tetrabutyl ammonium fluoride in tetrahydrofuran T=-10°C; 3 h;

1: 1.) dibutyltin oxide, 2.) potassium carbonate / 1.) methanol, reflux, 1.5 h, 2.) DMF, RT, 12 h 2: 89.7 percent / pyridine / CH2Cl2 / 1.5 h / -20 °C 3: 50 percent / tetra-n-butylammonium fluoride (TBAF) / tetrahydrofuran / 3 h / -10 °C View Scheme

1: 1.) dibutyltin oxide, 2.) potassium carbonate / 1.) methanol, reflux, 1.5 h, 2.) DMF, RT, 12 h 2: 89.7 percent / pyridine / CH2Cl2 / 1.5 h / -20 °C 3: 50 percent / tetra-n-butylammonium fluoride (TBAF) / tetrahydrofuran / 3 h / -10 °C View Scheme

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: 89.7 percent / pyridine / CH2Cl2 / 1.5 h / -20 °C 2: 50 percent / tetra-n-butylammonium fluoride (TBAF) / tetrahydrofuran / 3 h / -10 °C View Scheme