Tag: M.W=100-150

Senger, Johanna published the artcileSynthesis and Biological Investigation of Oxazole Hydroxamates as Highly Selective Histone Deacetylase 6 (HDAC6) Inhibitors, Category: pyrazines, the publication is Journal of Medicinal Chemistry (2016), 59(4), 1545-1555, database is CAplus and MEDLINE.

Histone deacetylase 6 (HDAC6) catalyzes the removal of an acetyl group from lysine residues of several non-histone proteins. Herein, the preparation of thiazole-, oxazole-, and oxadiazole-containing biarylhydroxamic acids by a short synthetic procedure is reported. They were identified as selective HDAC6 inhibitors by investigating the inhibition of recombinant HDAC enzymes and the protein acetylation in cells by Western blotting (tubulin vs histone acetylation). The most active compounds exhibited nanomolar potency and high selectivity for HDAC6. For example, an oxazole hydroxamate inhibits HDAC6 with an IC₅₀ of 59 nM and has a selectivity index of >200 against HDAC1 and HDAC8. This is the first report showing that the nature of a heterocycle directly connected to a zinc binding group (ZBG) can be used to modulate subtype selectivity and potency for HDAC6 inhibitors to such an extent. Compounds I (R = Br or Ph) were found to have the bect activity/HDAC6 selectivity. The high potency and selectivity of the oxazoles was rationalized by mol. modeling and docking.

Journal of Medicinal Chemistry published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C4H5F3N2O3S, Category: pyrazines.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Novacek, Libor published the artcileAntituberculotics. XII. Functional derivatives of ring-substituted pyrazinecarboxylic acids, Computed Properties of 4604-72-2, the publication is Acta Facultatis Pharmaceuticae Universitatis Comenianae (1975), 27(5), 73-87, database is CAplus.

The most active of a series of 20 ring-substituted pyrazinecarboxylic acid derivatives tested in vitro against Mycobacterium tuberculosis H37Rv, M. avium, and M. kansasii were 3-hydrazinopyrazine-2-carboxylic acid hydrazide (I) [21279-74-3], 5-bromopyrazine-2-carboxamide [36070-84-5], and 5-(vanillidenehydrazino)pyrazine-2-carboxylic acid 2-vanillidenehydrazide [36805-05-7]. For example, I was active against M. tuberculosis and M. kansasii at 25 μg/ml and against M. avium at 50 μg/ml. The acid hydrazides tested were generally more active than amides and thioamides. None of 3 of the most active compounds, tested in vivo in mice, was as potent as pyrazinamide [98-96-4].

Acta Facultatis Pharmaceuticae Universitatis Comenianae published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, Computed Properties of 4604-72-2.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Biedulska, Malgorzata published the artcileComparative solution equilibria studies of complex formation between Ir(III) ion and antituberculosis drug analogues: Spectroscopic, potentiometric and conductometric approach, SDS of cas: 4604-72-2, the publication is Journal of Molecular Liquids (2019), 111887, database is CAplus.

The detailed studies concerning the binding mode of bioactive ligands: pyrazine-2-carboxamide (PZA), pyrazine-2-thiocarboxamide (PTCA) and pyrazine-2-amidoxime (PAOX) have been performed by using three independent techniques: UV-Vis spectroscopy, potentiometry and conductometry. The composition and stability constants of new series Ir(III) complexes with antituberculosis drug and its structural analogs have been determined in aqueous and nonaqueous solutions The hypsochromic shifts of bands and appearance of new peaks during UV-Vis spectrophotometric titration confirmed the interaction of Ir(III) ion with bioligands. In the studied pH range activation of pyrazine derivatives began complexation process. The sharply changed of conductimetric curves slope clearly demonstrated that the ML₂ type complexes formation with relatively high stability are favored. Under the exptl. conditions, it was found that metal ion interact with ligands leading to the formation of pos. charged complexes. The gradual and cumulative stability constants of Ir(III) coordination compounds have been determined The stability order of Ir(III)- PY systems studied is as follows: PAOX > PZA > PTCA. The anal. of formation equilibrium revealed that mononuclear Ir(III) coordination compounds with metal to ligand molar ratio equals 1:2 are preferable with prominently high solution stability. Comparison of stability constants values showed that an increase in the efficiency of the reaction between metal ion and bioligands was observed with elongation of substituent chain. In the binary complexes, the bidentate nature of bioactive ligands and participation of amine and heterocyclic nitrogens in coordination of central ion were confirmed.

