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To a flask fitted with overhead stirrer, condenser, thermometer and nitrogen line was added <strong>[369638-68-6]tert-butyl (5-methylpyrazin-2-yl)carbamate</strong> (1.0 eq), and water (6.85 vols). The mixture was heated to 70 C. and trifluoroacetic acid (TFA) (1.2 eq) was added slowly drop-wise over 90-120 minutes. Water (0.22 vols) was added to wash the TFA into the flask. The reaction mixture was heated at 65-75 C. for at least 30 minutes, and then cooled to 15-25 C. Then 32% w/w sodium hydroxide (1.30 eq) was added drop-wise over 30-60 minutes maintaining the reaction temperature between 15-40 C. Water (0.22 vols) was added to wash the sodium hydroxide into the flask. N-Propylacetate (7.0 vols) was added and the mixture agitated for 45 minutes at 20 C. The layers were separated, the organic layer was retained and the aqueous layer was returned to the flask. N-Propylacetate (7.0 vols) was added and the mixture agitated for 45 minutes at 20 C. The layers were separated, the organic layer was retained and the aqueous layer was returned to the flask. This process was repeated twice. The combined organic layers were filtered through a filter containing silica (20% w/w) into a clean dry flask. The mixture was heated to 40 C. and then vacuum distilled to a final volume of 1.0-1.33 vols. Toluene (3.0 vols) was added, and the vacuum distillation continued at 40 C. to a final volume of 1.0-1.33 vols. This process was repeated twice. The resulting mixture was cooled to 5 C., and agitated for 1 hour at this temperature then filtered, washed with toluene (0.3 vols) at 0-5 C. The batch is slurry washed with toluene (1.0 vol) at 0-5 C. After drying at 45 C. overnight, the desired product was obtained as a solid (corrected yield typically 75%). 1H NMR delta (400 MHz CDCl3): 7.92 (s, 1H), 7.87 (s, 1H), 4.6 (bs, 2H), 2.40 (s, 3H)
74%
A. 5-methylpyrazin-2-amine; To a solution <strong>[369638-68-6]tert-butyl 5-methylpyrazin-2-ylcarbamate</strong> (1.5 g, 7.17 mmol) in CH2CI2 (20 ml) was added TFA (2.6 mL, 35.86 mmol). The reaction mixture was stirred for 4 hours at room temperature after which, it was concentrated under reduced pressure. The reaction mixture was diluted with CH2CI2 and neutralized with sai.NaHCOs solution. The organic layer was separated and the aqueous layer was extracted with CH2CI2. The combined organic extracts were washed with brine, dried over MgS04, celite filtered and concentrated under reduced pressure. The crude product was purified by flash chromatography using (30% to 50% Ethyl acetate/Hexane) as a solvent to afford title compound (580 mg, 74% yield). MS m/z : 110 [M+l] .
With sodium carbonate; In dichloromethane;
Step 2: 5-Methyl-2-aminopyrazine. To a stirred solution of <strong>[369638-68-6](5-methyl-pyrazin-2-yl)-carbamic acid tert-butyl ester</strong> (2.1 g, 10 mmol) in 30 mL CH2Cl2 at 0 C. under nitrogen was added trifluoroace (30 mL). The solution was allowed to warm to RT overnight. The solution was rotary evaporated to remove TFA and the residue was redissolved in 200 mL CH2Cl2 and stirred with 100 mL 10% Na2CO3. The organics were isolated and the aqueous solution extracted 3*100 mL with CH2Cl2. The organics were combined, dried (MgSO4), filtered and concentrated to an orange solid (1 g, 92%). 1H-NMR (400 MHz, CDCl3) delta8.46 (s, 1H), 7.70 (s, 1H), 2.49 (s, 3H).
Example 76; (3R)-1-{2-[(5-Methylpyrazin-2-yl)amino]-2-oxoethyl}-3-[2-piperidin-1-yl-2-(2-thienyl)propanoyl]oxy}-1-azoniabicyclo[2.2.2]octane bromide (Isomer 1); a) 2-Bromo-N-(5-methylpyrazin-2-yl)acetamide; tert-Butyl 5-methylpyrazin-2-ylcarbamate (2.4 g) was heated in hydrochloric acid (50 mL) at 50 C. for 30 min. The brown solution was cooled to RT and made basic by addition of solid sodium carbonate. The products were then extracted with ethyl acetate (2×100 mL) and dried over magnesium sulfate. Concentration of the extracts gave a crude solid. The solid was dissolved in dry DMF (30 mL) and cesium carbonate (11.21 g) added. To the stirred mixture was added bromoacetylbromide and the mixture stirred at RT for 2 h. Water (200 mL) was added, and the mixture extracted with ethyl acetate (2×100 mL). Concentration of the extract to 50 mL and addition of isohexane (100 mL) gave the subtitled compound as a solid (1.640 g).1H NMR (400 MHz, DMSO) delta 11.06 (1H, s), 9.17 (1H, s), 8.31 (1H, d), 4.16 (2H, s), 2.46 (3H, s).
