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Journal articles on the topic 'Pyrazine ring'

Author: Grafiati

Published: 5 June 2025

Last updated: 1 August 2025

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1

Jigajinni, V. B., P. N. Preston, V. K. Shah, S. W. Simpson, I. Soutar, and N. J. Stewart. "Structure-property relationships in PMR-15-type polyimide resins: IIH. New polyimides incorporating triazoles, quinoxalines, pyridopyrazines and pyrazinopyridazines." High Performance Polymers 5, no. 3 (1993): 239–57. http://dx.doi.org/10.1088/0954-0083/5/3/008.

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Polyimide oligomers (prepolymers) and resins of the PMR-15 type have been prepared from 5-norbomene-2,3-dicarboxylic half acid ester (NE), 3,3',4,4'-benzophenone tetracarboxylic diester (BTDE) and a series of diamines incorporating 1,2,3-triazole, quinoxaline, pyrido[2,3-b]pyrazine, pyrido[3,4-b]pyrazine, benzo[g]quinoxaline, pyrazino-[2,3]-d]pyridazine and bis(pyrido[3,4-b]pyrazino)benzene ring systems. Two tetraamines in the bis(pyrazino[2,3-d]pyridazino)benzene ring system were also employed. Selected diamine monomers from the above ring systems provde PMR-15-analogue resins of higher therm

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2

Ma, Yun-Jiao, Jian-Hai Wu, Xiang Li, et al. "Effect of alkyl distribution in pyrazine on pyrazine flavor release in bovine serum albumin solution." RSC Advances 9, no. 63 (2019): 36951–59. http://dx.doi.org/10.1039/c9ra06720e.

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The methyl groups on the pyrazine ring affect the interaction of pyrazines with BSA. The non-covalent interaction between alkyl-pyrazines and BSA was confirmed. Alkyl-pyrazines could induce the polarity and conformation change of BSA.

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3

Tong, Wenhua, Shuqin Wang, Haoran Xu, Zongwei Qiao, Liming Zhao, and Ying Yang. "Interaction and Binding Kinetics of Different Substituted Pyrazines with HSA: Based on Multispectral, Physiological Activity, and Molecular Dynamics Simulations." Journal of Food Biochemistry 2024 (March 25, 2024): 1–20. http://dx.doi.org/10.1155/2024/4373558.

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Pyrazine is a kind of compound containing pyrazine ring structure, which has attracted the attention of researchers because of its special aroma and healthcare function. It is currently used in spices, pharmaceuticals, food additives, and other industries. Human serum albumin (HSA) is a transport and storage protein in the human circulatory system. Previous research reported that pyrazine can interact with albumin, but the interaction between pyrazine and HSA has not been reported. Consequently, this study is based on the multispectral method and molecular dynamics (MD) simulation, exploring t

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4

Alfonso, Montserrat, and Helen Stoeckli-Evans. "Dimethyl and diethyl esters of 5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylic acid: a comparison." Acta Crystallographica Section E Crystallographic Communications 72, no. 2 (2016): 233–37. http://dx.doi.org/10.1107/s2056989016001080.

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In dimethyl 5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylate, C18H14N4O4, (I), and diethyl 5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylate, C20H18N4O4, (II), the dimethyl and diethyl esters of 5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylic acid, the orientation of the two pyridine rings differ. In (I), pyridine ringBis inclined to pyrazine ringAby 44.8 (2)° and the pyridine and pyrazine N atoms aretransto one another, while pyridine ringCis inclined to the pyrazine ring by 50.3 (2)°, with the pyridine and pyrazine N atomscisto one another. In compound (II), the diethyl ester, which possesses tw

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5

Pacifico, Jessica, and Helen Stoeckli-Evans. "A new tetrakis-substituted pyrazine carboxylic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(sulfanediyl)}tetrapropionic acid: crystal structures of two triclinic polymorphs and of two potassium–organic frameworks." Acta Crystallographica Section E Crystallographic Communications 77, no. 5 (2021): 480–90. http://dx.doi.org/10.1107/s2056989021003479.

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Two polymorphs of the title tetrakis-substituted pyrazine carboxylic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene))tetrakis(sulfanediyl]}tetrapropionic acid, C20H28N2O8S4, (H4L1), have been obtained, H4L1_A and H4L1_B. Each structure crystallized with half a molecule in the asymmetric unit of a triclinic P\overline{1} unit cell. The whole molecules are generated by inversion symmetry, with the pyrazine rings being located about inversion centers. The crystals of H4L1_B were of poor quality, but the X-ray diffraction analysis does show the change in conformation of the –CH2—

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6

Tesouro Vallina, Ana, and Helen Stoeckli-Evans. "Crystal structures and Hirshfeld surface analyses of two new tetrakis-substituted pyrazines and a degredation product." Acta Crystallographica Section E Crystallographic Communications 76, no. 3 (2020): 404–9. http://dx.doi.org/10.1107/s2056989020002133.

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The two new tetrakis-substituted pyrazines, 1,1′,1′′,1′′′-(pyrazine-2,3,5,6-tetrayl) tetrakis(N,N-dimethylmethanamine), C16H32N6, (I) and N,N′,N′′,N′′′-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline), C36H40N6, (II), both crystallize with half a molecule in the asymmetric unit; the whole molecules are generated by inversion symmetry. There are weak intramolecular C—H...N hydrogen bonds present in both molecules and in (II) the pendant N-methylaniline rings are linked by a C—H...π interaction. The degredation product, N,N′-[(6-phenyl-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazine-

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7

ONG, KOK TONG, ZHI-QIANG LIU, and MENG GUAN TAY. "Review on the Synthesis of Pyrazine and Its Derivatives." Borneo Journal of Resource Science and Technology 7, no. 2 (2017): 60–75. http://dx.doi.org/10.33736/bjrst.591.2017.

