Gallium(III) triflate-catalyzed synthesis of quinoxaline derivatives

Reusable nano-catalyzed green protocols for the synthesis of quinoxalines: an overview

Heterocyclic compounds are very widely distributed in nature and are essential for life activities. They play a vital role in the metabolism of all living cells, for example, vitamins and co-enzyme precursors thiamine, riboflavin etc. Quinoxalines are a class of N-heterocycles that are present in a variety of natural and synthetic compounds. The distinct pharmacological activities of quinoxalines have attracted medicinal chemists considerably over the past few decades. Quinoxaline-based compounds possess extensive potential applications as medicinal drugs, presently; more than fifteen drugs are available for the treatment of different diseases. Diverse synthetic protocols have been developed via a one-pot approach using efficient catalysts, reagents, and nano-composites/nanocatalysts etc. But the use of homogeneous and transition metal-based catalysts suffers some demerits such as low atom economy, recovery of catalysts, harsh reaction conditions, extended reaction period, expensive catalysts, the formation of by-products, and unsatisfactory yield of products as well as toxic solvents. These drawbacks have shifted the attention of chemists/researchers to develop green and efficient protocols for synthesizing quinoxaline derivatives. In this context, many efficient methods have been developed for the synthesis of quinoxalines using nanocatalysts or nanostructures. In this review, we have summarized the recent progress (till 2023) in the nano-catalyzed synthesis of quinoxalines using condensation of o-phenylenediamine with diketone/other reagents with plausible mechanistic details. With this review, we hope that some more efficient ways of synthesizing quinoxalines can be developed by synthetic chemists.

Ca(IO3)2 nanoparticles: fabrication and application as an eco-friendly and recyclable catalyst for the green synthesis of quinoxalines, pyridopyrazines, and 2,3-dicyano pyrazines

In this paper, calcium iodate nanoparticles were first synthesized by the modified reaction of Ca(NO₃)₂ and KIO₃ in an aqueous medium under ultrasonic irradiation. The structure of nanocatalyst was then characterized by FT-IR, FESEM, EDX, XRD, and BET techniques. Afterward, the fabricated Ca(IO₃)₂ was applied as a nanocatalyst in the facile synthesis of heterocycles including quinoxalines, 5,6-dicyano pyrazines, and pyrido[2,3-b]pyrazines. For this purpose, the feasibility of the reaction in the presence of different catalyst amounts, solvents, and temperatures was first investigated. Next, the target compounds were obtained by the condensation reaction of aryl-1,2-diamines or 2,3-diaminomaleonitrile with 1,2-diketones in the presence of a catalytic amount of Ca(IO₃)₂ in ethanol or acetic acid solvents at ambient temperature in good to excellent yields. One of the salient advantages of this work is the synthesis of calcium iodate nanoparticles by chemical precipitation method and its application as a heterogeneous nanocatalyst for the first time in the synthesis of organic compounds. The other important benefits of this process are the use of an inexpensive, safe, stable and recyclable catalyst, high product yields, short reaction times, and easy isolation of the product in pure form.

Synthesis and Photophysical Properties of Quinoxaline-Based Blue Aggregation-Induced Emission Molecules

A series of quinoxaline-based compounds 1–4 have been synthesized by Palladium-Catalyzed cross-coupling reaction and their photophysical properties have been extensively studied. Compounds 1–4 show deep blue light emission both in solution (λem ≤ 425 nm, CIEy≤0.03) and in solid-state. Moreover, compounds 1–3 show a non-typical aggregation-induced enhanced emission (AIEE), which would be effective deep blue light-emitting materials. The DFT calculation indicated that the HOMO energy levels of compounds 1–3 are distributed throughout the molecule, and the LUMO energy levels are mainly concentrated on the quinoxaline group. while the HOMO of compound 4 is mainly on the benzene ring at 2,3-position, and the LUMO is distributed both of the quinoxaline and the benzaldehyde group at the 6,7-position.

Regioselective Synthesis of Trisubstituted Quinoxalines Mediated by Hypervalent Iodine Reagents

A facile and regioselective synthesis of quinoxalines, an important motif in medicinal chemistry and materials sciences, was developed. Despite their prospective utility, the regioselective preparation of trisubstituted quinoxalines has not been previously established. In the reported system, hypervalent iodine reagents catalyzed the annulation between α-iminoethanones and o-phenylenediamines in a chemo/regioselective manner to afford trisubstituted quinoxalines. Excellent regioselectivities (6:1 to 1:0) were achieved using [bis(trifluoroacetoxy)iodo]benzene and [bis(trifluoroacetoxy)iodo]pentafluorobenzene as annulation catalysts.

