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Pyrazines

Pyrazines are a class of heterocyclic aromatic compounds containing two nitrogen atoms in a six-membered ring.
These compounds are widely found in nature and have numerous applications, including use as flavoring agents, fragrance compounds, and pharmaceutical intermediates.
Pyrazines exhibit a variety of biological activities and have been studied for potential therapeutic applications in areas such as cancer, inflammation, and neurological disorders.
Understanding the properties and synthesis of pyrazines is crucial for researchers working in fields like organic chemistry, food science, and medicinal chemistry.
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Most cited protocols related to «Pyrazines»

To simplify this study, all characterized AFEX pretreatment-derived biomass decomposition products were divided into five groups (Table 4): 1) nitrogenous compounds, 2) furans, 3) aliphatic acids, 4) aromatic compounds, and 5) carbohydrates.

Plant cell wall-derived decomposition products and water-soluble extractives present in AFEX-CS hydrolysate (ACH)

CategoryCompoundConcentration (mg/L)
Nitrogenous compoundsFeruloyl amide1065
p-Coumaroyl amide886
Acetamide5674
2-Methylpyrazine10
2,5-Dimethylpyrazine1
2,6-Dimethylpyrazine4
2,4-Dimethyl-1 H-imidazole24
4-Methyl-1 H-imidazole95
Furan5-Hydroxymethyl furfural145
Aliphatic acidsMalonic acid33
Lactic acid181
cis-Aconitic acid111
Succinic acid60
Fumaric acid30
trans-Aconitic acid329
Levulinic acid2.5
Itaconic acid8.2
Acetic acid1958
Formic acid517
Aromatic compoundsVanillic acid15
Syringic acid15
Benzoic acid59
p-Coumaric acid345
Ferulic acid137
Cinnamic acid14
Caffeic acid2
Vanillin20
Syringaldehyde29.5
4-Hydroxybenzaldehyde24
4-Hydroxyacetophenone3.4
CarbohydratesGlucose60 g/L
Xylose26 g/L
Arabinose5 g/L
Gluco-oligomers12 g/L
Xylo-oligomers18 g/L

The concentration of nitrogenous compounds and furan were calculated from the content of the analyte in dry pretreated biomass [15 (link)] based on 18% solids loading (w/v) assuming 100% solubilization into the liquid phase.

The effect of these five groups of compounds on xylose fermentation was tested individually and in combination (five groups in combination) in order to investigate their synergistic inhibitory effect. The fermentations were conducted in SM supplemented with 60 g/L glucose and 26 g/L xylose. The decomposition products in each group and their concentrations are given in Table 2, and matched their absolute abundance as found in 6% glucan loading-based ACHs. To make stock solutions of decomposition products, all compounds were dissolved in water according to the categories of aliphatic acids, aromatic acids, aromatic aldehyde/ketones, furans, imidazoles, and pyrazines at 50-fold higher concentrations and the stock solutions were sterile filtered prior to their addition into the SM. Ferulic acid, p-coumaric acid, amides, and carbohydrates were directly added to the fermentation media at the desired concentrations (Table 2) due to their lower solubility in water. Fermentations of SM without any decomposition products (blank) and ACHs were used as negative and positive controls, respectively. The ACH was adjusted to pH 5.5 before inoculum addition.
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Publication 2015
Ache Acids Aconitum Aldehydes Aliphatic Acids Amides Carbohydrates Cell Wall Compounds, Nitrogen Fermentation ferulic acid furan Furans Glucans Glucose Imidazoles Ketones Methyl-gag Psychological Inhibition Pyrazines Sterility, Reproductive trans-3-(4'-hydroxyphenyl)-2-propenoic acid Xylose