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Pyrazine is a kind of natural product which can be found in plants, animals, insects, marine organisms andmicroorganisms. The main function of pyrazine in living organisms is used as flavor of the raw foods. Pyrazine and its derivatives were also produced in industries mainly for fragrance, flavor and pharmaceutical applications. This review describes the historical development of pyrazine including the discovery and synthesis, to the recent synthetic approach of pyrazinium. In general, six synthetic approaches namely condensation reaction, ring closure, metal catalysis, green reaction, Mailla

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8

Ge, Guo-Ping, та Chun-Yan Li. "(Acetylacetonato-κ2O,O′)bis{5-fluoro-2-[3-(4-fluorophenyl)pyrazin-2-yl]phenyl-κ2N1,C1}iridium(III)". Acta Crystallographica Section E Structure Reports Online 68, № 8 (2012): m1079. http://dx.doi.org/10.1107/s1600536812031546.

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In the title complex, [Ir(C16H9F2N2)2(C5H7O2)], the IrIIIatom, lying on a twofold rotation axis, is hexacoordinated in a distorted octahedral geometry by twoC,N-bidentate 5-fluoro-2-[3-(4-fluorophenyl)pyrazin-2-yl]phenyl ligands and oneO,O′-bidentate acetylacetonate ligand. The dihedral angles between the benzene rings and the pyrazine ring are 14.66 (8) and 49.76 (12)°.

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9

Mague, Joel T., Shaaban K. Mohamed, Mehmet Akkurt, Talaat I. El-Emary, and Mustafa R. Albayati. "Crystal structure of 5-(4,5-dihydro-1H-imidazol-2-yl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyrazin-6-amine." Acta Crystallographica Section E Structure Reports Online 70, no. 11 (2014): o1212—o1213. http://dx.doi.org/10.1107/s160053681402354x.

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In the title compound, C15H15N7, the phenyl ring is inclined by 19.86 (5)° to the mean plane of the pyrazolo[3,4-b]pyrazine core. In the crystal, N—H...N and C—H...N hydrogen bonds form [010] chains, which stackviaπ–π interactions [centroid–centroid distance between the pyrazole rings = 3.4322 (7) Å].

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10

Garduño-Alva, Azucena, M. Carmen Ortega-Alfaro, José G. López-Cortés та ін. "Synthesis of new γ-lactones from preactivated monosubstituted pyrazines and TMS–ketene acetals". Canadian Journal of Chemistry 90, № 5 (2012): 469–82. http://dx.doi.org/10.1139/v2012-016.

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The double addition of bis(trimethylsilyl) ketene acetals (1a–1b, R1 = CH3, –(CH2)5–) to 2-substituted pyrazines promoted by triflic anhydride leads to γ-lactones in a single step. A systematic study involving electron-withdrawing and electron-donating groups (R2 = CN, COOMe, PhCH=CH, Cl, Me, OMe) in the pyrazine ring reveals a strong dependence of electronic effects on the regiochemistry of nucleophilic addition.

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11

Wang, Yi, and Helen Stoeckli-Evans. "The inner-salt zwitterion, the dihydrochloride dihydrate and the dimethyl sulfoxide disolvate of 3,6-bis(pyridin-2-yl)pyrazine-2,5-dicarboxylic acid." Acta Crystallographica Section C Crystal Structure Communications 68, no. 11 (2012): o431—o435. http://dx.doi.org/10.1107/s0108270112039534.

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In the inner-salt zwitterion of 3,6-bis(pyridin-2-yl)pyrazine-2,5-dicarboxylic acid, (I), namely 5-carboxy-3-(pyridin-1-ium-2-yl)-6-(pyridin-2-yl)pyrazine-2-carboxylate, [C16H10N4O4, (Ia)], the pyrazine ring has a twist–boat conformation. The opposing pyridine and pyridinium rings are almost perpendicular to one another, with a dihedral angle of 80.24 (18)°, and are inclined to the pyrazine mean plane by 36.83 (17) and 43.74 (17)°, respectively. The carboxy and carboxylate groups are inclined to the mean plane of the pyrazine ring by 43.60 (17) and 45.46 (17)°, respectively. In the crystal str

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12

Zhang, Jinpeng, Yinan Wang, Qian Wang, and Lichun Xu. "6,7-Dichloro-3-(2,4-dichlorobenzyl)quinoxalin-2(1H)-one." Acta Crystallographica Section E Structure Reports Online 68, no. 8 (2012): o2481. http://dx.doi.org/10.1107/s160053681203098x.

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In the title compound, C15H8Cl4N2O, the quinoxaline ring system is almost planar, with a dihedral angle between the benzene and pyrazine rings of 3.1 (2)°. The 2,4-dichlorophenyl ring is approximately perpendicular to the pyrazine ring, with a dihedral angle of 86.47 (13)° between them. The crystal packing features intermolecular N—H...O hydrogen bonds and π–π stacking interactions, with centroid–centroid distances in the range 3.699 (3)–4.054 (3) Å.

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13

Wang, Ye-Nan, та Wen-Wen Dong. "Diaquabis[5-(pyrazin-2-yl-κN1)-3-(pyridin-3-yl)-1,2,4-triazolido-κN1]zinc". Acta Crystallographica Section E Structure Reports Online 70, № 4 (2014): m116. http://dx.doi.org/10.1107/s1600536814004176.