Journal of Molecular Liquids published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, SDS of cas: 4604-72-2.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Ogryzek, Malgorzata published the artcileCoordination chemistry of pyrazine derivatives analogues of PZA: design, synthesis, characterization and biological activity, Computed Properties of 4604-72-2, the publication is RSC Advances (2016), 6(57), 52009-52025, database is CAplus.

Ru(III) complexes with pyrazine derivatives: 2,3-bis(2-pyridyl)pyrazine (DPP), pyrazine-2-amidoxime (PAOX), pyrazine-2-thiocarboxamide (PTCA) and 2-amino-5-bromo-3-(methylamino)pyrazine (ABMAP) have been prepared Characterization of the compounds was acquired using UV-Vis and FT-IR spectroscopy, elemental anal., conductivity and electrochem. measurements as well as thermogravimetric studies. The ligand field parameters, Δ₀ (splitting parameter), B (Racah parameter of interelectronic repulsion) and β (nephelauxetic ratio) were calculated The stabilities of the Ru(III) complexes have also been confirmed by spectrophotometric titration methods in acetonitrile and water solutions The data showed that the examined compounds are stable both in solution and solid states, which was also confirmed by the values of their stability constants found. Moreover, the mol. structures of the complexes have been optimized using AM1 and PM3 methods and this supported octahedral geometry around the Ru(III) ion. The min. inhibitory (MIC) and min. bactericidal concentration (MBC) for synthesized complexes were studied against two Gram (+) bacteria, two Gram (-) bacteria and fungi – three reference strains of Candida albicans. The results show that [RuCl(PAOX)₂(OH₂)]Cl₂ display antifungal activity.

RSC Advances published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, Computed Properties of 4604-72-2.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Cooper, Alan B. published the artcile1-Thiazol-2-yl-N-3-methyl-1H-pyrozole-5-carboxylic acid derivatives as antitumor agents, Name: Pyrazin-2-ylboronic acid, the publication is Bioorganic & Medicinal Chemistry Letters (2017), 27(18), 4471-4477, database is CAplus and MEDLINE.

A class of substituted 1-thiazol-2-yl-N-3-methyl-1H-pyrozole-5-carboxylic acid derivatives was found to have potent anti-proliferative activity against a broad range of tumor cell lines. A compound from this class (14) was profiled across a broad panel of hematol. and solid tumor cancer cell lines demonstrating cell cycle arrest at the G0/G1 interphase and has potent anti-proliferative activity against a distinct and select set of cancer cell types with no observed effects on normal human cells. An example is the selective inhibition of human B-cell lymphoma cell line (BJAB). Compound 14 was orally bioavailable and tolerated well in mice. Synthesis and structure activity relationships (SAR) in this series of compounds are discussed.

Bioorganic & Medicinal Chemistry Letters published new progress about 762263-64-9. 762263-64-9 belongs to pyrazines, auxiliary class Pyrazine,Boronic acid and ester,Boronic Acids, name is Pyrazin-2-ylboronic acid, and the molecular formula is C4H5BN2O2, Name: Pyrazin-2-ylboronic acid.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Domzalska, Marta published the artcileSensors to the Diagnostic Assessment of Anticancer and Antimicrobial Therapies Effectiveness by Drugs a with Pyrazine Scaffold, Name: Pyrazine-2-carbothioamide, the publication is Chemosensors (2022), 10(1), 24, database is CAplus.

