反应详情

温度

5 °C

A mixture of 3-amino-6-methyl-pyrazine-2-carboxylic acid ethyl ester (Example C) (2.0 g, 11 mmol), 4 mL water and 3.7 mL (33.1 mmol) hydrobromic acid 48% was cooled to 5° C. 2.5M NaNO2— solution in water (5.3 mL, 13.2 mmol) was added drop wise at 5° C. (N2-evolution!). The reaction mixture was stirred for 1 hr and poured then into ice-water. The reaction mixture was neutralized with Na2CO3 and extracted two times with ethyl acetate (200 mL each). The combined organic extracts were dried with sodium sulfate, filtered and evaporated. The crude product was purified by flash chromatography on silica gel (heptane/ethyl acetate 90:10->50:50 gradient). The desired compound was obtained as a colorless liquid (0.53 g, 20%), MS: m/e 245.1 (M+H+).

1. additionpoured
2. extractionextracted two times with ethyl acetate (200 mL each)
3. dry with materialThe combined organic extracts were dried with sodium sulfate
4. filtrationfiltered
5. customevaporated
6. customThe crude product was purified by flash chromatography on silica gel (heptane/ethyl acetate 90:10->50:50 gradient)