Stage 2: Synthesis of methyl 4-amino-2-ethylbenzoate
15.0 g (72.3 mmol) of methyl 4-nitro-2-vinylbenzoate was dissolved in 150 mL of methanol and placed in an autoclave and subjected to a hydrogenation reaction for 15 h at 5 bar hydrogen pressure. Upon completion of the reaction, the reaction solution was filtered through diatomaceous earth to remove the catalyst. Subsequently, the solvent was removed by distillation under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography using cyclohexane/ethyl acetate (3:1, v/v) as eluent. Finally, 2.4 g (24% yield) of the target compound methyl 4-amino-2-ethylbenzoate was obtained. The product was analyzed by HPLC/MS showing: logP = 1.84; mass spectrum (m/z): 180.2 ([M+H]+). 1H NMR (CD3CN) data were as follows: δ 1.14 (t, 3H), 2.88 (q, 2H), 3.75 (s, 3H), 4.60 (br.s, 2H), 6.45-6.50 (m, 2H). 7.68 (d, 1H).