With trifluoroacetic acid; In dichloromethane; at 20℃;Cooling with ice;
tert-butyl 5-methylpyrazin-2-yl carbamate (6.27 g, 30.0 mmol) was weighed and dissolved in 30 mL dichloromethane, and in an ice water bath, 20 mL trifluoroacetic acid was added slowly. It was moved to react at room temperature for 1 hour, rotate evaporated to dryness to remove the solvent, and was used for the next step directly.
With trifluoroacetic acid; In dichloromethane; at 20℃; for 1.0h;Cooling with ice;
tert-butyl 5-methylpyrazin-2-yl carbamate (6.27 g, 30.0 mmol) was weighed and dissolved in 30 mL dichloromethane, and in an ice water bath, 20 mL trifluoroacetic acid was added slowly. It was moved to react at room temperature for 1 hour, rotate evaporated to dryness to remove the solvent, and was used for the next step directly.
5-Methylpyrazin-2-amine To a flask fitted with overhead stirrer, condenser, thermometer and nitrogen line was added <strong>[369638-68-6]tert-butyl (5-methylpyrazin-2-yl)carbamate</strong> (1.0 eq), and water (6.85 vols). The mixture was heated to 70 C. and trifluoroacetic acid (TFA) (1.2 eq) was added slowly drop-wise over 90-120 minutes. Water (0.22 vols) was added to wash the TFA into the flask. The reaction mixture was heated at 65-75 C. for at least 30 minutes, and then cooled to 15-25 C. Then 32% w/w sodium hydroxide (1.30 eq) was added drop-wise over 30-60 minutes maintaining the reaction temperature between 15-40 C. Water (0.22 vols) was added to wash the sodium hydroxide into the flask. N-Propylacetate (7.0 vols) was added and the mixture agitated for 45 minutes at 20 C. The layers were separated, the organic layer was retained and the aqueous layer was returned to the flask. N-Propylacetate (7.0 vols) was added and the mixture agitated for 45 minutes at 20 C. The layers were separated, the organic layer was retained and the aqueous layer was returned to the flask. This process was repeated twice. The combined organic layers were filtered through a filter containing silica (20% w/w) into a clean dry flask. The mixture was heated to 40 C. and then vacuum distilled to a final volume of 1.0-1.33 vols. Toluene (3.0 vols) was added, and the vacuum distillation continued at 40 C. to a final volume of 1.0-1.33 vols. This process was repeated twice. The resulting mixture was cooled to 5 C., and agitated for 1 hour at this temperature then filtered, washed with toluene (0.3 vols) at 0-5 C. The batch is slurry washed with toluene (1.0 vol) at 0-5 C. After drying at 45 C. overnight, the desired product was obtained as a solid (corrected yield typically 75%). 1H NMR delta (400 MHz CDCl3): 7.92 (s, 1H), 7.87 (s, 1H), 4.6 (bs, 2H), 2.40 (s, 3H)
With sodium hydroxide; In aq. phosphate buffer; at 85℃; for 24h;pH 7.4;
Pyrazine derivatives were synthesized from a one-pot reaction, in which 1,3-dihydroxyacetone, glycolaldehyde, and 2-aminoacetamidine-dihydrobromide (0.10 M 1:1:1 ratio) were mixed in aqueous solution with sodium phosphate (0.25 M) atpH 7.4 by addition of NaOH, then heated to 85 C for 24 h. In a2-mL microvial, reaction contents were de-aerated and purged with nitrogen before being sealed under vacuum. A 1.0 mL aliquot of the product mixture was diluted with 8 mL of water,and a 5 mL portion was then desalted on a 20 mL Discovery DSC-18 column (Supelco, Bellefonte, PA, USA). Material was eluted with 36 mL water and 44 mL 50% methanol/water, collected in 20 separate fractions. Salt-free fractions 10-20(from 37-80 mL eluent) were combined and concentrated to 0.5 mL syrup using a CentriVap centrifuge. After storage at -20 C, the mixture was suspended in 200 μL water, and 50 μL aliquots were further diluted in 300 μL water for adequate ampoule sampling volume.
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