Dowex 50W-X8 in methanol; water T=23°C; 36 h;

triphenylphosphine; diethylazodicarboxylate in tetrahydrofuran 2 h;

1: 98 percent / DMAP / pyridine; CH2Cl2 / 0.67 h / -20 °C 2: cesium acetate / dimethylformamide / Heating View Scheme

1: Dowex 50 W X-8 resin, H+ form / methanol / Ambient temperature 2: 80 percent / alkaline hydrolysis View Scheme

1: 100 percent / 4-(dimethylamino)pyridine / CH2Cl2 / 2 h / Ambient temperature 2: 94 percent / aq. HOAc / tetrahydrofuran / 6 h / 70 °C 3: 1.) dibutyltin oxide / 1.) benzene, reflux, 1 h, 2.) DMF, 30 min 4: 100 percent / 4-(dimethylamino)pyridine / CH2Cl2 / 1 h / 50 °C 5: 89 percent / 80percent aq. HOAc / 0.25 h 6: tetrazole / CH2Cl2 / 2 h / Ambient temperature 7: 0.304 g / m-CPBA / CH2Cl2 / 2 h / -40 °C 8: 80 percent / bromotrimethylsilane / CH2Cl2 / 1 h / 0 °C 9: 99 percent / 1 N NaOH / 3 h / 0 °C View Scheme