Chapter Four - Heterocycles from Donor–Acceptor Interactions

The diverse synthesis of heterocyclic compounds has always been one of the popular subjects of organic chemistry. To this end, great efforts have been devoted to developing new reagents and establishing new strategies and methods concerning efficiency, selectivity and sustainability. β-Oxodithioesters and their enol tautomers (i.e., α-enolic dithioesters), as a class of simple and readily accessible sulfur-containing synthons, have been widely applied in the construction of various five- and six-membered heterocycles (e.g., thiophenes, thiopyrans, thiazoles, pyridines and quinolines) and other useful open-chain frameworks. Due to their unique chemical structures, β-oxodithioesters bear multiple reaction sites, which enable them to participate in two-component or multicomponent reactions to construct various heterocyclic compounds. In the past decade, the application of β-oxodithioesters in the synthesis of heterocycles has made remarkable progress. Herein, an update on the recent advances in the application of β-oxodithioesters in the synthesis of heterocycles during the period from 2013 to 2023/06 is provided. According to the different types of rings concerning heteroatoms in products, this review is divided into five sections under discussion including (i) synthesis of sulfur-containing heterocycles, (ii) synthesis of sulfur and nitrogen-containing heterocycles, (iii) synthesis of nitrogen-containing heterocycles, (iv) synthesis of nitrogen and oxygen-containing heterocycles, and (v) modification to other open-chain frameworks.

Cancer is a very complex disease, linked with different initiating causes, cofactors and promoters, and several types of cellular damages. There is a strong correlation between chronic inflammatory conditions in a particular organ and cancer specific to that organ. The longer the inflammation persists, the higher the risk of associated carcinogenesis. Drug discovery process has changed dramatically over the past decade as there is an increasing demand to obtain more drug candidates and decrease attrition during drug development. Chromone scaffold [(4H)-1-benzopyran-4-one] has been recognized as a pharmacophore of a large number of bioactive molecules of either natural or synthetic origin. Until now, numerous biological effects such as anti-inflammatory, antitumoral, and antimicrobial activities especially in popular medicine, have been attributed to this benzo-γ-pyrone nucleus. Compounds of this type also possess inhibition properties towards different enzymes such as oxidoreductases, kinases, tyrosinases, lipoxygenases and cyclooxygenases. Chemotherapeutic agents like tetrahydropyridine (THP) analogs exhibit diverse biological activities like analgesic and anti-inflammatory effects. Our earlier research results indicated that some of the THP derivatives showed COX-2 inhibition and anti-inflammatory activities on rat paw edema assay studies. Incorporation of THP moiety might enhance biological activity of the chromone derivatives. Herein, we report the synthesis of substituted N-(5,6-dihydropyridin-1-(2H)-yl)-4-oxo-4H-chromene-2-carboxamide as anticancer and anti-inflammatory agents. The starting material 4-oxo-4H-chromene-2-carbonyl chloride was obtained by the reaction of 4-oxo-4H-chromene-2-carboxylic acid, dissolved in 1,2-dichloroethane and SOCl2 containing few drops of DMF under reflux for 4h. The crude acid chloride obtained by removing the excess of SOCl2 and solvent under vaccum, was used immediately for next step. Reaction of the acid chloride with substituted N-amino pyridinium salt in anhydrous tetrahydrofuran gave stable ylides. This was followed by reduction with sodim borohydride in absolute ethanol, which furnished the target compound. These compounds were evaluated for their cytotoxic effects on MCF-7 ER positive breast cancer cells, MDA-MB ER receptor negative breast cancer cells, and Ishikawa cell line using the CellTiter-Glo (CTG) luminescent cell viability assay. N-(4-tert-butyl-5,6-dihydropyridin-1(2H)-yl)-6-chloro-7-methyl-4-oxo-4H-chromene-2-carboxamide showed the cytotoxicity with an IC50 values of 73.28 μM on MDA-MB-231 cell lines. This research was supported by the National Center for Research Resources and the National Institute of Minority Health and Health Disparities of the National Institutes of Health through Grant Number 8 G12MD007582-28. Citation Format: Kinfe Ken Redda, Madhavi Gangapuram, Mohammad A. Ghaffari, Suresh Eyunni, Nelly Mateeva, Bereket Mochona. Synthesis of heterocyclic compounds as anticancer agents. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2229. doi:10.1158/1538-7445.AM2013-2229

