Reagents and conditions: (a) NIS, TMSOTf, CH2Cl2, −20 oC, 45 min, 85%; (b) NIS, TMSOTf, CH2Cl2, −30 oC, 25 min, 82%; (c) NaOCH3, CH3OH, room temperature, 1 h, 95%; (d) NIS, TMSOTf, 3, CH2Cl2, −15 °C, 40 min, 78%; (e) (i) NaOCH3, CH3OH, room temperature, 2 h (ii) 80% AcOH, 80 °C, 2 h; (iii) 20% Pd(OH)2-C, H2, CH3OH, room temperature, 16 h, 57% for three steps.