Treatment with pyrazine derivatives-antituberculosis pyrazinamide (PZA), anticancer bortezomib (BZM), and antifungal pyrazine-2-amidoxime (PAOX) and pyrazine-2-thiocarboxamide (PTCA)-is associated with side effects, as observed in the case of other therapeutic drugs. To prevent the side effects of pyrazine derivatives, researchers are working to develop a universal method that will detect these compounds in body fluids. There is a lack of literature data about voltammetric measurements with poly-L-amino acid-modified GCEs surfaces. The available reports describe the application of various modifications of these electrodes for the detection of different active substances of drugs; however, they do not indicate one particular method for the detection of drugs with a pyrazine skeleton. This research aimed to prepare three types of glassy carbon electrodes (GCEs) with modified surfaces by electropolymerization using 1, 10, and 100 mM solutions of L-glycine (Gly), L-alanine (Ala), L-lysine (Lys), resp. The poly-amino acid coatings applied on GCE surfaces were analyzed in detail under a three-dimensional (3D) microscope and were used as chemosensors of four pyrazine drugs in stoichiometric tests. The results were compared with the measurements made on an unmodified GCE. To obtain reliable results, the linearity of measurements was also verified in the concentration gradient and appropriate scanning speed was chosen to achieve the most accurate measurements.

Chemosensors published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, Name: Pyrazine-2-carbothioamide.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Kushner, S. published the artcileExperimental chemotherapy of tuberculosis. II. The synthesis of pyrazinamides and related compounds, Application In Synthesis of 4604-72-2, the publication is Journal of the American Chemical Society (1952), 3617-21, database is CAplus.

