10A: 4-(2-aminoethyl)benzoic acid (200 mg, 0.99 mmol) and di-tert-butyl dicarbonate (260 mg, 1.2 mmol) were dissolved in 1 mL of 1 M NaOH aqueous solution. The reaction mixture was stirred at room temperature for 4 hours. Upon completion of the reaction, ethyl acetate was added followed by 10% aqueous citric acid solution. A white solid precipitate was observed, which was separated by filtration. The filtrate was extracted three times with ethyl acetate. The combined organic layers were washed sequentially with water and brine, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The residue was purified by rapid chromatography on silica gel with the eluent CH2Cl2/MeOH (100:0 to 95:5). A white solid product (47 mg, 16% yield) was obtained.1H NMR (CDCl3, ppm): δ 1.33 (s, 9H), 2.74 (t, J = 7.44 Hz, 2H), 3.14 (q, J = 6.78 Hz, 2H), 6.84 (br t, J = 5.43 Hz, 1H), 7.28 (d, J = 8.28 Hz, 2H ), 7.83 (d, J = 8.25 Hz, 2H).
