Step 1-1-3 Synthesis of ethyl 3-amino-4-methylaminobenzoate: Ethyl 4-methylamino-3-nitrobenzoate (6.80 g, 30.3 mmol) prepared in Step 1-1-2 was dissolved in methanol (200 mL), and 5% palladium carbon catalyst (1.10 g) was added to the solution. The reaction mixture was stirred overnight at room temperature under hydrogen atmosphere. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated to afford ethyl 3-amino-4-methylaminobenzoate (4.85 g, 82% yield) as a light brown powder. The product was characterized by 1H-NMR (CDCl3): δ 7.92 (dd, J = 1.9, 8.5 Hz, 1H), 7.40 (d, J = 1.9 Hz, 1H), 6.58 (d, J = 8.5 Hz, 1H), 4.31 (q, J = 7.3 Hz, 2H), 3.99 (brs, 1H), 3.22 (brs, 2H), and 2.19 (s, 3H), 1.36 (t, J = 7.3 Hz, 3H). Mass spectral analysis showed m/z: 194 (M+, base peak), 149.