Considering the very important medicinal and biological properties of heterocycles incorporated indole skeleton, synthesis of these compounds is of great interest to medicinal and organic chemists, especially researchers who are involved in the synthesis of heterocycles. The present review focuses on the recent investigation in the synthesis of heterocycles with indole moiety using indole derivatives as reactant via multi-component reaction for the period of 2012–2022. Reports were categorized based on the type of indole substitution. The main aim of this review is to provide a summary of recently reported methods in the use of indole derivatives in multicomponent synthesis of heterocyclic compounds for organic and medicinal chemists.

Heterocycles constitute the largest and the most diverse family of organic compounds. Among them, aromatic heterocycles represent structural motifs found in a great number of biologically active natural and synthetic compounds, drugs, and agrochemicals. Moreover, aromatic heterocycles are widely used for synthesis of dyes and polymeric materials of high value. 1 There are numerous reports on employment of aromatic heterocycles as intermediates in organic synthesis. 2 Although, a variety of highly efficient methodologies for synthesis of aromatic heterocycles and their derivatives have been reported in the past, the development of novel methodologies is in cuntinious demand. Particlularly, development of new synthetic approaches toward heterocycles, aiming at achieving greater levels of molecular complexity and better functional group compatibilities in a convergent and atom economical fashions from readily accessible starting materials and under mild reaction conditions, is one of a major research endeavor in modern synthetic organic chemistry. Transition metal-catalyzed transformations, which often help to meet the above criteria, are among the most attractive synthetic tools. Several excellent reviews dealing with transition metal-catalyzed synthesis of heterocyclic compounds have been published in literature during recent years. Many of them highlighted the use of a particular transition metal, such as gold,3 silver,4 palladium,5 copper,6 cobalt,7 ruthenium,8 iron,9 mercury,10 rare-earth metals,11 and others. Another array of reviews described the use of a specific kind of transformation, for instance, intramolecular nucleophilic attack of heteroatom at multiple C–C bonds,12 Sonogashira reaction,13 cycloaddition reactions,14 cycloisomerization reactions,15 C–H bond activation processes,16 metathesis reactions,17 etc. Reviews devoted to an application of a particular type of starting materials have also been published. Thus, for example, applications of isocyanides,18 diazocompounds,19 or azides20 have been discussed. In addition, a significant attention was given to transition metal-catalyzed multicomponent syntheses of heterocycles.21 Finally, syntheses of heterocycles featuring formation of intermediates, such as nitrenes,22 vinylidenes,23 carbenes, and carbenoids24 have also been reviewed. The main focus of the present review is a transition metal-catalyzed synthesis of aromatic monocyclic heterocycles. The organization of the review is rather classical and is based on a heterocycle, categorized in the following order: (a) ring size of heterocycle, (b) number of heteroatoms, (c) type of heterocycle, and (d) a class of transformation involved. A brief mechanistic discussion is given to provide information about a possible reaction pathway when necessary. The review mostly discusses recent literature, starting from 200425 until the end of 2011, however, some earlier parent transformations are discussed when needed.

