To a stirred solution of benzoic acid 3-amino-4-benzyloxy-phenyl ester (5.91 g, 18.5 mmol) (which was obtained in Example 16) in ethyl acetate (100 mL) and pyridine (20 mL) at 0° C. was added dropwise phenyl sulfonyl chloride (3.26 g, 18.5 mmol) in 50 mL of ethyl acetate. After one hour at 0° C. the mixture was warmed to room temperature and stirred at room temperature over night. The reaction mixture was washed with water and the organic layer was dried (MgSO4) and concentrated. Recrystallization from CH2Cl2/hexanes gave the title compound as a white solid (4.65 g, 61%); 1H NMR (300 MHz, CDCl3) δ 4.93 (s, 2H), 6.90-7.80 (m, 15H), 8.12 (d, J=8.5 Hz, 2H), 9.81 (s, 1H); MS (ES) m/z: 458.9 (MH+, 100%); HRMS Calcd. for C26H22NO5S(MH+): 459.1141. Found: 459.1151.
