a. In a 100 mL autoclave, 3-chloro-2,5-dimethylpyrazine (25.0 g, 176 mmol), 25-28% w/w ammonia solution (80 mL), and copper powder (1.69 g, 26.4 mmol) were added sequentially. After sealing the autoclave, the mixture was heated to 150 °C and reacted under vigorous stirring for 48 hours. After completion of the reaction, the mixture was cooled to room temperature and concentrated under reduced pressure. The residue was diluted with brine (100 mL) and subsequently extracted with ethyl acetate (4 x 100 mL). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was washed with petroleum ether to give 2-amino-3,6-dimethylpyrazine (17.6 g, 81% yield) as a light yellow solid. eSI MS: m/z 124 [M + H]+.
