Studies on Compounds related to Pyrazine. III. Synthesis of 2-Substituted Thiazolo [b] quinoxaline.

Saikachi, Haruo; Tagami, Shoichiro

doi:10.1248/cpb.9.941

Cited by 22 publications

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“…Quinoxalineaminothiol (QAT), the preferred starting material for the synthesis of QDTA 7, is potentially accessible by a number of routes (Scheme 1) (19). The first involves the conversion of dichloroquinoxaline QCl 2 to the corresponding aminochloro derivative QACl, followed by thiation of the latter with sodium sulfide.…”

Section: Synthesismentioning

confidence: 99%

Quinoxaline-1,2,3-dithiazolyls Synthesis, EPR characterization, and redox chemistry

Cordes¹,

Mingie²,

Oakley³

et al. 2001

Can. J. Chem.

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Oxidation of quinoxalineaminothiol with SCl2 or S2Cl2/Cl2 affords a series of compounds based on the quinoxaline-1,2,3-dithiazole framework QDTA. Under highly oxidizing conditions, the 1,2,3-dithiazolyl ring is opened to afford the acyclic dichlorosulfimino-sulfenyl chlorides Clx-QDTA-Cl3 (x = 0, 1, 2). Reduction of these "trichloro" compounds leads to ring closure. For x = 2, reduction using S2Cl2 affords the dithiazolylium chloride [Cl2-QDTA][Cl]. For all values of x, reduction with iodide ion (3 mol equiv) affords the corresponding dithiazolyl radical [Clx-QDTA]. The radicals can be isolated in good yield in crude form, but attempts to purify them by vacuum sublimation lead to thermal degradation. The radicals have nonetheless been fully characterized by EPR spectroscopy, and the assignments of the observed hyperfine coupling constants cross-matched with those obtained by computation at the B3LYP/6-31G** level. The structures of the trichloro compounds Clx-QDTA-Cl3 (x = 1, 2) have been confirmed by X-ray crystallography. Crystal data: Cl-QDTA-Cl3, monoclinic, space group C2/c, a = 30.561(5) Å, b = 4.9764(9) Å, c = 22.247(4) Å, β = 131.822(14)°, V = 2521.4(8) Å3, Z = 8, R(F) = 0.043, and Rw(F) [I [Formula: see text] σ (I)] = 0.049; Cl2-QDTA-Cl3, orthorhombic, space group Pnma, a = 18.627(12) Å, b = 6.848(4) Å, c = 10.926(7) Å, V = 1393.7(15) Å3, Z = 4, R(F) = 0.047, and Rw(F) [I [Formula: see text] 3σ(I)] = 0.060.Key words: thiazyl radicals, molecular conductors, EPR spectroscopy, quinoxaline, DFT calculations.

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Section: Synthesismentioning

confidence: 99%

Quinoxaline-1,2,3-dithiazolyls Synthesis, EPR characterization, and redox chemistry

Cordes¹,

Mingie²,

Oakley³

et al. 2001

Can. J. Chem.

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“…3‐Chloroquinoxalin‐2( 1H )‐one 8, 3‐aminoquinoxalin‐ 2( 1H )‐one 9, 3‐chloroquinoxalin‐2‐amine 10a, and quinoxaline‐2,3‐diamine 10b were prepared as reported. Furthermore, solvent free reaction of compounds 10a,b with ethylcyanoacetate produced the corresponding cyanoacetamide derivatives 11a,b .…”

