Synthesis
General procedure for the synthesis of 2-amino-3-methyl-5-bromopyridine from 2-amino-3-methylpyridine: Bromine (15.4 mL, 0.30 mol) was slowly added dropwise to an anhydrous dichloromethane (1000 mL) solution of 2-amino-3-methylpyridine (32.44 g, 0.30 mol) under stirring at 0-2 °C for 1 hour. The cooling bath was then removed and the yellow suspension was allowed to continue stirring at room temperature for 3 hours and 40 minutes. Upon completion of the reaction, the mixture was alkalized to pH 9 with 2N sodium hydroxide solution (145 mL) and subsequently treated with a mixture of saturated aqueous sodium bicarbonate (100 mL) and saturated aqueous sodium thiosulfate (10 mL). The organic layer was separated, washed with brine, dried over magnesium sulfate and concentrated to give the brown solid product 2-amino-3-methyl-5-bromopyridine (56.83 g, 102% yield), which could be used in the next reaction without further purification.
References
[1] Patent: WO2004/13139, 2004, A2. Location in patent: Page 25-26
[2] Tetrahedron Letters, 2009, vol. 50, # 9, p. 1007 - 1009
[3] Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2001, vol. 40, # 11, p. 1129 - 1131
[4] Patent: CN105348177, 2016, A. Location in patent: Paragraph 0012; 0016
[5] Journal of Medicinal Chemistry, 2012, vol. 55, # 4, p. 1682 - 1697