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Publication 2013
Behavior Test Cocaine Genetic Selection MDL 100907 Methanol Normal Saline Pharmaceutical Preparations piperidine Pyrazines Receptor, Serotonin, 5-HT2C Saline Solution Serotonin 5-HT2A Receptor Antagonists Serotonin 5-HT2C Receptor Agonists Substance Abuse Detection
About 2 g of powdered rye-buckwheat biscuits were transferred into 22-mL headspace vials. The vials were sealed air-tight with a silicone/polytetrafluoroethylene (PTFE) septum. An aliquot of 2.5 mL of sodium chloride solution (25%) was added to each vial before capping and heating. A GC-MS method developed previously by Koutsidis et al. [38 (link)], was employed to quantitatively determine volatile compounds in the biscuits. The vials were then placed onto a COMBIPAL autosampler (CTC Analytics, Zwingen, Switzerland) coupled to an Agilent 7890A GC (Agilent Technologies, Colorado Springs, USA) and a BenchTOF-dx mass spectrometer (ALMSCO International, Llantrisant, UK).
HS-SPME of the preheated samples (40 °C, 5 min) was performed under agitation for 1 min at 500 rpm using a 50/30 μm DVB/Carboxen/PDMS stable flexTM fiber (Supelco, Bellefonte, PA, USA), followed by desorption (5 min) at 250 °C onto a 60 m DB-WAX capillary column (0.25 mm i.d. −0.25 μm film thickness). The initial oven temperature was set at 40 °C, held for 5 min, increased to 200 °C at 4 °C min−1, held for 1 min, and finally increased to 260 °C at 8 °C min−1, held for 5 min. The helium flow rate was maintained constant at a flow rate of 1 mL min−1. For quantification purposes, an external calibration method was used. Pyrazine standard solution was prepared by weighing 50 mg of pure standards of methylpyrazine, ethylpyrazine, 2,3-, 2,5- and 2,6-dimethylpyrazine in a 25 mL volumetric flask and make up the rest of the volume with de-ionized water. The 500 mL of standard solutions were added into the vial with 2 g of rye flour and 2.5 mL sodium chloride solution. All analyses were carried out in triplicate injection. Selected ions were used for quantification of the individual components. Compound identification was carried out by injection of commercial standards, by spectra comparison using the Wiley Registry 7th Edition Mass Spectral Library (Wiley and Sons Inc., Weinheim, Germany) and the National Institute Standards and Technology (NIST) 2005 Mass Spectral Library and by calculation of linear retention indexes (LRI) relative to a series of alkanes (C6–C20).
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Publication 2019
Alkanes ARID1A protein, human Buckwheat Capillaries cDNA Library Fibrosis Flour Gas Chromatography-Mass Spectrometry Helium Ions Natural Springs polytetrafluoroethylene-silicone Pyrazines Retention (Psychology) Saline Solution Solid Phase Microextraction Sons
Intact epithelial preparations were as in our published procedures (Ma and Shepherd, 2000 (link)). Wild-type (C57BL/6) or homozygous gene-targeted mice (male or female, 3 to 12 weeks) were deeply anesthetized by injection of ketamine HCl and xylazine (200 mg/kg and 20 mg/kg body weight, respectively) and then decapitated. The head was immediately put into ice-cold Ringer's solution, which contained (in mm) 124 NaCl, 3 KCl, 1.3 MgSO4, 2 CaCl2, 26 NaHCO3, 1.25 NaH2PO4, and 15 glucose (osmolarity, 305 mOsm). The pH was kept at 7.4 by bubbling with 95% O2 and 5% CO2. The nose was dissected out en bloc; the olfactory mucosa attached to the nasal septum and the dorsal recess was removed and kept in oxygenated Ringer. Before use, the entire mucosa was peeled away from the underlying bone and transferred to a recording chamber with the mucus layer facing up. Oxygenated Ringer was continuously perfused at 25 ± 2°C.
The dendritic knobs of OSNs were visualized through an upright differential interference contrast microscope (Olympus; BX51WI) equipped with a charge-coupled device camera (Dage-MTI) and a 40× water-immersion objective. An extra 4× magnification was achieved by an accessory lens in the light path. The GFP- and RFP-tagged cells were visualized under fluorescent illumination. Superimposition of the fluorescent and bright-field images allowed identification of the fluorescent cells under bright field, which directed the recording pipettes (Grosmaitre et al., 2006 (link)). Electrophysiological recordings were controlled by an EPC-10 amplifier combined with Pulse software (HEKA Electronic). Perforated patch-clamp was performed on the dendritic knobs by including 260 μm nystatin in the recording pipette, which was filled with the following solution (in mM): 70 KCl, 53 KOH, 30 methane-sulfonic acid, 5.0 EGTA, 10 HEPES, 70 sucrose; pH 7.2 (KOH), and 310 mOsm. The junction potential was ∼9 mV and was corrected in all experiments off-line. Under voltage-clamp mode, the signals were initially filtered at 10 kHz and then at 2.9 kHz. For voltage-gated ionic currents, the signals were sampled at 50 kHz. For odorant-induced transduction currents (which are slow and long lasting), the signals were sampled at 333 Hz. Further filtering offline at 100 Hz (to remove noise) did not change the response kinetics or amplitudes, indicating that the sampling rate was sufficient and signal aliasing was not a concern. Similarly, under current-clamp mode, the signals were filtered at 2.9 kHz and sampled at 5 kHz. Further filtering off-line at 1.5 kHz did not change the response kinetics or amplitudes.
