[Synthesis]
Ethyl 4-fluoro-3-nitrobenzoate (10.0 g, 46.9 mmol) prepared in Step 1-1-1 was dissolved in methanol (40 mL) and triethylamine (10 mL, 70.4 mmol) was added. A 40% methylamine-methanol solution (5.50 g, 70.4 mmol) was slowly added to the reaction mixture under ice bath cooling conditions. The reaction mixture was stirred continuously for 1 h under ice bath cooling and then ice water was added to quench the reaction. The precipitate was separated by filtration and washed with cold water. The washed product was subjected to cyclic drying overnight to afford ethyl 4-methylamino-3-nitrobenzoate (10.4 g, 99% yield) as a yellow powder.1H-NMR (CDCl3) δ: 8.87 (d, J = 1.9 Hz, 1H), 8.33 (brs, 1H), 8.08 (dd, J = 1.9, 9.2 Hz, 1H), 6.87- 6.84 (m, 1H), 4.35 (q, J = 6.9 Hz, 2H), 3.08 (d, J = 5.0 Hz, 3H), 1.38 (t, J = 6.9 Hz, 3H). Mass spectrum (m/z): 224 (M+), 179, 105 (base peak). |