反应详情

To a stirred solution of 110 (66.5 g, 265 mmol) in glacial acetic acid (400 mL), sulfuric acid (80 mL) was added to the solution. Bromine (28 mL, 530 mmol) dissolved in acetic acid (150 mL) was added dropwise into the mixture. The reaction mixture was allowed to stir until NMR spectroscopy indicated that all of the starting material 110 had been consumed. The solution was concentrated under reduced pressure and then neutralized by addition of 1N NaOH solution and then extracted with EtOAc. The crude product 111 was purified by recrystallization from CH2Cl2 to afford 5 (70.4 g, 81%). mp 210-212° C.; IR (KBr, cm−1) 2931, 1692, 1603, 1563, 1475, 1445, 1375, 1259, 1235, 1130, 1090; 1H NMR (CDCl3) δ 9.36 (s, 1 H), 7.63 (dd, J=2.22, 8.58 Hz, 1 H), 7.54-7.39 (m, 6 H), 7.12 (d, J=8.61 1 H), 3.76 (q, J=6.3 Hz, 1 H), 1.76 (d, J=6.45 Hz, 3 H). MS (EI) m/e (relative intensity) 330 (M++1, 21), 329 (M+, 50), 328 (22), 327 (48), 289 (44), 288 (46), 287 (100), 286 (49), 285 (60), 205 (25), 77 (49); [α]26D=313.1 (c 0.34, EtOAc).