1: 88 percent / Na; EtOH; liq. NH3 / tetrahydrofuran / 1 h / Heating 2: 37 percent / CH2Cl2 / 40 h / 20 °C 3: 72 percent / DIBAL / tetrahydrofuran / 40 h / 20 °C 4: 90 percent / aq. HCl / methanol / 6 h / Heating View Scheme

trifluoroacetic acid in dimethyl sulfoxide T=70°C; 2 h;