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In the title compound, [Zn(C11H7N6)2(H2O)2], the ZnIIcation, located on an inversion center, isN,N′-chelated by two 5-(pyrazin-2-yl)-3-(pyridin-3-yl)-1,2,4-triazolide anions and is further coordinated by two water molecules in a distorted N4O2octahedral geometry. In the anionic ligand, the pyrazine and pyridine rings are twisted with respect to the central triazole ring by 5.77 (10) and 11.54 (10)°, respectively. In the crystal, classical O—H...N and weak C—H...O hydrogen bonds and π–π stacking interactions between aromatic rings [the centroid–centroid distances between triazole and pyrazine r

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14

Schmitt, Laurette, and Helen Stoeckli-Evans. "Crystal structure of 2,5-bis(4-methylpyridin-2-yl)pyrazine chloroform disolvate." Acta Crystallographica Section E Structure Reports Online 70, no. 9 (2014): o893—o894. http://dx.doi.org/10.1107/s1600536814009544.

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The heterocyclic molecule in the title solvate, C16H14N4·2CHCl3, possesses inversion symmetry, with the inversion centre situated at the centre of the pyrazine ring. The outer pyridine rings are inclined to the central pyrazine ring by 4.89 (9)°. The compound crystallized as a chloroform disolvate with the solvent molecules linked to the title molecule by C—H...N hydrogen bonds. In the crystal, molecules are further linked by π–π interactions involving the pyrazine and pyridine rings of neighbouring molecules [inter-centroid distance = 3.5629 (12) Å; symmetry code:x,y + 1,z + 1].

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15

Assoumatine, Tokouré, and Helen Stoeckli-Evans. "Crystal structure of 2,3,5,6-tetrakis[(methylsulfanyl)methyl]pyrazine." Acta Crystallographica Section E Structure Reports Online 70, no. 9 (2014): o887—o888. http://dx.doi.org/10.1107/s1600536814011246.

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The title compound, C12H20N2S4, synthesized by the reaction of 2,3,5,6-tetrakis(bromomethyl)pyrazine with sodium methanethiolate, crystallizes with a half -molecule in the asymmetric unit. The whole molecule is generated by inversion symmetry; the inversion centre being located in the centre of the pyrazine ring. The molecule has an S-shaped conformation with two (methylsulfanyl)methyl substituent arms directed above the plane of the pyrazine ring and two below. The C(H3)—S—C(H2)—C(aromatic) torsion angles are 70.47 (18) and −67.65 (17)°, respectively. In the crystal, molecules are linkedviawe

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16

Begum, Shaheen, M. S. Rashida Anjum, G. Poojitha Harisree, N. Sivalakshmi, P. Priyanka, and K. Bharathi. "Antioxidant Activity of Piperazine Compounds: A Brief Review." Asian Journal of Chemistry 32, no. 9 (2020): 2105–18. http://dx.doi.org/10.14233/ajchem.2020.22832.

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Piperazine ring is found in several potent antioxidant molecules. Literature survey revealed that the piperazine ring has been coupled to different heterocyclic rings such as quinoline, pyridine, pyrazine, azole, 1,3,4-oxadiazole, 1,4-benzodioxane, pyrrolidinone, benzimidazole, pyrazine benzimidazole to obtain compounds with good antioxidant activity. It is found that the natural compounds like α-lipoic acid, methylxanthine, berberine, sarsasapogenin, chrysin, chromen-4-one, co-enzyme Q when attached to piperazine ring, antioxidant activity was improved. In the present article, piperazine cont

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17

Assoumatine, Tokouré, and Helen Stoeckli-Evans. "Crystal structure of a tetrakis-substituted pyrazine compound: 2,3,5,6-tetrakis(bromomethyl)pyrazine." Acta Crystallographica Section E Structure Reports Online 70, no. 8 (2014): 51–53. http://dx.doi.org/10.1107/s1600536814011337.

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The title compound, C8H8Br4N2, crystallizes in the enantiomorphic-defining space groupP41212 and has a refined Flackxparameter of 0.04 (4). In the asymmetric unit, there are two half-molecules; the whole molecules (AandB) are generated by twofold rotation symmetry. In moleculeA, the twofold axis is normal to the pyrazine ring passing through the centre of the ring, while in moleculeB, the twofold rotation axis lies in the plane of the pyrazine ring bisecting the C—C aromatic bonds. The two molecules are pseudo-mirror images of one another, and the best fit of the two molecules was obtained for

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18

Wang, Shijun, Xiaorong Yuan, Hao Qian, Na Li, and Junru Wang. "Design, Synthesis, and Biological Evaluation of Two Series of Novel A-Ring Fused Steroidal Pyrazines as Potential Anticancer Agents." International Journal of Molecular Sciences 21, no. 5 (2020): 1665. http://dx.doi.org/10.3390/ijms21051665.

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Background: Increasingly, different heterocyclic systems have been introduced into the steroid nucleus to significantly enhance the antitumor activities of steroid molecules. However, in this study, few literature precedents describing the pyrazine heterocyclic-condensed modification to an A-ring of steroid monomers were found, although the pyrazine group is thought to be essential for the potent anticancer activity of clinically relevant drugs and natural steroid dimers. Methods and Results: Two series of novel A-ring fused steroidal pyrazines were designed and efficiently synthesized from co

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19

Wentrup, Curt, Ales Reisinger, and David Kvaskoff. "4-Pyridylnitrene and 2-pyrazinylcarbene." Beilstein Journal of Organic Chemistry 9 (April 17, 2013): 754–60. http://dx.doi.org/10.3762/bjoc.9.85.