Synthesis, Molecular Docking, and Biological Evaluation of 2,3-Diphenylquinoxaline Derivatives as a Tubulin's Colchicine Binding Site Inhibitor Based on Primary Virtual Screening

BACKGROUND AND OBJECTIVE

Tubulin inhibitors have proved to be a promising treatment against cancer. Tubulin inhibitors target different areas in microtubule structure to exert their effects. The colchicine binding site (CBS) is one of them for which there is no FDA-approved drug yet. This makes CBS a desirable target for drug design.

MATERIALS AND METHODS

Primary virtual screening is done by developing a possible pharmacophore model of colchicine binding site inhibitors of tubulins, and 2,3-diphenylquinoxaline is chosen as a lead compound to synthesis. In this study, 28 derivatives of 2,3-diphenylquinoxalines are synthesized, and their cytotoxicity is evaluated by the MTT assay in different human cancer cell lines, including AGS (Adenocarcinoma gastric cell line), HT-29 (Human colorectal adenocarcinoma cell line), NIH3T3 (Fibroblast cell line), and MCF-7 (Human breast cancer cell).

RESULTS

Furthermore, the activity of the studied compounds was investigated using computational methods involving molecular docking of the 2,3-diphenylquinoxaline derivatives to β-tubulin. The results showed that the compounds with electron donor functionalities in positions 2 and 3 and electron-withdrawing groups in position 6 are the most active tubulin inhibitors.

CONCLUSION

Apart from the high activity of the synthesized compounds, the advantage of this report is the ease of the synthesis, work-up, and isolation of the products in safe, effective, and high-quality isolated yields.

New quinoxaline-based VEGFR-2 inhibitors: design, synthesis, and antiproliferative evaluation with in silico docking, ADMET, toxicity, and DFT studies

A new series of 3-methylquinoxaline-based derivatives having the same essential pharmacophoric features as VEGFR-2 inhibitors have been synthesized and evaluated for their antiproliferative activities against two human cancer cell lines, MCF-7 and HepG-2. Compounds 15b and 17b demonstrated a significant antiproliferative effect with IC₅₀ ranging from 2.3 to 5.8 μM. An enzymatic assay was carried out for all the tested candidates against VEGFR-2. Compound 17b was the most potent VEGFR-2 inhibitor (IC₅₀ = 2.7 nM). Mechanistic investigation including cell cycle arrest and apoptosis was performed for compound 17b against HepG-2 cells, and the results revealed that 17b induced cell apoptosis and arrested cell cycle in the G2/M phase. Moreover, apoptosis analyses were conducted for compound 17b to evaluate its apoptotic potential. The results showed upregulation in caspase-3 and caspase-9 levels, and improving the Bax/Bcl-2 ratio by more than 10-fold. Docking studies were performed to determine the possible interaction with the VEGFR-2 active site. Further docking studies were carried out for compound 17b against cytochrome P450 to present such compounds as non-inhibitors. In silico ADMET, toxicity, and physico-chemical properties revealed that most of the synthesized members have acceptable values of drug-likeness. Finally, DFT studies were carried out to calculate the thermodynamic, molecular orbital and electrostatic potential properties.

Quinoxaline Moiety: A Potential Scaffold against Mycobacterium tuberculosis

Background. The past decades have seen numerous efforts to develop new antitubercular agents. Currently, the available regimens are lengthy, only partially effective, and associated with high rates of adverse events. The challenge is therefore to develop new agents with faster and more efficient action. The versatile quinoxaline ring possesses a broad spectrum of pharmacological activities, ensuring considerable attention to it in the field of medicinal chemistry. Objectives. In continuation of our program on the pharmacological activity of quinoxaline derivatives, this review focuses on potential antimycobacterial activity of recent quinoxaline derivatives and discusses their structure-activity relationship for designing new analogs with improved activity. Methods. The review compiles recent studies published between January 2011 and April 2021. Results. The final total of 23 studies were examined. Conclusions. Data from studies of quinoxaline and quinoxaline 1,4-di-N-oxide derivatives highlight that specific derivatives show encouraging perspectives in the treatment of Mycobacterium tuberculosis and the recent growing interest for these scaffolds. These interesting results warrant further investigation, which may allow identification of novel antitubercular candidates based on this scaffold.