A seven-barrel pipette was used to deliver stimuli by pressure ejection through a picospritzer (Pressure System IIe; Toohey Company). The stimulus electrode was placed ∼20 μm downstream from the recording site, and both mechanical and odorant responses could be elicited in some neurons (Grosmaitre et al., 2007 (link)). All stimuli were delivered by 138 kPa (20 psi) on the picospritzer. The pulse length was kept at 1 s to ensure that the neurons were stimulated by the intrapipette concentration (Grosmaitre et al., 2006 (link)). Odorants were prepared in 0.5 m solution in dimethylsulfoxide (DMSO) and kept at −20°C. Final solutions were prepared before each experiment by adding Ringer. Odorant mixture Mix 1 contains 19 compounds in equal molar concentration: heptanol, octanol, hexanal, heptanal, octanal, heptanoic acid, octanoic acid, cineole, amyl acetate, (+) limonene, (−) limonene, (+) carvone, (−) carvone, 2-heptanone, anisaldehyde, benzaldehyde, acetophenone, 3-heptanone, and ethyl vanilline. The odorant mixture Mix 2 contained 19 compounds in equal molar concentration: hexanol, nonyl alcohol, nonanal, hexanoic acid, nonanoic acid, valeric acid, ethyl caproate, 1-octen-3-ol, phenethyl alcohol, γ-octanoic lactone, pyrrolidine, methyl anthranilate, benzenethiol (thiophenol), pyridine, pyrazine, geraniol, eugenol, benzyl salicylate, isoamyl acetate. The final concentration of DMSO in the odorant solutions ranges from 0.0002 (v/v) (for a single odorant at 1 μm) to 0.4% (for Mix 1 and Mix 2 at 100 μm). To rule out potential effects of DMSO on electrical responses, we compared the transduction currents in SO–OSNs (n = 6) induced by puffs of Ringer without DMSO or with 0.2–0.5% DMSO; we did not observe any differences. We, therefore, used the Ringer solution as controls in most of the experiments. All compounds and chemicals were obtained from Sigma-Aldrich, unless otherwise stated. Lyral was provided as a generous gift from International Fragrances and Flavors (New York, NY). The peptides AAPD-NRETF and SYFPEITHI were synthesized by Genemed Synthesis, and α-phellandren and β-phenethylamine were purchased from Fluka.
Publication 2009
1-octen-3-ol 2-heptanone acetophenone Acids amyl acetate Anabolism benzaldehyde benzyl salicylate Bicarbonate, Sodium Body Weight Bones caprylic aldehyde carvone Cells Cold Temperature d-Limonene Dendrites Egtazic Acid Electricity Ethanol ethyl-n-butyl ketone ethyl caproate Eucalyptol Eugenol Females Flavor Enhancers Genes geraniol Glucose Head HEPES heptanal Heptanol hexanoic acid Hexanols Homozygote Ion Transport isoamyl acetate Ketamine Hydrochloride Kinetics Lactones Lens, Crystalline Light LINE-1 Elements Lyral Males Medical Devices methanesulfonic acid methyl anthranilate Microscopy, Differential Interference Contrast Molar Mucous Membrane Mucus Mus n-hexanal Neurons nonanal Nose Nystatin octanoic acid Octanols Odorants Olfactory Mucosa Osmolarity p-anisaldehyde pelargonic acid Peptides Phenethylamines Phenylethyl Alcohol Pressure Pulse Rate Pyrazines pyridine pyrrolidine Ringer's Solution Scents Septums, Nasal Sodium Chloride Strains Submersion Sucrose Sulfate, Magnesium Sulfoxide, Dimethyl thiophenol valeric acid Xylazine
After simultaneous gas deposition and photon irradiation, the substrate was warmed up to room temperature to remove volatile species at a ramping rate of 0.2 K min−1, and the formation of solid organic residues was confirmed using FTIR19 (link). The organic residues were dissolved in several tens of microlitres of a water/methanol mixture (1/1 by vol./vol.) and extracted from the reaction substrate using a small amount of quartz wool. The quartz wool with the samples was further transferred into a separate glass vial, and 0.5 ml of H2O was added to the vial. Subsequently, the aqueous solution was collected using a microsyringe and transferred into another glass vial. For an accurate chromatographic baseline resolution when focusing on the target molecules, especially those with nitrogen-containing functional groups (i.e., amide, amino, imino, and N-heterocyclic species; please see the Supplementary Fig. 34), a purification procedure was performed using cation-exchange column chromatography (AG-50W-X8 resin; 200–400 mesh, Bio-Rad Laboratories)39 (link). This pretreatment advantageously eliminates uncharacterised matrix effects to assist with the evaluation of the irradiation products. The purified solution was dried under a gentle nitrogen gas (N2) flow and subsequently dissolved in 50 μl of ultrapure H2O (QToFMS grade from Wako Chemical, Ltd.) before analysis. All glassware and the quartz wool were heated in air at 450 °C for 3 h to prevent contamination by organic compounds.
The sample solution was injected into an orbitrap mass spectrometer (Q Exactive Plus, Thermo Fischer Scientific) with a mass resolution of mm = ~ 140,000 at a mass-to-charge ratio (m/z) of 200 via a high-performance liquid chromatograph (HPLC) system (UltiMate 3000, Thermo Fischer Scientific) equipped with a reversed-phase C18 separation column (1.5 × 250 mm, particle size of 3 μm, InertSustain C18, GL Science) at 40 °C. The eluent program for this HPLC setup is as follows: solvent A (H2O + 0.1% formic acid by volume), solvent B (acetonitrile + 0.1% formic acid by volume) = 100:0 for the initial 5 min, followed by a linear gradient of A:B = 40:60 at 35 min, and it was kept at this ratio for 10 min. The flow rate was 70 μl min−1.