Section: Resultsmentioning

confidence: 99%

Exploration of quinoxaline derivatives as antimicrobial and anticancer agents

Bayoumi

Ghiaty

El‐Gilil

et al. 2019

Journal of Heterocyclic Chem

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Novel 2 and 3‐substituted quinoxaline derivatives were synthesized through various synthetic pathways, among which cyanoacetamide and cyanoacetohydrazide quinoxaline derivatives 4a‐c and 11a‐c, respectively, were synthesized. Furthermore, methoxy quinoxaline derivatives 3c and quinoxaline derivatives bearing substituted pyridines 6a,b, 12a,b, and 13a,b were designed to be synthesized. However, we have synthesized acrylohydrazide 5a,b and 7/acrylamide derivatives, Schiff base analogues 14a‐f, pyrazole derivatives 15a‐e, amide derivatives 16a‐f, guanidine derivatives 16 g,h as well as, quinoxalin‐2‐methylallyl propionate derivative 14g. All the synthesized compounds were confirmed via spectral data and elemental analyses. Moreover, the newly synthesized compounds were evaluated for their antimicrobial activity (Gm +ve, Gm −ve in comparison to Gentamycin a standard) and fungi (in comparison to Ketoconazole as a standard). Thus, compound 16b showed promising antimicrobial activity against B. subtilis, P. vulgaris, and S. mutants with values ranging from 20 to 27‐mm zone of inhibition. While compounds 5a, 14e,f, and 16a,c,d,g,h showed potent antimicrobial activity. Moreover, the National Cancer Institute (NCI) selected 20 compounds that were submitted for anticancer screening against 60 types of cancer cell lines. The most active compounds are 5b and 12a where compound 5b containing 2,4‐dichlorophenyl moiety at cyanoacetamide linkage of hydrazine quinoxaline backbone exerted significant growth inhibition activity against Leukemia MOLT‐4, Renal cancer UO‐31, and Breast cancer MCF‐7. In addition, compound 12a having 4,6‐diaminopyridinone side chain at position‐3 of quinoxaline nucleus exhibited remarkable anticancer activity against renal cancer UO‐31.

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“…Further evidence for the assigned structure 3 and in turn the proposed reaction pathway leading to it (Scheme 1) is supported by an alternate synthesis of 3Ea. Thus, reaction of 1,5-diphenyl-3-mercaptoformazan 9Ea, commonly known as dithiazone, with either 2,3-dichloroquinoxaline 7 17 or 2-amino-3-chloroquinoxaline 8 18 To account for the formation of 3 via the reaction of 1 with 2, it is suggested, as depicted in Scheme 1, that the reactions started with the formation of the respective thiohydrazonate esters I as intermediates which in turn undergo in situ deaminative cyclization to give the respective 3. The first step is analogous to the formation of thiohydrazonates by reaction of hydrazonoyl halides with thiols.…”

Section: Resultsmentioning

confidence: 99%

Site Selectivity in Reactions of Hydrazonoyl Halides With 2-Amino-3-quinoxalinethiol: A New General Access to Functionalized 4H-1,3,4-Thiadiazino-[5,6-b]quinoxalines

Shawali

Mosselhi

Farghaly

2005

Phosphorus, Sulfur, and Silicon and the Related Elements

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Studies on Compounds related to Pyrazine. III. Synthesis of 2-Substituted Thiazolo [b] quinoxaline.

Cited by 22 publications

References 0 publications

Quinoxaline-1,2,3-dithiazolyls Synthesis, EPR characterization, and redox chemistry

Quinoxaline-1,2,3-dithiazolyls Synthesis, EPR characterization, and redox chemistry

Exploration of quinoxaline derivatives as antimicrobial and anticancer agents

Site Selectivity in Reactions of Hydrazonoyl Halides With 2-Amino-3-quinoxalinethiol: A New General Access to Functionalized 4H-1,3,4-Thiadiazino-[5,6-b]quinoxalines

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Studies on Compounds related to Pyrazine. III. Synthesis of 2-Substituted Thiazolo [b] quinoxaline.

Cited by 22 publications

References 0 publications

Quinoxaline-1,2,3-dithiazolyls  Synthesis, EPR characterization, and redox chemistry

Quinoxaline-1,2,3-dithiazolyls  Synthesis, EPR characterization, and redox chemistry

Exploration of quinoxaline derivatives as antimicrobial and anticancer agents

Site Selectivity in Reactions of Hydrazonoyl Halides With 2-Amino-3-quinoxalinethiol: A New General Access to Functionalized 4H-1,3,4-Thiadiazino-[5,6-b]quinoxalines

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Quinoxaline-1,2,3-dithiazolyls Synthesis, EPR characterization, and redox chemistry

Quinoxaline-1,2,3-dithiazolyls Synthesis, EPR characterization, and redox chemistry