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Both flash vacuum thermolysis (FVT) and matrix photolysis generate 2-diazomethylpyrazine (22) from 1,2,3-triazolo[1,5-a]pyrazine (24). FVT of 4-azidopyridine (18) as well as of 24 or 2-(5-tetrazolyl)pyrazine (23) affords the products expected from the nitrene, i.e., 4,4’-azopyridine and 2- and 3-cyanopyrroles. Matrix photolyses of both 18 and 24 result in ring expansion of 4-pyridylnitrene/2-pyrazinylcarbene to 1,5-diazacyclohepta-1,2,4,6-tetraene (20). Further photolysis causes ring opening to the ketenimine 27.

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20

Tomura, Masaaki, and Yoshiro Yamashita. "Tetrathiafulvalene with a fused pyrazine ring." Acta Crystallographica Section E Structure Reports Online 57, no. 4 (2001): o307—o308. http://dx.doi.org/10.1107/s1600536801003701.

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21

Armaghan, Mahsa, Tobias Stürzer, and Christoph Janiak. "Coordination Polymers with a Pyrazine-2,5-diyldimethanol Linker: Supramolecular Networks through Hydrogen and Halogen Bonds." Crystals 13, no. 8 (2023): 1193. http://dx.doi.org/10.3390/cryst13081193.

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In this paper, the synthesis and crystal structure of pyrazine-2,5-diyldimethanol (pyzdmH2, C6H8N2O2), a new symmetric water-soluble N,O-chelating tetra-dentate organic ligand, is reported and an environmentally friendly method is used to synthesize coordination compounds in water under ambient conditions, from the reaction of pyzdmH2 with the halide salts of Cu(II), Zn(II), Hg(II) and Cd(II): {[Cu(pyzdmH2)0.5(µ-Br)(Br)(H2O)]·H2O}n 1, {[Zn2(pyzdmH2)(µ-Cl)(Cl)3(H2O)]·H2O}n 2, [Hg2(pyzdmH2)0.5(µ-Cl)2(Cl)2]n 3, {[Cd2(pyzdmH2)(µ-Cl)4]·H2O}n 4, and {[Cd2(pyzdmH2)(µ-Br)4]·H2O}n 5. Single-crystal X-r

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22

Zheng, He-Qi, Lin Zhang, Mengting Lu, et al. "Precise Design and Deliberate Tuning of Turn-On Fluorescence in Tetraphenylpyrazine-Based Metal−Organic Frameworks." Research 2022 (October 17, 2022): 1–11. http://dx.doi.org/10.34133/2022/9869510.

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The manipulation on turn-on fluorescence in solid state materials attracts increasing interests owing to their widespread applications. Herein we report how the nonradiative pathways of tetraphenylpyrazine (TPP) units in metal−organic frameworks (MOFs) systems could be hindered through a topological design approach. Two MOFs single crystals of different topology were constructed via the solvothermal reaction of a TPP-based 4,4′,4″,4‴-(pyrazine-2,3,5,6-tetrayl) tetrabenzoic acid (H4TCPP) ligand and metal cations, and their mechanisms of formation have been explored. Compared with the innate low

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23

Assoumatine, Tokouré, and Helen Stoeckli-Evans. "The crystal structures, Hirshfeld surface analyses and energy frameworks of two hexathiapyrazinophane regioisomers; 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane and 2,5,8,11,14,17-hexathia-[9.9](2,5,3,6)-pyrazinophane." Acta Crystallographica Section E Crystallographic Communications 76, no. 7 (2020): 977–83. http://dx.doi.org/10.1107/s2056989020007057.

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The title thiapyrazinophanes, 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane, C16H24N2S6, (I), and 2,5,8,11,14,17-hexathia-[9.9](2,5,3,6)-pyrazinophane, C16H24N2S6, (II), are regioisomers; m-bis L1 and p-bis L1, respectively. Both compounds have a central tetra-2,3,5,6-methylenepyrazine unit with two –S—CH2—CH2—S—CH2—CH2—S– chains, linking the methylene C atoms at positions 2 and 6 and 3 and 5 on the pyrazine ring of I, but linking the methylene C atoms at positions 2 and 5 and 3 and 6 on the pyrazine ring of II. Both compounds crystallize with half a molecule in the asymmetric unit. The

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24

MISHRA, BRIJESH KUMAR, and N. SATHYAMURTHY. "STACKING INTERACTION IN PYRAZINE DIMER." Journal of Theoretical and Computational Chemistry 05, no. 03 (2006): 609–19. http://dx.doi.org/10.1142/s0219633606002532.

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The structure and stability of pyrazine dimer in different orientations have been investigated using second- and fourth-order Møller–Plesset perturbation theory (MP2, MP4) and coupled-cluster singles and doubles with non-iterative perturbative triples method [CCSD(T)] with various basis sets (6-31G*, 6-311G**, 6-311++G**, cc-pVDZ, aug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ). With the largest basis set (aug-cc-pVTZ) at the MP2 level of theory, the calculated binding energies (basis set superposition error corrected) for the sandwich, N–N axial-displaced, lateral-displaced, cross-displaced, T-shaped

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25

Heirtzler, Fenton R. "Synthesis and Supramolecular Chemistry of 2,3-Bis(2,2'-oligopyridyl)pyrazines." CHIMIA 53, no. 5 (1999): 204. https://doi.org/10.2533/chimia.1999.204.

