Reagents and conditions: (a) CCl4:pyridine (4:1), I2 (3 equiv.), DMAP (0.2 equiv.), 110 °C, 4 h, 88%; (b) 65% HNO3, CHCl3, r.t. 5 min, 84%; (c) HCHO (3.0 equiv.), KOH (3.0 equiv.), CaCl2 (3.0 equiv.), MeOH (2 ml), NH4OH (10.0 equiv.), r.t. 4 h, 90%; (d) HCHO (3.0 equiv.), KOH (3.0 equiv.), CaCl2 (3.0 equiv.), MeOH (2 ml), r.t. 4 h, 92%.