Synthesis
General procedure for the synthesis of 2-chloro-N4-methylpyridine-3,4-diamine from 4-methylamino-3-nitropyridine: 0.61 g (4.0 mmol) of 4-methylamino-3-nitropyridine was dissolved in 3.5 mL of concentrated hydrochloric acid. The reaction mixture was heated to 90 °C. Subsequently, a suspension of 3.5 g (15 mmol) of stannous chloride in concentrated hydrochloric acid (4 mL) was slowly added. The reaction mixture was reacted under reflux conditions for 3 hours. Upon completion of the reaction, the suspension was cooled to room temperature, poured into 75 mL of water and extracted with dichloromethane (2 x 30 mL). The organic layers were combined, dried with magnesium sulfate and concentrated in vacuum to give 0.60 g (95% yield) of 2-chloro-N4-methylpyridine-3,4-diamine as a white solid with a melting point of 168-169 °C.
References
[1] Patent: WO2005/26164, 2005, A1. Location in patent: Page/Page column 42
[2] Journal of Medicinal Chemistry, 2005, vol. 48, # 22, p. 6887 - 6896
[3] Patent: EP1568699, 2005, A1. Location in patent: Page/Page column 82