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Methods are being developed for the synthesis of pyrazine derivatives which are 2,3-disubstituted with 2,2'-oligopyridyl chains. We are currently investigating the supramolecular topology and complexation behavior of these novel compounds. These two aspects of their behavior appear to be largely determined by steric and electronic effects associated with the structure of the pyrazine ring.

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26

Chen, Guo-Qing, Hong-Yan Guo, Zhe-Shan Quan, Qing-Kun Shen, Xiaoting Li, and Tian Luan. "Natural Products–Pyrazine Hybrids: A Review of Developments in Medicinal Chemistry." Molecules 28, no. 21 (2023): 7440. http://dx.doi.org/10.3390/molecules28217440.

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Pyrazine is a six-membered heterocyclic ring containing nitrogen, and many of its derivatives are biologically active compounds. References have been downloaded through Web of Science, PubMed, Science Direct, and SciFinder Scholar. The structure, biological activity, and mechanism of natural product derivatives containing pyrazine fragments reported from 2000 to September 2023 were reviewed. Publications reporting only the chemistry of pyrazine derivatives are beyond the scope of this review and have not been included. The results of research work show that pyrazine-modified natural product de

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27

Fernandes, José A., Bing Liu, João P. C. Tomé, Luís Cunha-Silva, and Filipe A. Almeida Paz. "Crystal structure of 5-amino-4H-1,2,4-triazol-1-ium pyrazine-2-carboxylate: an unexpected salt arising from the decarboxylation of both precursors." Acta Crystallographica Section E Crystallographic Communications 71, no. 7 (2015): 840–43. http://dx.doi.org/10.1107/s205698901501172x.

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Both the 3-amino-2H,4H-1,2,4-triazolium cation and the pyrazine-2-carboxylate anion in the title salt, C2H5N4+·C5H3N2O2−, were formed by an unexpected decarboxylation reaction, from 5-amino-1H-1,2,4-triazole-3-carboxylic acid and pyrazine-2,3-dicarboxylic acid, respectively. The dihedral angle between the pyrazine ring (r.m.s. deviation = 0.008 Å) and the carboxylate group in the anion is 3.7 (3)°. The extended structure of the salt contains a supramolecular zigzag tape in which cations and anions are engaged in strong and highly directional N—H...N,O hydrogen bonds, formingR22(8) andR22(9) gr

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28

Chandralekha, Kuppan, Adukamparai Rajukrishnan Sureshbabu, Deivasigamani Gavaskar, and Srinivasakannan Lakshmi. "Crystal structure of methyl 3′-benzamido-4′-(4-methoxyphenyl)-1′-methylspiro[indeno[1,2-b]quinoxaline-11,2′-pyrrolidine]-3′-carboxylate." Acta Crystallographica Section E Crystallographic Communications 72, no. 9 (2016): 1257–59. http://dx.doi.org/10.1107/s2056989016012469.

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In the title compound, C35H30N4O3, the spiro C atom connects the five-membered pyrrolidine ring and the indenoquinoxaline ring system. The pyrrolidine ring adopts a twist conformation. An intramolecular N—H...N interaction between the amino group and the pyrazine ring is observed. In the crystal, molecules are linked by a pairs of C—H...O hydrogen bonds, forming inversion dimers.

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29

Cati, Dilovan S., and Helen Stoeckli-Evans. "Crystal structures ofN-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (monoclinic polymorph) andN-(pyridin-4-ylmethyl)pyrazine-2-carboxamide." Acta Crystallographica Section E Structure Reports Online 70, no. 7 (2014): 18–22. http://dx.doi.org/10.1107/s1600536814009519.

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The title compounds, C11H10N4O (HL1) and C11H10N4O (HL2), are pyridine 2-ylmethyl and 4-ylmethyl derivatives, respectively, of pyrazine-2-carboxamide. HL1 was measured at 153 K and crystallized in the monoclinic space groupP21/cwithZ= 4. There has been a report of the same structure measured at room temperature but assumed to crystallize in the triclinic space groupP-1 withZ= 4 [Sasanet al.(2008).Monatsh. Chem.139, 773–780]. In HL1, the pyridine ring is inclined to the pyrazine ring by 61.34 (6)°, while in HL2 this dihedral angle is 84.33 (12)°. In both molecules, there is a short N—H...N inte

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30

Huang, Qi, Zhicheng Guo, Longyu Liao, Shilong Hao, Fude Nie, and Hongzhen Li. "Customization of the molecular structure to modulate the crystal packing style of energetic materials." Molecular Systems Design & Engineering 4, no. 5 (2019): 1032–38. http://dx.doi.org/10.1039/c9me00051h.

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31

Çelik, Fatih, Nefise Dilek, Nagihan Çaylak Delibaş, Hacali Necefoğlu та Tuncer Hökelek. "catena-Poly[[aquabis(4-formylbenzoato-κ2O1,O1′)cadmium]-μ-pyrazine-κ2N:N′]". Acta Crystallographica Section E Structure Reports Online 70, № 2 (2014): m37—m38. http://dx.doi.org/10.1107/s1600536813035010.