cf. C.A. 43, 5025b. To 5.0 g. 2-aminothiazole was added slowly a suspension of 3.5 g. freshly prepared pyrazinoyl chloride (I) in 15 cc. EtOAc, the mixture heated 10 min. on a steam bath, the supernatant hot EtOAc decanted, the residue heated again with 15 cc. EtOAc, the procedure repeated, the combined EtOAc-layers were evaporated to dryness, and the solid, yellow residue was washed with cold H₂O, filtered, dried, and recrystallized from hot EtOAc to give 3.0 g. (60%) N-(2-thiazolyl)pyrazinamide, m. 187-9°. By the same procedure were prepared the following N-mono- or N,N-disubstituted pyrazinamides (substituent given): Me, m. 105°; Me₂, m. 70-2°; Bu 20%, b₃ 167-70°; C₁₆H₃₃ 50%, m. 85-7° (from C₆H₆-EtOH); PhCH₂, m. 116-18°; Ph 55-60%, m. 127-30°; p-ClC₆H₄ 60%, m. 184-5°; o-ClC₆H₄ 60%, m. 135-6°; m-ClC₆H₄ 60%, m. 145-7°; 2-pyridyl, 65%, m. 138-40°; 3-pyridyl 62%, m. 185-6°; 1-piperidyl 80%, m. 68-9° (from Me₂CO); 3-quinoxalyl 76%, m. 205-6°; and 2-pyrazinyl 40%, m. 190-2°. Et N-pyrazinoyl-β-alanate (II) (1 g.) in 25 cc. MeOH saturated with NH₃ at 0° gave 55% β-(N’-pyrazinoylamino)propionamide, m. 206-8°. Me pyrazinoate (III) (5.0 g.), 7.5 g. HO(CH₂)₂NHCH₂CH₂NH₂, and 30 cc. absolute EtOH refluxed 60 hrs. gave 84% N-(2-hydroxyethyl)-N’-pyrazinoylethylene-diamine, m. 107-8°. Similarly were prepared from III and iso-BuNH₂, N-isobutylpyrazinamide, m. 63-4° (from C₆H₆-EtOH); and from III and p-MeOC₆H₄CH₂NH₂, 50% N-(p-methoxybenzyl)pyrazinamide m. 134-6°. By ammonolysis of the appropriate, substituted pyrazinoates were prepared the following substituted pyrazinamides (substituents given): 6-Me, 83%, m. 204-5° (from EtOH); 3-H₂N ,50%, m. 237-9°; 3-amino-6-bromo (IV) 80%, m. 215-17°; 3-HO, m. 265° (decomposition). 2,3-Pyrazinedicarboxamide (V) m. 240°, (decomposition); 2,6-isomer, 90%, m. 300° (decomposition); 6-Me derivative of IV, 80%, m. 215-17°. To 15 g. H₂N(CH₂)₂-CH:CHCO₂H and 5.2 g. NaOH in 100 cc. ice-cold H₂O were added simultaneously during 30 min. with stirring 9 g. NaOH in 50 cc. H₂O and 10 g. I in 50 cc. C₆H₆, the mixture was stirred 30 min. at room temperature, the C₆H₆ removed in vacuo, and the resulting aqueous solution acidified with 6N HCl to give 70% 5-pyrazinoylamino-2-pentenoic acid, m. 200-1°. By the same procedure but with NaHCO₃ were prepared 70% di-Et N-pyrazinoylaspartate, m. 64-5°, and 50% II, m. 87-9°. Cyanopyrazine (VI), b_6-7 86-7°, (21.9 g.) in 125 cc. dry Et₂O and 8.4 g. absolute MeOH saturated with HCl at 0° and the mixture let stand 15 hrs. at room temperature gave 25.6 g. Me pyrazinimidate-2HCl, m. above 150° (with darkening and decomposition); this was added to 600 cc. ice-cold 8% alc. NH₃, the mixture shaken 1 day at room temperature, filtered, the filtrate evaporated to dryness in vacuo, and the solid residue boiled briefly with 125 cc. Me₂CO, filtered, and crystallized from EtOH to give 6 g. pyrazinecarboxamidine-HCl, m. 215-18° (decomposition); picrate, m. 221-4°. VI (15 g.) in 200 cc. saturated, alc. NH₃ saturated with H₂S and the mixture let stand overnight at room temperature yielded 90% thiocarbamyl-pyrazine, m. 195-6°. To 13.8 g. III and 7 g. NH₂OH.HCl in 50 cc. ice-water was added 16 cc. 12.5 N NaOH, and the mixture let stand 15 min. in an ice bath and neutralized with HCl to give 72% pyrazinohydroxamic acid, m. 163-5° (from H₂O), gives a wine color with alc. FeCl₃. Pyrazinamide (VII) (21 g.), 84 cc. AcOH, and 