616224-38-5

251643-13-7

616224-38-5

General procedure for the synthesis of methyl 4-amino-3-(methylamino)benzoate from methyl 3-(methylamino)-4-nitrobenzoate: at 0 °C, an aqueous sodium bisulfite solution (17.4 g, 100 mmol, dissolved in 80 mL of water) was slowly added to methyl-3-(methylamino)-4-nitrobenzoate (855 mg, 4.75 mmol) containing a tetrahydrofuran (70 mL) and ethanol (30 mL) in a mixed solution. The reaction solution was transformed from an orange solution to an orange suspension. The reaction mixture was stirred at room temperature for 2 hours, during which time the color of the suspension gradually changed from orange to yellow. Subsequently, saturated sodium bicarbonate solution (100 mL) was added, at which point the suspension further changed to colorless. The reaction mixture was extracted with ethyl acetate (2 x 100 mL). The organic phases were combined, washed with brine (30 mL) and dried over anhydrous magnesium sulfate. After filtration, the organic phase was concentrated and dried under high vacuum to afford methyl 4-amino-3-(methylamino)benzoate (586 mg, 68% yield) as a yellow oily product. After standing for 10 min, the oily material started to crystallize. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 2.89 (s, 3H), 3.37-3.81 (m, 2H), 3.85 (s, 3H), 6.67 (d, J = 8.01 Hz, 1H), 7.33 (d, J = 1.37 Hz, 1H), 7.44 (dd, J = 8.11,1.66 Hz, 1H).