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The polymeric title compound, [Cd(C8H5O3)2(C4H4N2)(H2O)]n, contains two 4-formylbenzoate (FB) anions, one pyrazine molecule and one coordinating water molecule; the FB anions act as bidentate ligands. The O atom, the aldehyde H atom and the benzene ring of one of the FB anions are disordered over two positions. The O atoms were freely refined [refined occupancy ratio 0.79 (2):0.21 (2)], while the aldehyde H atoms and the benzene ring atoms were refined with fixed occupancy ratios of 0.8:0.2 and 0.5:0.5, respectively. In the ordered FB anion, the carboxylate group is twisted away from the attac

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32

Choudhury, Manisha, Vijayan Viswanathan, Ajay Kumar Timiri, Barij Nayan Sinha, Venkatesan Jayaprakash, and Devadasan Velmurugan. "Crystal structures and Hirshfeld surface analyses of 2-[(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(pyridin-2-yl)acetamide and 2-[(4,6-diaminopyrimidin-2-yl)sulfanyl]-N-(pyrazin-2-yl)acetamide." Acta Crystallographica Section E Crystallographic Communications 74, no. 5 (2018): 718–23. http://dx.doi.org/10.1107/s2056989018005704.

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In the title compounds, C11H12N6OS (I) and C10H11N7OS (II), the diaminopyrimidine ring makes dihedral angles of 71.10 (9)° with the pyridine ring in (I) and 62.93 (15)° with the pyrazine ring in (II). The ethanamine group, –CH2–C(=O)–NH– lies in the plane of the pyridine and pyrazine rings in compounds (I) and (II), respectively. In both compounds, there is an intramolecular N—H...N hydrogen bond forming anS(7) ring motif and a short C—H...O interaction forming anS(6) loop. In the crystals of both compounds, molecules are linked by pairs of N—H...N hydrogen bonds, forming inversion dimers with

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33

Wu, Yang, Wen-Zhen Wang, Rayyat Huseyn Ismayilov, Gene-Hsiang Lee, and Shie-Ming Peng. "A coordination polymer consisting of two different one-dimensional copper(II) chains." Acta Crystallographica Section C Structural Chemistry 70, no. 3 (2014): 285–88. http://dx.doi.org/10.1107/s2053229614002472.

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The title compound,catena-poly[[[diaqua(methanol-κO)copper(II)]-μ-N-(4-methylpyrimidin-2-yl-κN1)pyrazin-2-amine-κ2N1:N4] [[aqua(aqua/methanol-κO)(perchlorato-κO)copper(II)]-μ-N-(4-methylpyrimidin-2-yl-κN1)pyrazin-2-amine-κ2N1:N4] tris(perchlorate) methanol monosolvate 1.419-hydrate], {[Cu(C9H9N5)(CH3OH)(H2O)2][Cu(C9H9N5)(ClO4)(CH3OH)0.581(H2O)1.419](ClO4)3·CH3OH·1.419H2O}n, is a one-dimensional straight-chain polymer ofN-(4-methylpyrimidin-2-yl)pyrazin-2-amine (L) with Cu(ClO4)2. The complex consists of two crystallographically independent one-dimensional chains in which the CuIIatoms exhibit

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34

Cati, Dilovan S., and Helen Stoeckli-Evans. "Crystal structures ofN2,N3,N5,N6-tetrakis(pyridin-2-ylmethyl)pyrazine-2,3,5,6-tetracarboxamide andN2,N3,N5,N6-tetrakis(pyridin-4-ylmethyl)pyrazine-2,3,5,6-tetracarboxamide." Acta Crystallographica Section E Crystallographic Communications 73, no. 2 (2017): 300–305. http://dx.doi.org/10.1107/s205698901700127x.

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The title compounds, C32H28N10O4· unknown solvent, (I), and C32H28N10O4, (II), are pyrazine-2,3,5,6-tetracarboxamide derivatives. In (I), the substituents are (pyridin-2-ylmethyl)carboxamide, while in (II), the substituents are (pyridin-4-ylmethyl)carboxamide. Both compounds crystallize in the monoclinic space groupP21/n, withZ′ = 1 for (I), andZ′ = 0.5 for (II). The whole molecule of (II) is generated by inversion symmetry, the pyrazine ring being situated about a center of inversion. In (I), the four pyridine rings are inclined to the pyrazine ring by 83.9 (2), 82.16 (18), 82.73 (19) and 17.

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35

Peng, Hai Tao, Yue Zhi Cui, Tao Zhang, Yang Zhang, and Hai Xing Guan. "Optical Properties of Chromophores with Different Six-Membered N-Heterocyclic Aromatic Ring." Advanced Materials Research 236-238 (May 2011): 1598–602. http://dx.doi.org/10.4028/www.scientific.net/amr.236-238.1598.

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A series of intramolecular charge transfer (ICT) molecules containing six-membered N-heterocyclic electron acceptors, as well as their phenyl analogue, have been synthesized. The pyrazine derivatives exhibit the largest quantum yield, stokes shift and the longest emission maxima wavelength due to the appropriate electronegativity of pyrazine, while the triazine derivative has much lower quantum yield due to its too strong ICT. The methyl groups at N-heterocyclic rings also have influence on the optical properties by disturbing the molecular dipole moment.

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36

Samie, Ali, and Alireza Salimi. "Orientation-dependent conformational polymorphs in two similar pyridine/pyrazine phenolic esters." CrystEngComm 21, no. 24 (2019): 3721–30. http://dx.doi.org/10.1039/c8ce02107d.

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37

Xiao, Zhao-Xin, Hao Miao, Dong Shao, Hai-Yan Wei, Yi-Quan Zhang, and Xin-Yi Wang. "A family of lanthanide compounds with reduced nitronyl nitroxide diradical: syntheses, structures and magnetic properties." Dalton Transactions 47, no. 24 (2018): 7925–33. http://dx.doi.org/10.1039/c8dt01112e.

