1: 78 percent / dioxane / 24 h / 80 °C / Dowex 50W-X8 (H+) 2: 1.) dibutyltin oxide, 2.) potassium carbonate / 1.) methanol, reflux, 1.5 h, 2.) DMF, RT, 12 h 3: 89.7 percent / pyridine / CH2Cl2 / 1.5 h / -20 °C 4: 50 percent / tetra-n-butylammonium fluoride (TBAF) / tetrahydrofuran / 3 h / -10 °C View Scheme

1: 75 percent / trimethylsilyl trifluoromethanesulfonate (TMSOTf), Et3SiH / CH2Cl2 / 18.5 h / Ambient temperature 2: 97 percent / DMAP, Et3N / CH2Cl2 / 2 h / Ambient temperature 3: 49.5 percent / K2CO3, 18-crown-6 / dimethylformamide / 20 h / 120 °C 4: 78 percent / BCl3 / hexane; CH2Cl2 / 1.) -78 deg C, 2.5 h; 2.) -18 deg C, 4 h View Scheme