Synthesis
General procedure for the synthesis of 3,5-dichloropyrazine-2-carbonitrile from 3,5-dichloropyrazine-2-carboxamide: To a solution of acetonitrile (100 mL) of 3,5-dichloropyrazine-2-carboxamide (5.0 g, 13.3 mmol) obtained in Preparation Example 13.1 was added phosphorous triclorethylene (6.76 mL, 72.3 mmol), and the reaction was stirred for 4 hr at 80 °C. Upon completion of the reaction, the reaction mixture was diluted with water and subsequently extracted with ethyl acetate and the organic layer was washed with saturated saline. The organic layer was dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by column chromatography (eluent: 20% n-hexane/ethyl acetate) to afford 3,5-dichloropyrazine-2-carbonitrile (2.94 g, 65% yield) as a solid.
References
[1] Organic Letters, 2013, vol. 15, # 9, p. 2156 - 2159
[2] Patent: WO2016/6975, 2016, A2. Location in patent: Paragraph 461-463
[3] Patent: KR2016/7347, 2016, A. Location in patent: Paragraph 0359; 0363; 0364; 0365
[4] Patent: WO2018/22992, 2018, A1. Location in patent: Paragraph 0725; 0726
[5] Patent: US2018/72743, 2018, A1. Location in patent: Paragraph 1330-1331
