General procedure for the synthesis of 2-methylamino-3-nitro-6-chloropyridine (9) from 2,6-dichloro-3-nitropyridine (8) (2.0 g, 10.4 mmol) and monomethylamine: 2,6-dichloro-3-nitropyridine (8) and sodium carbonate (2.75 g, 25.9 mmol) were suspended in ethanol (100 mL). Subsequently, methylamine solution (7.8 mL, 15.6 mmol, 2M) was added to the suspension and the resulting mixture was stirred and reacted for 3 hours at room temperature. Upon completion of the reaction, the yellow reaction solution was concentrated under reduced pressure and the residue was dissolved in ethyl acetate and washed sequentially with sodium bicarbonate solution and saturated brine. The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The resulting yellow solid was purified by recrystallization from ethanol to afford the target product 6-chloro-N-methyl-3-nitropyridin-2-amine (9) as a yellow solid (1.6 g, 82% yield). Mass spectrum (MS) m/z (M+H): calculated value=187.6; measured value=187.1. 1H NMR (400MHz, DMSO-d6): δ3.00 (3H, d, J=5.1Hz), 6.77 (1H, d, J=8.1Hz), 8.42 (1H, d, J=8.1Hz), 8.72 (1H, m).
