tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C; 3 h; Inert atmosphere;

1: NEt3 / CH2Cl2 / 1) 0 deg C, 30 min, 2) RT, 2h 2: 73 percent / LiBr / tetrahydrofuran / 2 h / Heating 3: 1) Mg / 1) Et2O, 2) Et2O, RT, overnight 4: 90 percent / Bu4NF / tetrahydrofuran / 0.17 h / Ambient temperature 5: p-TsOH / methanol / 10 h / Ambient temperature View Scheme