210 cc. 30% H₂O₂ heated 34 hrs. at 56° gave 45% pyrazinoic acid 4-oxide, m. 292-3° (decomposition) (from AcOH), also obtained by similar oxidation of VI. VII (10 g.) and 17 g. MeI refluxed 12 hrs. in 100 cc. MeOH yielded 38% 3-carbamyl-1-methylpyrazinium iodide (VIII), m. 192-202° (from H₂O). VII (4 g.) refluxed 1.25 hrs. with 20 cc. Ac₂O gave 55% N-Ac derivative (IX), of VII, m. 92-7°. VII (15 g.), 18 cc. aqueous CH₂O, and 0.2 g. K₂CO₃ heated on a steam bath until a clear solution was formed yielded 80% N-(hydroxymethyl)pyrazinamide, m. 129-36.5°. 1-Phenylsulfonyl-2-pyrazinoylhydrazine (X) 86% was obtained from PhSO₂Cl and pyrazinoic acid hydrazide(XI),m. 169°. Dry X(10g.)and 18g. finely powd. Na₂CO₃ heated at 150-70° and 35 mm. pressure, and the vapors bubbled through 3% aqueous H₂NC(:S)NHNH₂ gave 9% pyrazinaldehyde thiosemicarbazone (XII), m. 237-9° (decomposition). XI (2.8 g.) and 3.3 g. p-AcNHC₆H₄CHO in 100 cc. absolute EtOH refluxed 5 min. yielded 92% pyrazinoic acid (p-acetamidobenzylidene)hydrazide, m. above 250°. To MeMgI (from 50 g. MeI and 9 g. Mg) in 300 cc. dry Et₂O was added dropwise over 20 min. 13 g. VI in 150 cc. Et₂O, and the mixture poured on ice and acidified to give 77% acetylpyrazine (XIII), m. 76-8° (from Et₂O); thiosemicarbazone (XIV), 67%, m. 226-7° (decomposition); oxime, 50%, m. 113-15° (sublimed at 100° and 0.05 mm.). Powd. S (1.5 g.) in 15 cc. concentrated NH₄OH saturated with H₂S, 3.0 g. XIII, and 12 cc. dioxane heated 24 hrs. in a sealed tube at 170° gave 0.2 g. pyrazinacetamide, m. 108-10° (from EtOH-petr. ether). XIII (12.2 g.), 5.2 g. S, and 15 cc. morpholine refluxed 6 hrs. yielded 80% 4-(2-pyrazinylthioacetyl)morpholine, m. 92-3°. HCl passed through 29.6 g. pyrazinyldiazomethyl ketone (XV) in 600 cc. dry Et₂O until the N evolution ceased gave 30% (chloroacetyl)pyrazine, m. 85-6°; thiosemicarbazone, 30%, m. 222-4°. To 30 cc. glacial AcOH was added at 50° in portions 6.4 g. XV, and, after all the N had been evolved, 0.5 g. KOAc, the mixture heated 1 hr. at 100°, and the AcOH distilled off in vacuo to yield 10% (acetoxyacetyl)pyrazine, m. 67-8°. VI (5.1 g.), 3.3 g. NaN₃, 10 cc. glacial AcOH and 15 cc. iso-PrOH autoclaved 5 days at 150° gave 30% 5-pyrazinyl-1H-tetrazole, m. 182-4°. Concentrated aqueous solutions of 2-aminopyrazine and KSCN mixed and acidified during 1 hr. with 1 molar equivalent HCl gave 80% 1-pyrazinyl-2-thiourea, m. 128°. PhONa (36 g.) and 36 g. chloropyrazine refluxed 13 hrs. yielded 72% Ph pyrazinyl ether, m. 50-2°. 3-Methyl-2-quinoxalincarboxaldehyde thiosemicarbazone (XVI), m. 251-2° (decomposition) was obtained in 30% yield by refluxing the components 2 hrs. in absolute EtOH. All above mentioned pyrazine derivatives were tested in a standardized mouse test for T. B. activity at the arbitrary level of 0.2% of diet (8 mg./day), with survival as a criterion. VII, m. 189-91°, was highly active, and IX and XII showed a slight activity. All others were inactive; IV, V, VIII, X, XI, XII, and XIV were also toxic. The following addnl. pyrazine derivatives (substituents and m.ps. given) were also tested and found inactive: CO₂H, 225-6°; C(OAc):NH.2HCl, 180°; CO₂-Me.HCl, 46°; 6,2-Me(HO₂C), 138-40°; 2,3-(HO₂C)₂, 179-82°; 2,3-CONHCO-, m. 245°; and 6,2,3-Me(HO₂C)₂, 43.4°. XVI, 2-chloro-3-quinoxalinecarboxamide (XVII), m. 207-9°, and its N-PhCH₂ derivative did not exhibit T.B. activity in the above test.

