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tert-butyl N-(3-trifluoromethylpyrazin-2-yl)carbamate[ No CAS ]
[ 213019-67-1 ]
Yield
Reaction Conditions
Operation in experiment
0.48 g
With trifluoroacetic acid; In 1,2-dichloro-ethane; for 2.0h;Reflux;
Trifluoroacetic acid (1 .1 ml, 14mmol) was added in portions to a stirred solution of the tert-butyl N-(3-trifluoromethylpyrazin-2-yl)-carbamate (0.92g, ca. 3.5mmol) in 1 ,2- dichlorethane (9.2ml) at room temperature. The resulting mixture was heated under reflux for 2 hours, allowed to cool, then washed with saturated aqueous sodium bicarbonate and dried through a phase-separation filter. Concentration under reduced pressure then gave 3-trifluoromethyl-2-aminopyrazine (0.48g) as a yellow solid. 1H NMR (400MHz, CDCI3) delta 8.25 (s,1 H), 8.00 (s, 1 H), 5.15 (br s, 2H)
0.48 g
With trifluoroacetic acid; In 1,2-dichloro-ethane; for 2.0h;Reflux;
Trifluoroacetic acid (1.1 ml, 14mmol) was added in portions to a stirred solution of tert-butyl N-(3-trifluoromethylpyrazin-2-yl)-carbamate (0.92g, ca. 3.5mmol) in 1 ,2- dichlorethane (9.2ml) at room temperature. The resulting mixture was heated under reflux for 2 hours, allowed to cool, then washed with saturated aqueous sodium bicarbonate and dried through a phase-separation filter. Concentration under reduced pressure then gave 3-trifluoromethyl-2-aminopyrazine (0.48g) as a yellow solid. 1H NMR (400 MHz, CDCI3) delta 8.25 (s, 1 H), 8.00 (s, 1 H), 5.15 (br s, 1 H).
0.48 g
With trifluoroacetic acid; In 1,2-dichloro-ethane; for 2.0h;Reflux;
Trifluoroacetic acid (1.lml, l4mmol) was added in portions to a stirred solution of the crude tert-butyl N-(3-trifluoromethylpyrazin-2-yl)-carbamate (0.92g, ca. 3.5mmol) in 1 ,2-dichlorethane (9.2m1) at room temperature. The resulting mixture was heated under reflux for 2 hours, allowed to cool, then washed with saturated aqueous sodium bicarbonate and dried through a phase-separation filter. Concentration under reducedpressure then gave 3-trifluoromethyl-2-aminopyrazine (0.48g) as a yellow solid1H NMR (400 MHz, CDCI3)5 8.25 (s, 1H), 8.00 (s, 1H), 5.15 (brs, 1H).
With pyridine; bromine; In dichloromethane; chloroform; at 20.0℃; for 24.0h;
A solution of bromine in dichloromethane (10ml) was added in portions to a stirred solution of <strong>[213019-67-1]2-amino-3-trifluoromethylpyrazine</strong> (1.5g, 9.2mmol) and pyridine (0.90ml, 1 1 mmol) in chloroform. The resulting mixture was stirred at room temperature for 24 hours. Volatiles were removed under reduced pressure and the residue was purified by chromatography on silica gel using a gradient of ethyl acetate in isohexane as eluent to give 2-amino-3-trifluoromethyl-5-bromopyrazine (1 .7g, 77%) as an off-white solid. (0286) 1H NMR (400MHz, CDCI3) delta 8.30 (s, 1 H), 5.13 (br s, 2H).
77%
With pyridine; bromine; In dichloromethane; chloroform; at 20.0℃; for 24.0h;
A solution of bromine in dichloromethane (1 OmI) was added in portions to a stirred solution of <strong>[213019-67-1]2-amino-3-trifluoromethylpyrazine</strong> (1 .5g, 9.2mmol) and pyridine (0.90m1, limmol) in chloroform. The resulting mixture was stirred at room temperature for 24hours. Volatiles were removed under reduced pressure and the residue was purified by chromatography on silica gel using a gradient of ethyl acetate in isohexane as eluent to give 2-am ino-3-trifluoromethyl-5-bromopyrazine (1 .7g, 77% yield) as an off-white solid.1H NMR (400 MHz, CDCI3)5 8.30 (s, 1H), 5.13 (br s, 2H).