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38

Deady, LW, and NH Quazi. "Synthesis of Pyrazino[2,3-c]isoquinolinecarboxylic Acids and Related Compounds." Australian Journal of Chemistry 45, no. 12 (1992): 2083. http://dx.doi.org/10.1071/ch9922083.

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1-Methylisoquinoline-3,4-diamine has been synthesized and condensed with α-dicarbonyl compounds to give the fused pyrazine ring. Oxidation of methyl groups gives the 3- and 6-carboxylic acids. Nitration occurs in the benzenoid ring to give the single 10-nitro product, and formation of an unusual 6-trinitromethyl compound is also reported.

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39

GAUTAM, CHATTOPADHYAY. "Studies on the Effect of Alkali on the Compounds related to Aminoimidazoliumcarboxamides." Journal of Indian Chemical Society Vol. 67, June 1990 (1990): 509–11. https://doi.org/10.5281/zenodo.6203168.

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Department of Chemistry, Presidency College, Calcutta-700 079 <em>Manuscript received 25 September 1989,  accepted 22 January 1990</em> Studies on the Effect of Alkali on the Compounds related to Aminoimidazoliumcarboxamides

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40

Daev, Eugene V., Boris P. Surinov, and Anna V. Dukelskaya. "Response of immunocompetent cells of bone marrow and spleen of mouse males of several strains to stress and to pyrazine containing chemosignals." Ecological genetics 10, no. 2 (2012): 14–20. http://dx.doi.org/10.17816/ecogen10214-20.

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The quantity of antibody producing cells and mitotic disturbances in dividing bone marrow cells of mice were studied after exposure of animals to a physical stressor or various pyrazinecontaining chemosignals. Several different strains of mice were used. We demonstrate that immune suppression and destabilization of the chromosome apparatus in dividing cells depend on: а) mouse genotype and b) side chains position in the pyrazine ring. Importance of this effects in the light of wide usage of pyrazine containing substances in perfume industry, food production and pharmacology is discussed.

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41

Khalymbadzha, Igor, Ramil Fatykhov, Oleg Chupakhin та ін. "Transition-Metal-Free С–С Coupling of 5,7-Dihydroxybenzopyrones with Quinoxalones and Pteridinones". Synthesis 50, № 12 (2018): 2423–31. http://dx.doi.org/10.1055/s-0037-1609482.

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A new synthetic protocol for nucleophilic substitution of hydrogen in quinoxalones and pteridinones by the action of 5,7-dihydroxycoumarins and related m-dihydroxybenzene compounds has been developed. The C–C coupling reaction proved to proceed smoothly under rather mild conditions, thus giving the corresponding C–H functionalized products in good yields. The advantages of this environmentally benign protocol are high regio- and chemoselectivity, and an easy workup procedure. Direct incorporation of the coumarin moiety into the pyrazine ring in pteridines or quinoxalines provides a short pat

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42

Wang, Fengqing, Mengsha Wei, Xueyan Duan, et al. "Identification, synthesis and biological evaluation of pyrazine ring compounds from Talaromyces minioluteus (Penicillium minioluteum)." Organic Chemistry Frontiers 7, no. 22 (2020): 3616–24. http://dx.doi.org/10.1039/d0qo01030h.

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43

Ziembicka, Dagmara, Katarzyna Gobis, Małgorzata Szczesio, et al. "Synthesis and Biological Activity of Piperidinothiosemicarbazones Derived from Aminoazinecarbonitriles." Pharmaceuticals 16, no. 9 (2023): 1267. http://dx.doi.org/10.3390/ph16091267.

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To investigate how structural modifications affect tuberculostatic potency, we synthesized seven new piperidinothiosemicrabazone derivatives 8–14, in which three of them had a pyrazine ring replacing the pyridine ring. Derivatives 8–9 and 13–14 exhibited significant activity against the standard strain (minimum inhibitory concentration (MIC) 2–4 μg/mL) and even greater activity against the resistant M. tuberculosis strain (MIC 0.5–4 μg/mL). Additionally, the effects of compounds 8–9 were entirely selective (MIC toward other microorganisms ≥ 1000 μg/mL) and non-toxic (IC50 to HaCaT cells 5.8 to

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44

Cati, Dilovan S., and Helen Stoeckli-Evans. "Syntheses and crystal structures of a new pyrazine dicarboxamide ligand, N 2,N 3-bis(quinolin-8-yl)pyrazine-2,3-dicarboxamide, and of a copper perchlorate binuclear complex." Acta Crystallographica Section E Crystallographic Communications 76, no. 3 (2020): 332–38. http://dx.doi.org/10.1107/s2056989020001838.

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The title pyrazine dicarboxamide ligand, N 2,N 3-bis(quinolin-8-yl)pyrazine-2,3-dicarboxamide (H2L1), C24H16N6O2, has a twisted conformation with the outer quinoline groups being inclined to the central pyrazine ring by 9.00 (6) and 78.67 (5)°, and by 79.94 (4)° to each other. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming layers parallel to the (10\overline{1}) plane, which are in turn linked by offset π–π interactions [intercentroid distances 3.4779 (9) and 3.6526 (8) Å], forming a supramolecular three-dimensional structure. Reaction of the ligand H2L1 with Cu(ClO4)2

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45

Ahmad, Mushtaq, Shahid Hameed, M. Nawaz Tahir, Muhammad Anwar, and Muhammad Israr. "N′-[(E)-3-Bromobenzylidene]pyrazine-2-carbohydrazide." Acta Crystallographica Section E Structure Reports Online 69, no. 11 (2013): o1635. http://dx.doi.org/10.1107/s1600536813027426.