Journal of the American Chemical Society published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, Application In Synthesis of 4604-72-2.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Dhumal, Sambhaji T. published the artcileSynthesis and Antitubercular activity of New Thiazolidinones with Pyrazinyl and Thiazolyl scaffolds, Category: pyrazines, the publication is Journal of Heterocyclic Chemistry (2017), 54(1), 125-130, database is CAplus.

Emergence of multidrug resistant and extensively drug resistant tuberculosis has prompted to develop new mol. entities to treat the disease. A series of new 4-thiazolidinones with pyrazinyl and thiazolyl scaffolds has been synthesized, and their antitubercular activity is reported. The title 4-thiazolidinones, N-(pyrazinyl substituted thiazoloylamino)-2-aryl-4-thiazolidinones I [ R = H, 4-Me, 2-F, etc] have been first time prepared using pyrazinamide as a starting material via five successive steps. The purity and the structures of the intermediates (carboethoxythiazole, acid hydrazide, and azomethines) and title thiazolidinones I [ R = H, 4-Me, 2-F, etc] have been confirmed by TLC and spectral analyses, resp. An antitubercular screening of the new 4-thiazolidinones has been performed on bacterial strains, Mycobacterium tuberculosis H37Ra and Mycobacterium BCG using the solutions of different concentrations of the compounds I [ R = H, 4-Me, 2-F, etc] and the screening results are presented. Compound I [ R = H] has displayed notable antitubercular activity.

Journal of Heterocyclic Chemistry published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, Category: pyrazines.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Krinkova, Jana published the artcileIn vitro antifungal activity of 5-alkyl-6-chloropyrazine-2-carboxamides and the corresponding thioamides, Product Details of C5H5N3S, the publication is Folia Pharmaceutica Universitatis Carolinae (2001), 21-26, database is CAplus.

Homolytic alkylation of 6-chloropyrazine-2-carbonitrile by alkanoic acids and subsequent partial hydrolysis afforded 5-alkyl-6-chloropyrazine-2-carboxamides, which were converted by Lawesson’s reagent into corresponding thioamides. Products were tested for their in vitro antifungal activity. The structure-activity relationships were studied. Three of the tested compounds, 6-chloro-5-butylpyrazine-2-carbothioamide, 6-chloro-5-isobutylpyrazine-2-carbothioamide, and 6-chloro-5-(1,1-dimethylethyl)-pyrazine-2-carbothioamide, were active in vitro against all 8 strains tested (MIC values ranged from 62.5 to 500 μmol.dm^-3). Thioamides exerted higher antifungal activity than the corresponding amides. The values of hydrophobicity in the series of studied compounds were determined The activity dropped or disappeared at the compounds with lower lipophilicity (log P > 2.28). Some interesting correlation between antimycobacterial and antifungal activity was found.

Folia Pharmaceutica Universitatis Carolinae published new progress about 4604-72-2. 4604-72-2 belongs to pyrazines, auxiliary class Pyrazine,Amine,Amide, name is Pyrazine-2-carbothioamide, and the molecular formula is C5H5N3S, Product Details of C5H5N3S.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem

Meegalla, Sanath K. published the artcileSynthesis and GABA receptor potency of 3-thiomethyl-4-(hetero)aryl-5-amino-1-phenylpyrazoles, Computed Properties of 762263-64-9, the publication is Bioorganic & Medicinal Chemistry Letters (2004), 14(19), 4949-4953, database is CAplus and MEDLINE.

A convenient synthetic route to 4-arylpyrazoles, e.g., I, is described. The potential for insecticidal activity through GABA channel blockage by this series of compounds, as well as their selectivity for insect vs. mammalian receptors, were explored through in vitro and in vivo assays.

Bioorganic & Medicinal Chemistry Letters published new progress about 762263-64-9. 762263-64-9 belongs to pyrazines, auxiliary class Pyrazine,Boronic acid and ester,Boronic Acids, name is Pyrazin-2-ylboronic acid, and the molecular formula is C4H5BN2O2, Computed Properties of 762263-64-9.

Referemce:
https://en.wikipedia.org/wiki/Pyrazine,
Pyrazine | C4H4N2 – PubChem