are included. Terretonins form a class of fungal bio-metabolites that attain all the characters for becoming lead compounds in their particular therapeutic category.