Nucleobases were also analysed using the same HPLC/HRMS equipped with a HypercarbTM separation column (4.6 × 150 mm, particle size of 5 μm, Thermo Fischer Scientific) at 10 °C to verify their presence in the sample. The eluent program is as follows: at t = 0, solvent A (20 mM nonafluoropentanoic acid in distilled water + 0.1% formic acid (dissolved)), solvent B (acetonitrile + 0.1% formic acid (dissolved)) = 100:0, followed by a linear gradient of A:B = 40:60 at t = 60 min and it was kept at this ratio for 10 min. The flow rate was 0.2 ml min−1. The detailed analytical conditions of the HPLC system have been described previously25 (link),40 (link).
The identification of nitrogen-bearing molecules was based on a co-injection analysis in which the analyte sample and standard reagent solutions were analysed as part of the same HPLC/HRMS run.
For sugar molecules, we analysed the organic residues without the cation-exchange chromatography purification procedure (cf. this section for amide, amino, imino, and N-heterocyclic species). The mass spectra were recorded in the positive electrospray ionisation (ESI) mode for the nucleobases, other nitrogen heterocycles, dipeptides, and amino acids with an m/z range of 50–400 and a spray voltage of 3.5 kV. To analyse the sugars, the mass spectra were recorded in the negative ESI mode with an m/z range of 50−215 and a spray voltage of 3.0 kV. The capillary temperature of the ion transfer was 300 °C. The injected samples were vaporised at 300 °C. We set up an inverse gradient program to maintain the ionisation efficiency during the ESI. To minimise analytical noise and the background signals in the liquid chromatography (LC) and orbitrap mass spectrometry (MS), we used high purity grade water and acetonitrile (LC/MS grade from Wako Chemical, Ltd.). Under these experimental conditions, the mass precision is always better than 3 ppm for each chromatogram (e.g. 113.0348 ± 0.0003 for protonated uracil). The same volume of distilled water was measured to validate the contamination level of the MS; no prebiotic molecules were detected during the analytical blank measurement. For another sample (processed as described earlier in this paragraph), when no gases were deposited (i.e., UV photons only) on the substrate, we found that no prebiotic molecules formed (Supplementary Fig. 7), further confirming the blank control. Standard reagent grade target molecules were used and amino acids were purchased from Wako Chemicals, Ltd. and Sigma-Aldrich, Ltd. Pyrimidine and purine nucleobases and other nitrogen heterocycles were purchased from Tokyo Chemical Industry, Ltd. and Sigma-Aldrich, Ltd., and dipeptides were from AnaSpec, Inc. and PH Japan, Ltd. Dihydrouracil was synthesised in our laboratory from reagent grade β-alanine and potassium cyanate (both from Wako Chemicals, Ltd.), according to the method reported by Dakin41 . The target molecules (standards) were dissolved in distilled H2O, and a mixture of the solution was analysed using the aforementioned procedure. To prevent misidentification, structural isomers were not analysed during the same run; e.g., to identify pyrimidine and its isomers (pyridazine and pyrazine), we performed three independent analyses.
After the analyses of the standard reagents and the sample in a separate run when the C18 column was used, 1 μl (5 μl when the HypercarbTM was used) of the sample solution was co-injected with 1 μl (2 μl for the HypercarbTM) of a mixture of the standard reagents. The concentration of the co-injected solution was adjusted to not significantly exceed the sample peak heights. Eddhif et al.27 (link) identified various prebiotic molecules based on a comparison of the retention times of their target molecules on a separation column. Although this method is appropriate when the number of peaks in the mass chromatogram is not high, it becomes unsuitable when a number of peaks appear very close to each other. Moreover, the co-injection analysis is not always able to identify molecules in a mass chromatogram due to an insufficient separation of peaks and/or the absence of an appropriate chemical reagent. In this case, analysis of the sample using a different separation column on the HPLC/HRMS would be ideal to firmly identify a target molecule in a mixture of complex organic molecules. In the present study, we identified pyrimidine nucleobases by using two different separation columns (C18 and HypercarbTM) and the yields that were estimated under the two different conditions were consistent with each other, which strongly supports our conclusion that pyrimidine nucleobases are actually present in the sample. In contrast, under the present analytical conditions, purine nucleobases, except for hypoxanthine, were not eluted from the HypercarbTM separation column probably due to the strong interaction between nucleobases and the stationary phase of the column; their detection was successful when the C18 column was used as a separation column. Hence, the cross-validation analysis is a promising approach to better understand the molecular compositions in complex organic residues.
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Publication 2019
acetonitrile Amides Amino Acids beta-Alanine Capillaries Carbohydrates Chromatography Complex Mixtures dihydrouracil Dipeptides formic acid Gases High-Performance Liquid Chromatographies Hypoxanthine Isomerism Liquid Chromatography Mass Spectrometry Methanol Nitrogen Organic Chemicals perfluoropentanoic acid potassium cyanate Prebiotics purine Pyrazines pyridazine Pyrimidines Quartz Radiotherapy Resins, Plant Retention (Psychology) Solvents Sugars Tetranitrate, Pentaerythritol Uracil

