79456-34-1

Step 3) Synthesis of 5-bromo-3-trifluoromethylpyridin-2-ylamine (CAS No. [79456-34-1]): 3-trifluoromethylpyridin-2-ylamine (16.21 g, 100 mmol) was dissolved in acetonitrile (300 mL) at 5 °C and N-bromosuccinimide (NBS, 17.8 g, 100 mmol) was added slowly. The reaction mixture was warmed up to 23 °C with continuous stirring for 1 hour. Upon completion of the reaction, the mixture was quenched by pouring it into ice. The reaction mixture was extracted with ethyl acetate (EtOAc) and the organic phase was washed sequentially with saturated sodium bicarbonate (NaHCO3) solution and brine and dried over anhydrous sodium sulfate (Na2SO4). The solvent was removed by concentration under reduced pressure to give a yellow solid crude product. The crude product was purified by silica gel column chromatography using dichloromethane as eluent to give 2-amino-3-trifluoromethyl-5-bromopyridine as yellow solid (23.71 g, 98% yield). Mass spectrometry (EI) showed molecular ion peaks of 240.1 [M]+ and 242.0 [M+2]+.

[1] Patent: US2007/72879, 2007, A1. Location in patent: Page/Page column 18
[2] Patent: WO2010/8847, 2010, A2. Location in patent: Page/Page column 147
[3] Patent: CN105732602, 2016, A. Location in patent: Paragraph 0364; 0366; 0367; 0368; 0369
[4] Patent: WO2009/23179, 2009, A2. Location in patent: Page/Page column 196-197
[5] Patent: WO2015/158427, 2015, A1. Location in patent: Page/Page column 87; 88