An efficient iodine–DMSO catalyzed synthesis of quinoxaline derivatives

I2/DMSO-mediated oxidative C-C and C-heteroatom bond formation: a sustainable approach to chemical synthesis

The I2/DMSO pair has emerged as a versatile, efficient, practical, and eco-friendly catalyst system, playing a significant role as a mild oxidative system, and thus employed as a good alternative to metal catalysts in synthetic chemistry. Presently, I2/DMSO is a thriving catalytic system that is used in preparing C-C and C-X (X = O/S/N/Se/Cl/Br) bonds, resulting in the formation of various bioactive molecules. Many processes utilize this system, including in situ glyoxal synthesis by diverse sp, sp2, and sp3 functionalities via iodination and subsequent Kornblum oxidation. Focusing on oxidation processes, this study examines the synergistic effect of dimethyl sulfoxide (DMSO) and molecular iodine in improving synthetic techniques. We provide a comprehensive overview of the research progress on the I2/DMSO catalytic system for the formation of C-C and C-heteroatom bonds from 2018 to the present. Additionally, the future prospects of this research field are discussed.

Recent Methods for the Synthesis of Quinoxaline Derivatives and their Biological Activities

Quinoxaline derivatives have been incorporated into numerous marketed drugs used for the treatment of various diseases. Examples include glecaprevir (Mavyret), voxilaprevir (Vosevi), Balversa (L01EX16) (erdafitinib), carbadox, XK469R (NSC698215), and becampanel (AMP397). These quinoxaline derivatives exhibit a diverse range of pharmacological activities, including antibacterial, antitubercular, antiviral, anti-HIV, anti-inflammatory, antifungal, anticancer, antiproliferative, antitumor, kinase inhibition, antimicrobial, antioxidant, and analgesic effects. Recognizing the significance of these bioactive quinoxaline derivatives, researchers have dedicated their efforts to developing various synthetic methods for their production. This review aimed to compile the most recent findings on the synthesis and biological properties of quinoxaline derivatives from 2015 to 2023.

Recent Advances of Green Catalytic System I2/DMSO in C–C and C–Heteroatom Bonds Formation

Developing a green, practical and efficient method for the formation of C–C and C–Heteroatom bonds is an important topic in modern organic synthetic chemistry. In recent years, the I2/DMSO catalytic system has attracted wide attention because of its green, high efficiency, atomic economy, low cost, mild reaction conditions and it is environment-friendly, which is more in line with the requirements of sustainable chemistry. Heteroatom-containing compounds have shown lots of important applications in pharmaceutical synthesis, agrochemicals, material chemistry and organic dyes. At present, the I2/DMSO catalytic system has been successfully applied to the synthesis of various heteroatom-containing compounds. The C–C and C–Heteroatom bonds have been formed efficiently, which has been proved to be a green and mild catalytic system. In this review, the research achievements of the I2/DMSO catalytic system in the formation of C–C and C–Heteroatom bonds from 2015 to date are described, and the research area is prospected. This review attempts to reveal the general law of iodine catalysis and lay a foundation for the design of new reactions.

Pyridine-2-yl Quinoxaline (2-CPQ) Derivative As a Novel Pink Fluorophore: Synthesis, and Chemiluminescence Characteristics

Quinoxaline derivatives are well-known N-heterocycles with pharmacological and fluorescence activities. Almost all quinoxaline derivatives with extensive π-conjugation have been introduced as fluorophores which emit blue and green light. For the first time, we designed and synthesized 6-chloro-2,3 di(Pyridine-2yl) quinoxaline (2-CPQ) as a pink fluorophore in acetonitrile medium by simple route at room temperature whitin 30 min. The synthesized quinoxaline was identified using ¹H, ¹³C NMR, MS, and FT-IR spectroscopy. Our results showed that the iodine-catalyzed method for both oxidation and cyclization during the synthesis of quinoxaline from pyridine 2-carbaldehyde was straightforward, efficient, and clean. All of the mentioned characterization devices confirmed the synthesis of 2-CPQ.Moreover, we studied the photophysical properties of the synthesized fluorophore in which The UV-Vis absorption spectrum of 2-CPQ in DMF were three peaks at 451, 518 and 556 nm. Based on photophysical properties investigation, 2-CPQ shows good fluorescence with maximum peaks 607 and 653 nm in DMF as solvent (ф_F = 0.21). Hence, the fluorophore was applied in the peroxyoxalate chemiluminescence system. The reaction of imidazole, H₂O_2, and bis (2,4,6-trichlorophenyl) oxalate (TCPO) can transfer energy to a 6-chloro-2,3 di(pyridine-2yl) quinoxaline. In this process, dioxetane was synthesized, which chemically initiated the electron exchange luminescence (CIEEL) mechanism and led to pink light emission. We anticipate our synthesized fluorophores 2-CPQ will have great potential applications in imaging and medical markers.

Recent advances in the transition-metal-free synthesis of quinoxalines

Quinoxalines, also known as benzo[a]pyrazines, constitute an important class of nitrogen-containing heterocyclic compounds as a result of their widespread prevalence in natural products, biologically active synthetic drug candidates, and optoelectronic materials. Owing to their importance and chemists' ever-increasing imagination of new transformations of these products, tremendous efforts have been dedicated to finding more efficient approaches toward the synthesis of quinoxaline rings. The last decades have witnessed a marvellous outburst in modifying organic synthetic methods to create them sustainable for the betterment of our environment. The exploitation of transition-metal-free catalysis in organic synthesis leads to a new frontier to access biologically active heterocycles and provides an alternative method from the perspective of green and sustainable chemistry. Despite notable developments achieved in transition-metal catalyzed synthesis, the high cost involved in the preparation of the catalyst, toxicity, and difficulty in removing it from the final products constitute disadvantageous effects on the atom economy and eco-friendly nature of the transformation. In this review article, we have summarized the recent progress achieved in the synthesis of quinoxalines under transition-metal-free conditions and cover the reports from 2015 to date. This aspect is presented alongside the mechanistic rationalization and limitations of the reaction methodologies. The scopes of future developments are also highlighted.

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.

I2/DMSO-catalyzed one-pot approach for the synthesis of 1,3,4-selenadiazoles

A three-component cascade reaction for the synthesis of 1,3,4-selenadiazoles and their derivatives from arylaldehydes, hydrazine, and elemental selenium by using molecular iodine is reported. This strategy is operationally simple, well-suited to a wide range of functional groups, and provides the desired products in moderate to excellent yields. The proposed mechanism predicts that the reaction tolerated a radical process.

An iodine/DMSO-catalyzed sequential one-pot approach to 2,4,5-trisubstituted-1H-imidazoles from α-methylene ketones

A sequential one-pot approach to 2,4,5-trisubstituted imidazoles has been developed from α-methylene ketones and aldehydes. This methodology employs air-moisture stable reaction conditions and an inexpensive iodine/DMSO system affording a diverse range of known and novel (substrate scope) 2,4,5-trisubstituted imidazoles in moderate to excellent yields. The iodine/DMSO system was extended to the domino convergent synthesis of two functionalized intermediates, benzil and benzaldehyde, to produce the final product.

Iodine/DMSO oxidations: a contemporary paradigm in C–N bond chemistry

A new era in the organic synthetic world is demanding greener protocols for the execution of reactions.