Most recents protocols related to «Pyrazines»

Example 11

[Figure (not displayed)]

Step a: To a stirred suspension of 2,4-dichloro-6-methyl-3-nitropyridine (2.5 g, 12 mmol) in 24 mL of THE was added a solution of 7N NH3 in MeOH (14 mL, 98 mmol). After stirring for 3 h, the volatiles were removed in vacuo. The crude residue was purified by silica gel column chromatography to give 2-chloro-6-methyl-3-nitropyridin-4-amine. C6H7CN3O2 [M+H]+ 188.0, found 188.0.

Step b: To a stirred mixture of 2-chloro-6-methyl-3-nitropyridin-4-amine (760 mg, 4.1 mmol) and Fe (1.1 g, 20 mmol) in a 5:1 solution of EtOH/H2O (24 mL) was added 4.4 mL of conc. HCl. The contents were refluxed for 30 min, then cooled to room temperature and quenched with 100 mL of sat. NaHCO3 (aq). The mixture was extracted with EtOAc and the combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo to yield 2-chloro-6-methylpyridine-3,4-diamine. MS: (ES) m/z calculated for C6H9ClN3 [M+H]+ 158.0, found 158.0.

Step c: To a stirred solution of 2-chloro-6-methylpyridine-3,4-diamine (0.49 g, 3.1 mmol) in 3 mL of EtOH was added a 40% w/w aqueous solution of glyoxal (2.0 mL, 12 mmol). After refluxing for 16 h, the mixture was diluted with H2O and extracted with EtOAc. The organic layers were combined, dried over MgSO4, filtered and concentrated in vacuo. The crude residue was purified by silica gel column chromatography to give 5-chloro-7-methylpyrido[3,4-b]pyrazine. MS: (ES) m/z calculated for C8H7ClN3 [M+H]+ 180.0, found 180.1.