The synthesis of heterocyclic compounds is very interesting topic among synthetic chemists because these compounds are widely used in various fields, especially in medicinal chemistry. In this category, polyhydroquinoline derivatives have attracted profound attention among synthetic chemists because these derivatives are used as anti-virus, anti-tumor, anti-fungal, anti-bacterial and anti-cancer agents. Therefore, the design of novel, ecofriendly and efficient catalytic systems for their preparation is an important challenge in organic synthesis. In this article, we designed and constructed a novel and environmentally benign solid catalyst was fabricated by grafting tetra dentate picolinic acid-Cu complex active species onto the 3,4-Diaminobenzoic acid functionalized Fe3O4 support [Fe3O4@DABA-PA-CuBr2] for the synthesis of polyhydroquinolines under ecofriendly conditions. The results of these experiments clearly show that this catalytic system is very efficient in the synthesis of polyhydroquinolines because the desired products were synthesized with high to excellent yields. Finally, the reusability investigation indicated that the synthesized catalyst possessed sufficient recyclability of up to eight times with negligible drop in the catalytic activity.

Fluorine-Containing Heterocycles. Part I. Synthesis by Intramolecular Cyclization

The Synthesis of Heterocyclic Compounds with Hypervalent Organoiodine Reagents

For Abstract see ChemInform Abstract in Full Text.

Review: 1074 refs.

Chapter 4 - A chapter on synthesis of various heterocyclic compounds by environmentally friendly green chemistry technologies

BackgroundHeterocyclic compounds have always been used as a core portion in the development of anticancer drugs. However, there is a pressing need for developing inexpensive and simple alternatives to high-cost and complex chemical agents-based catalysts for large-scale production of heterocyclic compounds. Also, development of some smart platforms for cancer treatment based on nanoparticles (NPs) which facilitate Fenton reaction have been widely explored by different scientists. Magnetic NPs not only can serve as catalysts in the synthesis of heterocyclic compounds with potential anticancer properties, but also are widely used as smart agents in targeting cancer cells and inducing Fenton reactions. Aim of ReviewTherefore, in this review we aim to present an updated summary of the reports related to the main clinical or basic application and research progress of magnetic NPs in cancer as well as their application in the synthesis of heterocyclic compounds as potential anticancer drugs. Afterwards, specific tumor microenvironment (TME)-responsive magnetic nanocatalysts for cancer treatment through triggering Fenton-like reactions were surveyed. Finally, some ignored factors in the design of magnetic nanocatalysts- triggered Fenton-like reaction, challenges and future perspective of magnetic nanocatalysts-assisted synthesis of heterocyclic compounds and selective cancer therapy were discussed.Key Scientific Concepts of Review:This review may pave the way for well-organized translation of magnetic nanocatalysts in cancer therapy from the bench to the bedside.

Chapter 5 - Green Solvents for Eco-friendly Synthesis of Bioactive Heterocyclic Compounds

Heterocyclic compounds are widely distributed in natural products, pharmaceuticals and materials, thus drawing considerable attention from the synthetic communities. Generally, alkaline earth metals are earth-abundant and environmentally friendly compared to precious metals. To date, researchers have achieved great progress in utilization of alkaline earth metals in the syntheses of various heterocyclic compounds. Herein, this review will summarize recent advances in the syntheses of heterocyclic compounds enabled by alkaline earth metals, including magnesium, calcium and strontium. In addition, the summary is also presented.

4-Hydroxycoumarins are some of the most versatile heterocyclic scaffolds and are frequently applied in the synthesis of various organic compounds. 4-Hydroxycoumarin-based compounds are important among heterocyclic structures due to their biological and pharmaceutical activities. In this study, we provide an overview on the recent applications of 4-hydroxycoumarin in multicomponent reactions for the synthesis of various heterocyclic compounds during the time period of 2015-2018.

Nucleophilic phosphine catalysis is a practical and powerful tool for the synthesis of various heterocyclic compounds with the advantages of environmentally friendly, metal-free, and mild reaction conditions. The present report summarizes the construction of four to eight-membered heterocyclic compounds containing nitrogen, oxygen and sulphur atoms through phosphine-catalyzed intramolecular annulations and intermolecular [2+2], [3+2], [4+1], [3+1+1], [5+1], [4+2], [2+2+2], [3+3], [4+3] and [3+2+3] annulations of electron-deficient alkenes, allenes, alkynes and Morita-Baylis-Hillman carbonates.