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In the title compound, C12H9BrN4O, the dihedral angle between the aromatic rings is 12.16 (12)°. An intramolecular N—H...N hydrogen bond closes anS(5) ring. In the crystal, C—H...O hydrogen bonds link the molecules intoC(6) chains propagating in [010]. Very weak aromatic π–π stacking [centroid–centroid separations = 3.9189 (15) and 3.9357 (15) Å] is also observed.

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46

Mailman, Aaron, Rakesh Puttreddy, Manu Lahtinen, Noora Svahn, and Kari Rissanen. "Hydrogen and Halogen Bond Mediated Coordination Polymers of Chloro-Substituted Pyrazin-2-Amine Copper(I) Bromide Complexes." Chemistry 2, no. 3 (2020): 700–713. http://dx.doi.org/10.3390/chemistry2030045.

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A new class of six mono- (1; 3-Cl-, 2; 5-Cl-, 3; 6-Cl-) and di-(4; 3,6-Cl, 5; 5,6-Cl-, 6; 3,5-Cl-) chloro-substituted pyrazin-2-amine ligands (1–6) form complexes with copper (I) bromide, to give 1D and 2D coordination polymers through a combination of halogen and hydrogen bonding that were characterized by X-ray diffraction analysis. These Cu(I) complexes were prepared indirectly from the ligands and CuBr2 via an in situ redox process in moderate to high yields. Four of the pyrazine ligands, 1, 4–6 were found to favor a monodentate mode of coordination to one CuI ion. The absence of a C6-chlo

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47

Karmakar, Ananta, Sridharan Ramalingam, Mushkin Basha та ін. "Facile Access to 1,4-Disubstituted Pyrrolo[1,2-a]pyrazines from α-Aminoacetonitriles". Synthesis 52, № 03 (2019): 441–49. http://dx.doi.org/10.1055/s-0039-1690699.

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An efficient and practical synthetic protocol for the synthesis of 1,4-disubstituted pyrrolo[1,2-a]pyrazine derivatives is described that originates from α-substituted pyrroloacetonitriles which, in turn, are readily available from aryl and alkyl aldehydes. The α-pyrroloacetonitriles were subjected to a Friedel–Crafts acylation with methyl chlorooxoacetate followed by reduction of the nitrile group under Pd-catalyzed hydrogenation conditions and finally aromatization with DDQ leading to the desired pyrrolo[1,2-a]pyrazine derivatives. This method was generalized and successfully applied to vari

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48

Aubert, Emmanuel, Victor Mamane, and Yves Fort. "S-Methyl 5-methylpyrazine-2-carbothioate." Acta Crystallographica Section E Structure Reports Online 63, no. 11 (2007): o4306—o4307. http://dx.doi.org/10.1107/s1600536807048970.

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The title compound, C7H8N2OS, can be a key synthetic intermediate for the preparation of various pyrazine compounds of biological interest. It was prepared by the hydrolysis of 2-tris(methylsulfanyl)methyl-5-methylpyrazine using the HgCl2/CaCO3 system. The molecule is quasi-planar; the H atoms of the methyl group linked to the pyrazine ring break the molecular mirror pseudosymmetry. One of these H atoms is involved in an intermolecular hydrogen bond with the carbonyl group of a neighbouring molecule. Two molecules related by an inversion centre interact through C—H...N hydrogen bonds, forming

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49

Albanez, Joselyn, Iván Brito, Alejandro Cárdenas та Matías López-Rodríguez. "Disorder in the anionic part ofcatena-poly[[(pyrazine-2-carboxylato)copper(II)]-μ-pyrazine-2-carboxylato]". Acta Crystallographica Section E Structure Reports Online 68, № 4 (2012): m498—m499. http://dx.doi.org/10.1107/s1600536812012378.

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The title compound, [Cu(C5H3N2O2)0.88(C6H4NO2)1.12]n, is characterized by disorder of the anion, resulting from a statistical occupation in a 0.44 (3):0.56 (3) ratio of pyrazine-2-carboxylate and pyridine-2-carboxylate. The compound was isolated during attempts to synthesize a mixed-ligand coordination polymer by solvothermal reaction between copper(II) nitrate and equimolar mixtures of pyrazine-2-carboxylic acid and pyridine-2-carboxylic acid in a mixture of water and EtOH. The difference in the two components of the compound is due to substitutional disorder of a CH group for one of the N at

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50

Shuai, Ying, Xiang-Yang Wang, Jing-Wei Dai, and Jian-Zhong Wu. "2-[2,6-Bis(pyrazin-2-yl)pyridin-4-yl]benzoic acid." Acta Crystallographica Section E Structure Reports Online 70, no. 5 (2014): o577—o578. http://dx.doi.org/10.1107/s1600536814008496.

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In the title compound, C20H13N5O2, the two pyrazine rings are nearly coplanar with the central pyridine ring, forming dihedral angles of 2.21 (9) and 4.57 (9)°. In contrast, the strong steric hindrance caused by theortho-carboxyl group on the phenyl ring makes this ring rotate out of the attached pyridine ring plane by 52.60 (9)°. The carboxyl group is twisted from the phenyl ring by 22.6 (1)°. In the crystal, aromatic π–π stacking interactions [centroid–centroid distances = 3.9186 (4) and 3.9794 (5) Å] occur between the antiparallel molecules, generating infinite chains along [100]. O—H...O h

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