Step d: To a stirred solution of 5-chloro-7-methylpyrido[3,4-b]pyrazine (200 mg, 1.0 mmol) and 2′-chloro-2-methyl-3′-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1′-biphenyl]-3-amine (350 mg, 1.0 mmol) in 2 mL of MeCN was added AcOH (0.18 mL, 3.1 mmol). After 30 min, the volatiles were concentrated in vacuo. The crude residue was purified by silica gel column chromatography to give N-(2′-chloro-2-methyl-3′-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1′-biphenyl]-3-yl)-7-methylpyrido[3,4-b]pyrazin-5-amine. MS: (ES) m/z calculated for C27H29BClN4O2 [M+H]+ 487.2, found 487.2.

Step e: To a stirred solution of N-(2′-chloro-2-methyl-3′-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1′-biphenyl]-3-yl)-7-methylpyrido[3,4-b]pyrazin-5-amine (390 mg, 0.66 mmol), 6-chloro-2-methoxynicotinaldehyde (240 mg, 1.4 mmol), and K3PO4 (490 mg, 2.3 mmol) in a 1:1 solution of 1,4-dioxane/H2O (3.3 mL) under N2 (g) was added Pd(PPh3)4 (76 mg, 0.066 mmol). The mixture was stirred under N2 (g) at 90° C. for 3 h. The mixture was diluted with H2O and then extracted with EtOAc. The combined organic layers were dried over MgSO4, filtered, and concentrated. The crude residue was purified by silica gel column chromatography to give 6-(2-chloro-2′-methyl-3′-((7-methylpyrido[3,4-b]pyrazin-5-yl)amino)-[1,1′-biphenyl]-3-yl)-2-methoxynicotinaldehyde. MS: (ES) m/z calculated for C28H23ClN5O2 [M+H]+ 496.2, found 496.2.

Step f: To a stirred mixture of 6-(2-chloro-2′-methyl-3′-((7-methylpyrido[3,4-b]pyrazin-5-yl)amino)-[1,1′-biphenyl]-3-yl)-2-methoxynicotinaldehyde (120 mg, 0.25 mmol), (S)-5-(aminomethyl)pyrrolidin-2-one hydrochloride (150 mg, 0.99 mmol), and trimethylamine (0.14 mL, 0.99 mmol) in a 4:1 solution of DCM/MeOH (5 mL) was added NaBH(OAc)3 (530 mg, 2.5 mmol). After stirring for 30 min, the mixture was filtered through Celite, and the filtrate was concentrated in vacuo. The product was purified by preparative HPLC to give the product (S)-5-((((6-(2-chloro-2′-methyl-3′-((7-methylpyrido[3,4-b]pyrazin-5-yl)amino)-[1,1′-biphenyl]-3-yl)-2-hydroxypyridin-3-yl)methyl)amino)methyl)pyrrolidin-2-one. 1H NMR (400 MHz, DMSO-d6) δ 12.59 (s, 1H), 9.32 (s, 1H), 9.07 (d, J=2.0 Hz, 1H), 8.86 (d, J=2.0 Hz, 1H), 8.23 (d, J=8.7 Hz, 1H), 7.76 (d, J=7.0 Hz, 1H), 7.62 (s, 1H), 7.55 (d, J=7.5 Hz, 1H), 7.50-7.43 (m, 1H), 7.35 (dd, J=7.9, 7.9 Hz, 1H), 7.12 (s, 1H), 6.96 (d, J=7.5 Hz, 1H), 6.55 (s, 2H), 6.43 (d, J=7.1 Hz, 1H), 4.07 (s, 3H), 3.95-3.84 (m, 1H), 2.48 (s, 4H), 2.26-2.15 (m, 3H), 2.11 (s, 3H), 1.86-1.70 (m, 1H). MS: (ES) m/z calculated for C32H31ClN7O2 [M+H]+ 580.2, found 580.1.