Green Hydrothermal Synthesis of Fluorescent 2,3-Diarylquinoxalines and Large-Scale Computational Comparison to Existing Alternatives

Here, the hydrothermal synthesis (HTS) of 2,3-diarylquinoxalines from 1,2-diketones and o-phenylendiamines (o-PDAs) was achieved. The synthesis is simple, fast, and generates high yields, without requiring any organic solvents, strong acids or toxic catalysts. Reaction times down to <10 min without decrease in yield could be achieved through adding acetic acid as promoter, even for highly apolar biquinoxalines (yield >90 % in all cases). Moreover, it was shown that HTS has high compatibility: (i) hydrochlorides, a standard commercial form of amines, could be used directly as combined amine source and acidic catalyst, and (ii) Boc-diprotected o-PDA could be directly employed as substrate that underwent HT deprotection. A systematic large-scale computational comparison of all reported syntheses of the presented quinoxalines from the same starting compounds showed that this method is more environmentally friendly and less toxic than all existing methods and revealed generic synthetic routes for improving reaction yields. Finally, the application of the synthesized compounds as fluorescent dyes for cell staining was explored.

Novel Synthetic Routes to Prepare Biologically Active Quinoxalines and Their Derivatives: A Synthetic Review for the Last Two Decades

Quinoxalines, a class of N-heterocyclic compounds, are important biological agents, and a significant amount of research activity has been directed towards this class. They have several prominent pharmacological effects like antifungal, antibacterial, antiviral, and antimicrobial. Quinoxaline derivatives have diverse therapeutic uses and have become the crucial component in drugs used to treat cancerous cells, AIDS, plant viruses, schizophrenia, certifying them a great future in medicinal chemistry. Due to the current pandemic situation caused by SARS-COVID 19, it has become essential to synthesize drugs to combat deadly pathogens (bacteria, fungi, viruses) for now and near future. Since quinoxalines is an essential moiety to treat infectious diseases, numerous synthetic routes have been developed by researchers, with a prime focus on green chemistry and cost-effective methods. This review paper highlights the various synthetic routes to prepare quinoxaline and its derivatives, covering the literature for the last two decades. A total of 31 schemes have been explained using the green chemistry approach, cost-effective methods, and quinoxaline derivatives' therapeutic uses.

A Green, Scalable, and Catalyst-Free One-Minute Synthesis of Quinoxalines

A highly efficient and catalyst-free protocol is reported for the synthesis of quinoxalines via the classical cyclocondensation reaction between aryldiamines and dicarbonyl compounds. Remarkably simple and green reaction conditions employing methanol as solvent afforded medium to excellent yield of quinoxalines after only one-minute reaction time at ambient temperature. The conditions allow at least 10 gram scale synthesis of quinoxalines and should be a preferred starting point for optimization and method of choice for applications in the synthetic community.

Synthesis, crystal structures and Hirshfeld surface analysis of 1,4-dibenzyl-6-methyl-1,4-di-hydro-quinoxaline-2,3-dione

The title quinoxaline mol-ecule, C23H20N2O2, is not planar, the dihedral angle angle between the mean planes of the benzene rings being 72.54 (15)°. In the crystal, mol-ecules are connected into chains extending parallel to (10) by weak C-H⋯O hydrogen bonds. Weak C-H⋯π inter-actions link the chains, forming a three-dimensional network structure. Hirshfeld surface analysis revealed that the most important contributions for the crystal packing are from H⋯H (48.7%), H⋯C/C⋯H (32.0%), H⋯O/O⋯H (15.4%), C⋯C (1.9%), H⋯N/N⋯H (1.1%) contacts.

Quinoxaline Derivatives as Antiviral Agents: A Systematic Review

Background: In recent decades, several viruses have jumped from animals to humans, triggering sizable outbreaks. The current unprecedent outbreak SARS-COV-2 is prompting a search for new cost-effective therapies to combat this deadly pathogen. Suitably functionalized polysubstituted quinoxalines show very interesting biological properties (antiviral, anticancer, and antileishmanial), ensuring them a bright future in medicinal chemistry. Objectives: Focusing on the promising development of new quinoxaline derivatives as antiviral drugs, this review forms part of our program on the anti-infectious activity of quinoxaline derivatives. Methods: Study compiles and discusses recently published studies concerning the therapeutic potential of the antiviral activity of quinoxaline derivatives, covering the literature between 2010 and 2020. Results: A final total of 20 studies included in this review. Conclusions: This review points to a growing interest in the development of compounds bearing a quinoxaline moiety for antiviral treatment. This promising moiety with different molecular targets warrants further investigation, which may well yield even more encouraging results regarding this scaffold.

Eco-friendly approach to access of quinoxaline derivatives using nanostructured pyrophosphate Na2PdP2O7 as a new, efficient and reusable heterogeneous catalyst

In the present study, we report the synthesis of various quinoxaline derivatives from direct condensation of substituted aromatic 1,2-diamine with 1,2-dicarbonyl catalyzed by nanostructured pyrophosphate Na₂PdP₂O₇ as a new highly efficient bifunctionalheterogeneous catalyst. The quinoxaline synthesis was performed in ethanol as a green and suitable solvent at ambient temperature to afford the desired quinoxalines with good to excellent yields in shorter reaction times. Many Quinoxaline derivatives were successfully synthesized using various 1,2-diketones and 1,2-diamines at room temperature. Catalyst reusability showed that the Na₂PdP₂O₇ catalyst exhibited excellent recyclability without significant loss in its catalytic activity after five consecutive cycles.

