1: PBr3 / diethyl ether / 2 h / 1.) Et2O, 0 deg C; 2.) room temperature, 2 h 2: 2 h / 60 °C 3: 40 percent / KOH / tetrahydrofuran / 1 h / Ambient temperature 4: 1.) DIBAH; 2.) MnO2 / 1.) THF, 0 deg C, 15 min; 2.) Et2O, room temperature, 30 min 5: 43 percent / KOH / tetrahydrofuran / 1 h / 0 °C 6: 1.) DIBAH; 2.) MnO2 / 1.) THF, 0 deg C, 15 min; 2.) Et2O, room temperature, 30 min 7: 2 percent / NaOMe / methanol; dimethylformamide / 3 h / Ambient temperature View Scheme