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Patent 2024
1H NMR 2-picoline 4-nitropyridine Amines Bicarbonate, Sodium Celite Chromatography Diamines Dioxanes diphenyl Ethanol Gel Chromatography Glyoxal High-Performance Liquid Chromatographies Pyrazines Silica Gel Silicon Dioxide Sulfate, Magnesium Sulfoxide, Dimethyl trimethylamine

Example 75

[Figure (not displayed)]

To a stirred solution of 3-(chlorodifluoromethyl)-6-(6-(3,3-difluorocyclobutoxy)-5-fluoropyridin-3-yl)-[1,2,4]triazolo[4,3-a]pyrazine (150 mg, 0.34 mmol)) in MeCN (7.5 mL) was added Cs2CO3 (668 mg, 2.06 mmol) and ethanol (0.2 mL, 3.4 mmol). The reaction mixture was stirred for 1 h at room temperature. The reaction mixture was treated with water (20.0 mL) and extracted with ethyl acetate (2×25 mL). The organic layer was washed with brine (20 mL), dried over anhydrous Na2SO4 and concentrated. The crude compound was purified by preparative HPLC to afford a solid (22 mg, 0.05 mmol, 15% yield). Prep. HPLC method: Rt 13.1; Column: XBridge C-18 (150×19 mm), 5.0 μm; Mobile phase: 0.1% TFA in water/acetonitrile; Flow Rate: 15.0 mL/min. HPLC: Rt 5.08 min, 94.8% Column: XBridge C8 (50×4.6) mm, 3.5 μm Mobile phase: A: 0.1% TFA in water, B: 0.1% TFA in ACN; Flow Rate: 2.0 mL/min. LCMS: 416.1 (M+H), Rt 2.44 min, Column: ZORBAX XDB C-18 (50×4.6 mm), 3.5 μm Mobile Phase: A: 0.1% HCOOH in water:ACN (95:5), B: ACN; Flow Rate: 1.5 mL/min. 1H NMR (400 MHz, CD3OD): δ 9.54 (d, 1H), 8.83 (d, 1H), 8.67 (d, 1H), 8.26 (dd, 1H), 5.32-5.30 (m, 1H), 4.40 (q, 2H), 3.25-3.15 (m, 2H), 2.90-2.77 (m, 2H), 1.49 (t, 3H).

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Patent 2024
1H NMR acetonitrile brine Ethanol ethyl acetate High-Performance Liquid Chromatographies Lincomycin Pyrazines
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Example 47

[Figure (not displayed)]

A mixture of 6-chloro-3-(methoxymethyl)-[1,2,4]triazolo[4,3-a]pyrazine (150 mg, 0.76 mmol), 3-fluoro-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-(2,2,2-trifluoro-1,1-dimethyl-ethoxy)pyridine (527.36 mg, 1.51 mmol), Cs2CO3 (738.18 mg, 2.27 mmol), Pd(dppf)Cl2 (110.52 mg, 0.15 mmol) in 1,4-Dioxane (8 mL) and water (0.80 mL) was stirred at 75° C. for 9 hours under N2. After cooling to room temperature, the mixture was diluted with H2O (20 mL), and the mixture was extracted with EtOAc (30 mL×2). The combined organic phase was washed with water (30 mL×1) and brine (30 mL), dried over Na2SO4, filtered and concentrated to give the crude product. The crude product was purified by Prep-HPLC (Boston Prime C18 (150 mm×30 mm, 5 μm), A=H2O (0.05% NH4OH) and B=CH3CN; 49-59% B over 9 minutes) to give the product (90.56 mg, 235 μmol, 31% yield) as a solid. 1H NMR (CDCl3, 400 MHz) δH=9.43 (s, 1H), 8.57-8.40 (m, 2H), 8.01 (d, 1H), 5.13 (s, 2H), 3.46 (s, 3H), 1.88 (s, 6H). LCMS Rt=1.24 min in 2.0 min chromatography, 10-80AB, MS ESI calcd. C16H16F4N5O2 [M+H]+ 386.1 found 386.1.

