3,5-DIBROMO-6-CHLOROPYRAZIN-2-AMINE synthesis

Yield:566205-01-4 94.7%

Reaction Conditions:

with N-Bromosuccinimide in water;acetonitrile at 0 - 20; for 18 h;

Steps:

1
Synthesis Example 1 2-Amino-3,5-dibromo-6-chloropyrazine (4) To a solution of 2-amino-6-chloropyrazine (3) (8.00 g, 61.8 mmol) in acetonitrile (80 mL) was gradually added N-bromosuccinimide (NBS) (27.5 g, 155 mmol) at 0° C. After elevating to room temperature, the mixture was stirred overnight (18 hours). To the mixture was added water and the product was extracted with diethyl ether (*3). The combined organic extract was washed successively with water (*1) and brine (*1), followed by drying over anhydrous sodium sulfate. After filtration and concentration under reduced pressure, the residue was purified by silica gel flash column chromatography (n-hexane/ethyl acetate=3/1) to give 2-amino-3,5-dibromo-6-chloropyrazine (4) (16.8 g, 58.5 mmol, 94.7%) as a yellow solid. TLC R_f=0.31 (n-hexane/ethyl acetate=4/1); ¹H NMR (500 MHz, CDCl₃) δ 5.14 (s, 2H); ¹³C NMR (126 MHz, CDCl₃) δ 120.7, 122.0, 146.1, 151.0.

References:

NATIONAL UNIVERSITY CORPORATION TOKYO MEDICAL AND DENTAL UNIVERSITY;JNC CORPORATION US2012/232272, 2012, A1 Location in patent:Page/Page column 18

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