Potent quinoxaline-based inhibitors of PDGF receptor tyrosine kinase activity. Part 2: the synthesis and biological activities of RPR127963 an orally bioavailable inhibitor

AlCl3-Promoted Intramolecular Indolinone-Quinolone Rearrangement of Spiro[indoline-3,2'-quinoxaline]-2,3'-diones: Easy Access to Quinolino[3,4-b]quinoxalin-6-ones

A facile and direct intramolecular indolinone-quinolone rearrangement was developed for the synthesis of quinolino[3,4-b]quinoxalin-6-ones from spiro[indoline-3,2'-quinoxaline]-2,3'-diones, which are readily available with use of isatines, malononitrile, and 1,2-phenylenediamines under quite mild conditions. This efficient approach provides excellent yields and could potentially be used for the construction of a diverse library of quinolino[3,4-b]quinoxalin-6-ones for high-throughput screening in medicinal chemistry. The reaction mechanism is explored by extensive DFT calculations.

A new triazolyl-indolo-quinoxaline induces apoptosis in gastric cancer cells by abrogating the STAT3/5 pathway through upregulation of PTPεC

Signal transducer and activator of transcription 3 (STAT3) and STAT5 are the transcription factors that have been studied extensively in relevance to the development of cancers in humans. Suppression of either STAT3 or STAT5-mediated signaling events has been demonstrated to be effective in inducing cytotoxicity in cancer cells. Herein, new hybrids of triazolyl-indolo-quinoxaline are synthesized and examined for their effect on the activation of STAT3 and STAT5 pathways in gastric cancer (GC) cells. Among the newly synthesized compounds, 2,3-difluoro-6-((1-(3-fluorophenyl)-1H-1,2,3-triazol-5-yl)methyl)-6H-indolo[2,3-b]quinoxaline (DTI) displayed selective cytotoxicity against GC cells over their normal counterpart. Flow cytometric analysis, annexin-V-fluorescein isothiocyanate staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, live and dead assay, and caspase activation experiments suggested DTI as a potent inducer of apoptosis. The mechanistic approach revealed that DTI imparts cytotoxicity via downregulating the phosphorylation of STAT3Y705 and STAT5Y694/699 . DTI significantly reduced the nuclear pool of STAT3/STAT5 and reduced the DNA interaction ability of STAT3/STAT5 as evidenced by immunofluorescence and electrophoretic mobility shift assay. Further investigation revealed that inhibitory effects towards STAT proteins were mediated through the suppression of upstream kinases such as JAK1, JAK2, and Src. Treatment of GC cells with pervanadate counteracted the DTI-driven STAT3/STAT5 inhibition suggesting the involvement of tyrosine phosphatase. Upon DTI exposure, there was a significant upregulation in the mRNA and protein expression of PTPεC, which is a negative regulator of the JAK-STAT pathway. Knockdown of PTPεC suppressed the DTI-induced STATs inhibition in GC cells. Taken together, triazolyl-indolo-quinoxaline is presented as a new inhibitor of the STAT3/STAT5 pathway in GC cells.

Divergent Synthesis of 3-(Indol-2-yl)quinoxalin-2-ones and 4-(Benzimidazol-2-yl)-3-methyl(aryl)cinnolines via Polyphosphoric Acid (PPA)-Mediated Intramolecular Rearrangements of 3-(Methyl/aryl(2-phenylhydrazono)methyl)quinoxalin-2-ones

Herein, we report a polyphosphoric acid (PPA)-mediated divergent metal-free operation to access a diverse collection of 3-(indol-2-yl)quinoxalin-2-ones and 4-(benzimidazol-2-yl)-3-methylcinnolines in moderate to excellent overall yields. The described process involves two distinct, and competing rearrangements of 3-(methyl(2-phenylhydrazono)methyl)quinoxalin-2-ones, namely [3,3]-sigmatropic Fischer rearrangement with the formation of an indole ring to produce 3-(indol-2-yl)-quinoxalin-2-ones, and Mamedov rearrangement with simultaneous construction of benzimidazole and cinnoline rings to form the new biheterocyclic system─4-(benzimidazol-2-yl)-3-methylcinnolines. The reaction mechanism of both rearrangement channels is explored by extensive dispersion-corrected DFT calculations. It is partcularly remarkable that when 3-(aryl(2-phenylhydrazono)methyl)quinoxalin-2-ones is used, instead of 3-(methyl(2-phenylhydrazono)methyl)quinoxalin-2-ones, reactions proceed regioselectively with the formation of only rearrangement products─4-(benzimidazol-2-yl)-3-arylcinnolines with high yields. This operationally simple protocol enables a rapid access to these scaffolds and is compatible with a wide scope of starting materials. In addition, the new rearrangement found features a promising approach for the design of unique compound libraries for drug design and discovery programs.

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.