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Patent 2024
1H NMR brine Chromatography Dioxanes High-Performance Liquid Chromatographies Lincomycin Pyrazines pyridazine pyridine
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Example 25

[Figure (not displayed)]

A mixture of 3-[chloro(difluoro)methyl]-6-[5-fluoro-6-[(1R)-2,2,2-trifluoro-1-methyl-ethoxy]-3-pyridyl]-[1,2,4]triazolo[4,3-a]pyrazine (500 mg, 1.21 mmol) and AgOTf (3120.55 mg, 12.15 mmol) in Ethanol (7 mL) and MeCN (7 mL) was stirred at 90° C. for 5 days. The mixture was cooled to room temperature then EtOAc (20 mL) and brine (50 mL) were added to the mixture, the resulting suspension was filtered through Celite. The filtrate was separated and the aqueous phase was extracted with EtOAc (50 mL). The combined organic phase was dried over anhydrous Na2SO4, filtered and concentrated to give the crude product. The crude product was purified by chromatography flash on silica gel (EtOAc in PE=10% to 30% to 50%) and then triturated from DCM (3 mL) and n-hexane (4 mL) to give the product (31.35 mg, 74 μmol, 6% yield) as a solid. 1H NMR (CDCl3, 400 MHz) δH=9.52 (d, 1H), 8.48 (dd, 2H), 8.04 (dd, 1H), 5.95-5.87 (m, 1H), 4.37 (q, 2H), 1.60 (d, 3H), 1.51 (t, 3H). LCMS Rt=1.35 min in 2 min chromatography, 10-80AB, MS ESI calcd. for C16H14F6N5O2 [M+H]+ 422.1. found 422.1.

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Patent 2024
1H NMR brine Celite Chromatography Ethanol Lincomycin n-hexane Pyrazines Silica Gel

Example 79

[Figure (not displayed)]

To a stirred solution of 3-(chlorodifluoromethyl)-6-(6-(2,2,2-trifluoroethoxy)pyridin-3-yl)-[1,2,4]triazolo[4,3-a]pyrazine (190 mg, 0.50 mmol)) in MeCN (10.0 mL) was added Cs2CO3 (978 mg, 3.0 mmol) and ethanol (0.58 mL, 10 mmol) at room temperature and stirred for 3 hours. The reaction mixture was treated with water (15 mL) and extracted with ethyl acetate (2×20 mL). The organic layer was washed with brine (15 mL), dried over anhydrous Na2SO4 and concentrated. The crude compound was purified by preparative HPLC to afford a solid (10 mg, 0.025 mmol, 5.1% yield. Prep-HPLC method: Rt 9.35; Column: XBridge (150×19 mm), 5.0 μm; 0.1% TFA in water/acetonitrile; Flow Rate: 15.0 mL/min. HPLC: Rt 4.89 min, Column: XBridge C8 (50×4.6) mm, 3.5 μm Mobile phase: A: 0.1% TFA in water, B: 0.1% TFA in ACN; Flow Rate: 2.0 mL/min. LCMS: 390.0 (M+H), Rt 2.70 min, Column: Atlantis dC-18 (50×4.6 mm), 5 μm Mobile Phase: A: 0.1% HCOOH in water:ACN (95:5), B: ACN; Flow Rate: 1.5 mL/min 1H NMR (400 MHz, CDCl3): δ 9.54 (d, 1H), 8.74 (d, 1H), 8.48 (d, 1H), 8.26 (dd, 1H), 7.06 (d, 1H), 4.87 (q, 2H), 4.38 (q, 2H), 1.52 (t, 3H).

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Patent 2024
1H NMR acetonitrile brine Ethanol ethyl acetate High-Performance Liquid Chromatographies Lincomycin Pyrazines

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Pyrazine is a heterocyclic organic compound with the chemical formula C4H4N2. It is a colorless, volatile liquid with a characteristic odor. Pyrazine serves as a building block in the synthesis of various pharmaceutical and agricultural products, as well as in the production of dyes and other industrial chemicals.
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More about "Pyrazines"

Pyrazines are a class of heterocyclic aromatic nitrogen-containing compounds with a wide range of applications.
These versatile molecules are found naturally and have been studied for their potential therapeutic uses in areas like cancer, inflammation, and neurological disorders.
Understanding the synthesis and properties of pyrazines is crucial for researchers in organic chemistry, food science, and medicinal chemistry.
The PubCompare.ai platform can enhance pyrazine research by providing access to the best protocols from literature, preprints, and patents.
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This leads to more efficient and effective research outcomes.
Some related terms and subtopics include: N-heterocyclic compounds, aromatic heterocycles, nitrogen-containing rings, flavoring agents, fragrance compounds, pharmaceutical intermediates, biological activities, 2,6-dimethylpyrazine, benzaldehyde, hexanal, ethanol, Prep-HPLC, Millex-LCR, Gemini C18, XBridge C18, and Boston Prime C18.
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