Mini-Reviews in Organic Chemistry - Volume 22, Issue 3, 2025

Free radical reactions occupy an important position in synthetic organic chemistry as well as medicinal chemistry, significantly complementing and extending the synthesis of coumarin or quinolin-2-one compounds. Moreover, the use of constructing coumarin or quinolin-2-one compounds functionalized at the C3 position has certain advantages over traditional noble metal-catalyzed or high-temperature cyclization, which is more in line with the advocates of green chemistry. The design of alkenes or alkynes as radical acceptors for cascade reactions presents a novel and robust approach to obtaining coumarin or quinolin-2-one molecules. These radical cascade cyclization reactions have been well explored and studied over the past decade. As a result, we have compiled a mini-review of the rapidly developing cutting-edge research in this field, featuring typical examples and in-depth exploration of the underlying mechanisms.

Pyrimido [5, 4-c] quinolone derivatives are significant synthetic targets that show numerous interesting biological activities. The pyrimido [4, 5-b] quinoline is the most famous source of these derivatives, which has been used in medicine to antitumor and target different diseases. Since the segregation of quinoline derivatives, many synthetic methodologies were advanced for their synthesis. Despite the current interesting findings on this class of pyrimidoquinoline, the chemical literature deficits a comprehensive summary of the synthetic methodologies and biological activities of pyrimido [5, 4-c] quinoline derivatives. This review focuses on recent advances in pyrimido [5, 4-c] quinolines chemistry via debating diverse synthetic ways developed for the preparation of pyrimido [5, 4-c] quinolines and other unique derivatives that exhibited promising biological activities. Also, it sheds light on the most widespread reactions of pyrimidoquinolines and the employment of these derivatives as the essential building blocks for different biologically active compounds:. Among these reactions used to prepare pyrimido [5, 4-c] quinoline derivatives are the following: Biginelli-type one or three-component reaction, Micheal addition, intermolecular cyclization, cyclo-condensation, acylation, Vielsmeir formylation, Suzuki cross-coupling reaction, transformation, oxidation-reduction, esterification, dehydration, decarboxylation, methylation, chlorination, alkylation.

Gem-dimethyl bicyclic [3.1.0] proline, an azadicyclohexane derivative, constitutes a prevalent skeleton structure in drugs, which serves an important role in the synthesis of antiviral drugs, such as Nirmatrelvir, Boceprevir, Narlaprevir, etc. This study offers a comprehensive overview of the documented synthetic strategies for gem-dimethyl bicyclic [3.1.0] proline methyl ester and delves into the application characteristics of each synthetic strategy. These synthetic approaches can be divided into three major types: the first synthetic method uses proline derivatives as the starting material, the second one uses cyclopropane derivatives as the starting material, and the third one uses the bicyclic skeleton as the starting material. Of these strategies, the third method stands out as the most extensively adopted.

In chemistry, thiazoles and their derivatives constitute a significant class of biologically active molecules that are thought to be the fundamental building blocks of numerous other biologically active compounds. Many synthetic pharmaceuticals, including fungicides, dyes, antimicrobials, and anticonvulsants, are made using thiazoles and their derivatives as an intermediary. Thus, one of the main areas of organic synthesis research is the presentation of effective and environmentally acceptable catalytic methods for the synthesis of thiazole derivatives. Over the past ten years, organic synthesis in chemistry has been completely transformed by the use of magnetic nanocomposites as catalysts. Magnetic nanoparticles are very stable and easily manipulated on the surface, which can result in the creation of an efficient catalyst. The main feature of magnetic nanocatalysts is their ability to be easily separated from the reaction mixture using only an external magnet. In recent years, several magnetic nanocatalysts have been reported to produce various thiazole compounds. We will look at these methods and talk about the characteristics of these catalytic systems in this post. This review will be helpful for synthetic chemists who are interested in magnetic nanocatalysts and working in the field of thiazole synthesis.

meta-Chloroperbenzoic acid (mCPBA) is a readily available peroxide that is a powerful oxidizing agent utilized in a range of oxidative reactions. Metal-free oxidations mediated by mCPBA involving selective oxidation of aliphatic amines to oximes, selective oxidation of organosulphides/aldehydes, synthesis of heterocyclic N-oxides, domino C[sp²] hydroxylation/annulation of enaminones (heterocyclic ring formation), acid to phenol conversion, oxidation of exocyclic C=C bond, oxidative ring contraction, etc. have been comprehensively and critically examined in this review from 2015 to date.

Indole alkaloids are a class of secondary metabolites with a wide range of biological activities. The chemical structure of indole alkaloids is relatively complex, but all of them have a remarkable structural feature, which is a five-membered pyrrole cyclocyclobenzene ring. Because of the unique structural characteristics of indole alkaloids, they have also a wide range of pharmacological activities, such as antibacterial, anti-inflammatory, anti-tumor, anti-viral, anti-hepatitis, anti-diabetes, neuroprotective, lipid-lowering and so on. For example, indole alkaloids have been shown to show anticancer activity through various anti-proliferation mechanisms and play an important role in the research of novel cancer treatment advances. In this article, we reviewed the recent progress of indole alkaloids isolated from microorganisms and their chemical and biosynthesis, which laid a foundation for further utilization and development of indole alkaloids.

The synthesis of organic molecules has been a tremendous and rapid advance in the recent decade to obtain high biological and pharmacological activities. In this review, the organic synthesis of pyrimido[4,5-b]quinoline derivatives is considered an alternative method to traditional procedures for treating many diseases that affect humans. Also, by transferring electrons, stereoselective syntheses occur via organic reactions in various unnatural and natural conditions at room temperature and normal pressure. We found that the structure of pyrimido[4,5-b]quinoline derivatives was formed by substrates, bases, electrophiles, and low-level and highly stable reagents that can be broadly applied to synthesize more heterocycles. These reagents include: 2-nitrobenzaldehyde; 3-(benzyloxy)-4-methoxy-2-nitrobenzaldehyde; 4,5-dimethoxy-2-nitrobenzal-dehyde; 2-aminobenzaldehyde; 2-aminoquinoline-3-carboxamide; 2-chloroquinoline-3-carbal-dehyde; 2-bromobenzaldehyde; 2-chloroquinoline-3-carbonitrile; 2-chloroquinoline-3-carboxylic acid; aniline; phenyl-methanamine; amino-quinoline-3-carboxylic acid /amino-quinoline-carbonitrile; amino-6,7-dimethoxy-quinoline-3-carbonitrile; amino-oxolo [4,5-g]quinolin-carboxamide; 3-(aminomethyl) quinolin-2-amine; 4-aminobenzo[d][1,3] dioxole-5-carbaldehyde; thiourea; ethyl 3-oxo-butanoate; 2-cyano-acetamide; 2-(bis (methylthio) methylene) malononitrile; ethyl 3,3-diamino-2-cyanoacrylate; naphthalene-1,4-dione; and N-carbamoyl-2-cyanoacetamide derivatives. The prepared pyrimido[4,5-b]quinoline derivatives were described through means of the following chemical reactivity: alkylation, bromination, chlorination, cyclocondensation, cyclization, acylation, oxidation-reduction, dehydration, addition reaction and Vilsmeier-Haack reaction (Vilsmeier reagent).