58.1%
With N-Bromosuccinimide; In dichloromethane; at 20.0℃; for 15.0h;
[1388] A solution of <strong>[213019-67-1]3-(trifluoromethyl)pyrazin-2-amine</strong> (0.075 g, 0.460 mmol) [Oakwood, 500509] in dichloromethane (1.88 mL) was treated with N-bromosuccinimide (0.082 g, 0.460 mmol) and stirred at rt for 15 h. The reaction mixture was treated with additional N-bromosuccinimide (0.041 g, 0.230 mmol) and stirred for 21 h. The reaction mixture was diluted with water (10 mL) and extracted with dichloromethane (220 mL). The combined organic extracts were dried over sodium sulfate, filtered, and concentrated to brown, oily-solid. Purification by flash column chromatography using EtOAc in hexanes (0% to 30%) gave the desired product (64.5 mg, 58.1%) as a white solid. LCMS for C5H4BrF3N3(M+H)+: m/z=242.0, 243.9; Found: 241.9, 243.9.
44%
With N-Bromosuccinimide; In dichloromethane;
To <strong>[213019-67-1]3-(trifluoromethyl)pyrazin-2-amine</strong> (0.020 g, 0.12 mmol, Oakwood) in CH2Cl2 (0.5 mL) was added N-bromosuccinimide (0.022 g, 0.12 mmol) and the reaction was stirred overnight. The reaction mixture was partitioned between DCM and water, and the aqueous portion was extracted with three portions of DCM. The combined organic extracts were dried over Na2SO4, filtered, and concentrated. The product was purified by flash chromatography, eluting with a gradient from 0-25% EtOAc in hexanes to afford a white crystalline solid (0.013 g, 44%). 1H NMR (400 MHz, CDCl3) delta 8.44-8.23 (s, 1H), 5.22-4.98 (s, 2H). 19F NMR (376 MHz, CDCl3) delta -65.04--69.69 (s).
2-amino-3-trifluoromethyl-5-iodopyrazine[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
44%
With N-iodo-succinimide; trifluoroacetic acid; In acetonitrile; at 20.0℃; for 18.0h;
N-lodosuccinimide (3.4g, 15mmol) was added to a stirred suspension of 2-amino-3- trifluoromethylpyrazine (1 .63g, 10mmol) and trifluoroacetic acid (340mg, 3mmol) in acetonitrile (20ml) at room temperature. After stirring at room temperature for another 18 hours, the mixture was filtered. The filtrate was diluted with ethyl acetate and washed with a saturated aqueous solution of sodium thiosulfate. The organic layer was dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using petroleum ether/ethyl acetate = 5:1 as eluent to give 2-amino-3-trifluoromethyl-5-iodopyrazine (1.27g, 44%) as a yellow solid. (0278) 1H NMR (300Mz, DMSO-d6): delta 8.48 (s, 1 H), 7.06 (br s, 2H).
With bromine; potassium hydroxide; In water; at 90.0℃; for 3.0h;
Bromine (3.2g, 20mmol) was added dropwise to a stirred solution of potassium hydroxide (3.4g, 60mmol) in water (30ml) at 0C. 3-Trifluoromethylpyrazine-2-carboxamide (1.9g, l Ommol) was then added to the solution and the mixture was heated at 90C for 3h. The resulting mixture was poured into water and extracted with ethyl acetate. The organic extracts were washed with brine, dried over Na2S04 and evaporated under reduced pressure. The residue was purified by chromatography on silica gel using petroleum ether/ethyl acetate = 3:1 as eluent to afford 2-amino-3-trifluoromethylpyrazine (1 .01 g, 62%). (0275) 1H NMR (300Mz, CDCI3) delta 8.21 (d, 1 H), 8.01 (d, 1 H), 5.1 1 (br s, 2H)
tert-butyl N-(3-trifluoromethylpyrazin-2-yl)carbamate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
With diphenylphosphoranyl azide; triethylamine; In toluene; at 90℃; for 4h;
Diphenylphosphoryl azide (3.47g, 12.6mmol) was added to a stirred solution of 3- trifluoromethylpyrazine-2-carboxylic acid (1 .92g, 9.7Ommol) and triethylamine (1 .28g, 12.6mmol) in tert-butanol (9.6m1, lOOmmol) and toluene (19.2m1). The resulting mixturewas heated at 90C for 4 hours and then allowed to cool. It was washed with 2M aqueous sodium bicarbonate, then dried through a phase-separation filter and concentrated under reduced pressure. The residue was purified by chromatography on silica gel using a gradient of ethyl acetate in hexane as eluent to give tert-butyl N-(3-trifluoromethylpyrazin- 2-yl)-carbamate containing 3-trifluoromethyl-2-aminopyrazine (2.Og) as a colourless oilwhich slowly crystallised to give a white solid. 1H NMR (400 MHz, CDCl3) 8.70 (s, 1H),8.40 (s, 1H), 7.20 (brs, 1H), 1.55 (s, 9H).
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