Synthesis of 2-styryl-quinazoline and 3-styryl-quinoxaline based sulfonate esters via sp3 C-H activation and their evaluation for α-glucosidase inhibition

Synthesis of 2-styryl-quinazolines and 3-styryl-quinoxaline based sulfonates is reported via sp3 C-H functionalization in the presence of triethylamine (10 mol%). The resulting compounds were tested for the α-glucosidase enzyme inhibition...

Acenaphtoquinoxaline as a selective fluorescent sensor for Hg (II) detection: experimental and theoretical studies

A new fluorescent chemosensor based on quinoxaline was successfully synthesized through a facile and green catalytic reaction of ortho-phenylenediamine (O-PDA) and acenaphthylene-1,2-dione in the presence of SBA-Pr-SO3H. Prepared a "switch-off" quinoxaline-based receptor to recognized Hg2+ ion in high selectively and, without any interference from other metal ions, was developed. The photophysical behavior of this fluorophore was studied in acetonitrile by using fluorescence spectra. The fluorescence properties of several cations to acenaphtoquinoxaline were investigated in acetonitrile, and the competition test displayed that the probe fluorescence changes were specific for Hg2+ ion. The obtained results have shown high selectivity and sensitivity only for Hg2+. Also, the detection limit was as low as 42 ppb, and a top linear trend was observed between the concentration of Hg2+ ions and fluorescence intensity. The binding stoichiometry between chemosensor L and Hg2+ was found to be 1:1. Moreover, a computational study was performed to obtain an electronic description of the fluorescence emission and quenching mechanisms. The optimized structures and binding mechanisms were supported with a high correlation and agreement by spectroscopy and DFT calculations.

Highly Efficient Ultrasound Promoted Synthesis of 2-phenylquinoxaline in Glycerol- Water

INTRODUCTION

Quinoxalines show diversified applications in the field of medicinal chemistry.

MATERIALS AND METHODS

Therefore, we have designed a highly efficient, environmentally benign and one-pot protocol for the synthesis of 2-phenylquinoxaline from the reaction of Acetophenone, N-bromosuccinimide and 1,2-phenylenediamine under ultrasound irradiation in glycerol-water.

RESULTS AND DISCUSSION

We observed that, although the reaction efficiently completed in all of these solvents, the use of glycerol-water with different ratios gives consistently higher yields (89-94%) and decreases reaction times.

CONCLUSION

The main advantages of this protocol are that it is a green method, avoids the use of toxic catalysts and volatile organic medium and the product is obtained with excellent yield.

Construction of hybrid polycyclic quinolinobenzo[a]phenazinone architectures using solid-state melt reaction (SSMR)

An efficient and versatile protocol for the synthesis of hybrid polycyclic quinolinobenzo[a]phenazinones has been developed under SSMR condition via intramolecular domino Knoevenagel-hetero-Diels-Alder reaction involving the generation of two new six membered fused rings and three contiguous stereogenic centers.

Ethyl 6′-cyano-7′-(p-tolyl)-1′,6′,7′,7a′-tetrahydro-3′H-spiro[indeno[1,2-b]quinoxaline-11,5′-pyrrolo[1,2-c]thiazole]-6′-carboxylate

The title compound, C31H26N4O2S, crystallizes in a triclinic centrosymmetric lattice with two molecules in the unit cell. The five-membered thiazole and pyrrolidine rings adopt twisted and envelope conformations, respectively. The methoxyphenyl and indenoquinoxaline planes are oriented with a dihedral angle of 88.1 (1)° to each other. The crystal structure features C—H...N, C—H...O and C—H...S intermolecular interactions forming two R 2 2(16) ring motifs and a C(11) and two C 2 2(14) chain motifs. The –CH3 group of the ethyl side chain is disordered over two positions with site occupancies of 0.55 and 0.45.

Luminescent bis(benzo[d]thiazolyl)quinoxaline: facile synthesis, nucleic acid and protein BSA interaction, live-cell imaging, biopharmaceutical research and cancer theranostic application

A series of quinoxaline-2-hydroxyphenylbenzothiazole scaffolds were synthesized and characterized using NMR, UV, fluorescence spectroscopy and LCMS. These newly synthesized compounds were found to be cytotoxic in human epithelioid cervix carcinoma (HeLa) and human colon cancer cell lines (Caco-2). Selectivity of the compounds 7e and 7g are more than 9 fold higher in Caco-2 cells with respect to the normal cell line HEK-293. The most fluorescent compound 7e has displayed high cytoselectivity, significant cellular uptake in HeLa cells and strong binding efficacy with DNA and BSA. The most potent compound 7g has primarily classified as BCS class 4 and BDDCS class 4.

A series of luminescent bis(benzo[d]thiazolyl)quinoxalines have been synthesized and their fluorescence properties, anticancer potency, DNA and BSA interactions, cellular uptake, and metabolic stabilities are investigated.

