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EXAMPLE 2 Preparation of 3-Amino-5,6-dibromopyrazinethiol Aminotribromopyrazine was prepared, by the same procedure reported for the trichloro analog, from tetrabromopyrazine. Using the same procedure as above, 30 g. of <strong>[66490-61-7]aminotribromopyrazine</strong>, and 24 g. of sodium sulfide nonohydrate in 500 IPA gave 13.5 g. (53% yield) of the desired compound. Anal. Calcd. for C4 H3 Br2 N3 S: C, 16.86; H, 1.06; N, 14.74. Found: C, 17.55; H, 1.21; N, 14.89.
With N-Bromosuccinimide; In tetrahydrofuran; at 0 - 21℃; for 12.0833h;
General procedure: [0267] 6-bromopyrazin-2-amine (5.00 g 1.0 equiv.) was dissolved in dry THF (15 mL) at 0 C, NBS (20 g 2.2 equiv.) was added and stirred for 5 min. The reaction was allowed to warm to room temperature and stirred for 12 h. The solvent was evaporated under reduced pressure and the residue was extracted with ethyl acetate and sodium thiosulfate. The organic layer was then washed with water and brine. The combined organic layer was dried over sodium sulfate, filtered and concentrated. The product was purified via silica gel chromatography (ethyl acetate:hexanes).
3-fluoro-N-(3,5,6-tribromopyrazin-2-yl)benzamide[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
57%
With dmap; triethylamine; In dichloromethane; at 21℃;
General procedure: [0268] In a mixture of <strong>[66490-61-7]3,5,6-tribromopyrazin-2-amine</strong> (146 mg, 0.5 mmol), triethylamine (202 mg, 2 mmol), and catalytic amount of DMAP (5 mol %) in dry CH2CI2 (5 mL) was added 3- fluorobenzoylchloride (176 mg, 1 mmol) at room temperature. The mixture was stirred at room temperature overnight, and concentrated under reduced pressure. The residue was then dissolved in MeOH (5 mL) and K2CO3 (100 mg) was added. The mixture was stirred at 60 C for 1 h. The mixture was then reduced down and the product purified via silica chromatography (ethyl acetate:hexanes).
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