b) Synthesis of methyl 4-(4-aminophenyl)butyrate
Methyl 4-(4-nitrophenyl)butyrate (3.05 g, 13.67 mmol) and Pd/C catalyst (1.0 g, 10% Pd, activated carbon carrier, 1.09 mmol) were suspended in methanol (40 mL). The reaction mixture was stirred under hydrogen atmosphere (balloon pressure) for 1 hour. After completion of the reaction, the reaction mixture was filtered through a diatomaceous earth pad (washed with ethyl acetate). The filtrate was concentrated under reduced pressure to give 2.33 g of methyl 4-(4-aminophenyl)butyrate (brown solid, yield: 88%). The product did not require further purification and could be used directly in the next step of the reaction.
1H NMR (CDCl3, 250MHz) δppm: 6.96 (d, J=8.5Hz, 2H), 6.63 (d, J=8.2Hz, 2H), 3.66 (s, 3H), 2.55 (t, J=7.6Hz, 2H), 2.31 (t, J=7.7Hz, 2H), 1.90 (q, J=7.6Hz, 2H).