Antitumoral activity of quinoxaline derivatives: A systematic review

Cancer is a leading cause of death and a major health problem worldwide. While many effective anticancer agents are available, the majority of drugs currently on the market are not specific, raising issues like the common side effects of chemotherapy. However, recent research hold promise for the development of more efficient and safer anticancer drugs. Quinoxaline and its derivatives are becoming recognized as a novel class of chemotherapeutic agents with activity against different tumors. The present review compiles and discusses studies concerning the therapeutic potential of the anticancer activity of quinoxaline derivatives, covering articles published between July 2013 and July 2018.

An insight into medicinal chemistry of anticancer quinoxalines

Quinoxalines are benzopyrazines containing benzene and pyrazine rings fused together. In the recent past, quinoxalines have attracted Medicinal Chemists considerably for their syntheses and chemistry due to their distinct pharmacological activities. Diverse synthetic protocols have been developed via multicomponent reactions, single pot synthesis and combinatorial approach using efficient catalysts, reagents, and nano-composites etc. Further, the versatility of the quinoxaline core and its reasonable chemical simplicity devise it extremely promising source of bioactive compounds. Therefore, a wide variety of bioactive quinoxalines has been realised as antitumour, antifungal, anti-inflammatory, antimicrobial, and antiviral agents. Already, a few of them are clinical drugs while many more are under various phases of clinical trials. Present review focuses on chemistry and pharmacology (both efficacy and safety) of quinoxalines and also provides some insight in to their structure-activity relationship.

Quinoxaline: An insight into the recent pharmacological advances

Quinoxaline, a fused heterocycle of benzene and pyrazine rings has gained considerable attention in the field of contemporary medicinal chemistry. The moiety is of substantial importance because of its wide array of pharmacological activities viz. anti-cancer, antimalarial, anti-inflammatory, antimicrobial, anti-HIV etc. Diversely substituted quinoxalines are important therapeutic agents in the pharmaceutical industry. This review focusses on the quinoxaline derivatives developed during the last decennial period and their biomedical applications. A compilation of patents on quinoxaline is also included herein.

1,4-Dibenzyl-6-chloroquinoxaline-2,3(1H,4H)-dione

The title compound, C22H17ClN2O2, crystallizes with two independent molecules (AandB) in the asymmetric unit. The 6-chloroquinoxaline-2,3(1H,4H)-dione ring system is essentially planar. The dihedral angles between the mean planes of the 6-chloroquinoxaline-2,3(1H,4H)-dione ring and the phenyl rings of the benzyl substituents in the two molecules are 68.34 and 73.8 (7)° forA, and 73.8 (5) and 80.7 (1)° forB, so that these rings point away from the quinoxaline ring system. In the crystal, weak C—H...O hydrogen bonds and π–π stacking interactions link the molecules into a three-dimensional network.

Benzodiazines: recent synthetic advances

This review provides a comprehensive overview of the recent developments in synthetic strategies for benzodiazines, important scaffolds in medicinal chemistry.

Quinoxaline-Based Scaffolds Targeting Tyrosine Kinases and Their Potential Anticancer Activity

Quinoxaline derivatives, also called benzopyrazines, are an important class of heterocyclic compounds. Quinoxalines have drawn great attention due to their wide spectrum of biological activities. They are considered as an important basis for anticancer drugs due to their potential activity as protein kinase inhibitors. In this review, we focus on the chemistry of the quinoxaline derivatives, the strategies for their synthesis, their potential activities against various tyrosine kinases, and on the structure-activity relationship studies reported to date.

One-step approach for the synthesis of functionalized quinoxalines mediated by T3P®–DMSO or T3P® via a tandem oxidation–condensation or condensation reaction

An easy and efficient (T3P®)–DMSO or T3P® mediated oxidation–condensation or condensation reaction for the synthesis of quinoxalines from the different arrays of condensing partners and ortho-phenylene diamines (o-PDs) in one step has been reported.

An Efficient and Recyclable Nanoparticle-Supported Cobalt Catalyst for Quinoxaline Synthesis

The syntheses of quinoxalines derived from 1,2-diamine and 1,2-dicarbonyl compounds under mild reaction conditions was carried out using a nanoparticle-supported cobalt catalyst. The supported nanocatalyst exhibited excellent activity and stability and it could be reused for at least ten times without any loss of activity. No cobalt contamination could be detected in the products by AAS measurements, pointing to the excellent activity and stability of the Co nanomaterial.