A highly diastereoselective [5+1] annulation to 2,2,3-trisubstituted tetrahydroquinoxalines via intramolecular Mannich-type trapping of ammonium ylides

A highly diastereoselective [5+1] annulation to 2,2,3-trisubstituted tetrahydroquinoxalines was developed by us.

PIDA-mediated intramolecular oxidative C–N bond formation for the direct synthesis of quinoxalines from enaminones

A intramolecular oxidative C(sp²)–N bond formation mediated by hypervalent iodine(iii) to obtain quinoxalines from readily available N-(2-acetaminophenyl)enaminones was developed. A tandem process involving PIDA-mediated intramolecular condensation cyclization and a subsequent elimination was postulated, which was highly efficient and metal-free under mild conditions. Moreover, flexible structural modifications of quinoxalines bearing carbonyl groups are of interest for further transformations as building blocks in organic synthesis.

An expedient hypervalent iodine(iii)-mediated approach to obtain substituted quinoxalines from readily available enaminones has been developed under mild conditions.

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.

6′-(3-Bromophenyl)-7′-nitro-1′,6′,7′,7a'-tetrahydro-3′H-spiro[indeno[1,2-b]quinoxaline-11,5′-pyrrolo[1,2-c]thiazole]

The title compound, C26H19BrN4O2S, crystallizes in a monoclinicC-centred lattice with eight molecules in the unit cell. The five-membered thiazole and pyrrolidine rings adopt envelope conformations and the bromophenyl and indenoquinoxaline planes are oriented at a dihedral angle of 61.6 (1)° to each other. The molecular structure features an intramolecular C—H...N interaction leading to anS(6) ring motif.C(9) andC(10) chains along thec- andb-axis directions form through C—H...Br and C—H...S contacts, respectively. In addition, C—H...O and C—H...N hydrogen bonds form inversion dimers withR22(10) andR22(14) motifs, respectively. One O atom is disordered over two positions (occupancy ratio 0.63:0.37).

7′-Nitro-6′-phenyl-1′,6′,7′,7a′-tetrahydro-spiro[indeno[1,2-b]quinoxaline-11,5′-pyrrolo[1,2-c][1,3]thiazole]

In the title compound, C26H20N4O2S, the thiazole and pyrrolidine rings adopt envelope conformations with the respective flap atoms being the N atom and the nitro-bearing C atom. The phenyl and indenoquinoxaline planes are oriented at an angle of 66.72 (1)° to each other. The molecular structure features two intramolecular interactions,viz. C—H...N and C—H...O. In the crystal, the molecules are connected through C—H...N and C—H...O interactions, forming ring motifs [twoR21(7),R22(14),R22(22) andR22(16)]. These ring motifs are connected through aC(9) motif chain.

Efficient synthesis of novel 1,2,3-triazole-linked quinoxaline scaffold via copper-catalyzed click reactions

New 1,2,3-triazoles-linked quinoxaline, were prepared by the reaction of 2-chloro-3-(prop-2-ynyloxy)quinoxaline or 2,3-bis(prop-2-ynyloxy)quinoxaline with aromatic azides via copper-catalyzed click reactions in the presence of the Schiff base ligands.

SO3H-functionalized metal organic frameworks: an efficient heterogeneous catalyst for the synthesis of quinoxaline and derivatives

The high dispersed –SO₃H groups in the framework of MIL-101-Cr–NH–RSO₃H ensure high catalytic activity for the condensation of 1,2-diamines with benzil. The catalyst exhibits good stability, general applicability and excellent recycling performance.

Hypervalent iodine(iii)-promoted N-incorporation into N-aryl vinylogous carbamates to quinoxaline diesters: access to 1,4,5,8-tetraazaphenanthrene

An oxidative N-incorporation strategy for synthesis of quinoxaline diesters under metal-free and mild reaction conditions is described via the formation of two C(sp²)–N bonds utilizing NaN₃ as the cheap N-atom source.

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.

Crystal structure of ethyl (2S,2′R)-1′-benzyl-3-oxo-3H-dispiro[1-benzothiophene-2,3′-pyrrolidine-2′,11′′-indeno[1,2-b]quinoxaline]-4′-carboxylate

In the title compound, C₃₅H₂₇N₃O₃S, the spiro-linked five-membered rings both adopt twisted conformations. The pyrrolidine ring makes dihedral angles of 80.5 (1) and 77.4 (9)° with the benzo­thio­phene ring system and the quinoxaline ring system, respectively. The S atom and C=O unit of the benzo­thio­phene ring system are disordered over two opposite orientations in a 0.768 (4):0.232 (4) ratio. The atoms of the ethyl side chain are disordered over two sets of sites in a 0.680 (16):0.320 (16) ratio. In the crystal, mol­ecules are linked by C—H⋯O, C—H⋯N and π–π inter­actions [shortest centroid–centroid distance = 3.4145 (19) Å], resulting in a three-dimensional network.