1: 34 percent / 2 h / 150 °C 2: 1.) O3, 2.) Me2S / 1.) CH2Cl2, MeOH, -78 deg C, 30 min, 2.) CH2Cl2, MeOH, 0 deg C, 2 h 3: 63 percent / NaBH4 / CH2Cl2; propan-2-ol / 0.5 h / -10 °C 4: 77 percent / 1N aq. NaOH / dimethylformamide / 4 h / Ambient temperature View Scheme

1: 34 percent / 2 h / 150 °C 2: 1.) O3, 2.) Me2S / 1.) CH2Cl2, MeOH, -78 deg C, 30 min, 2.) CH2Cl2, MeOH, 0 deg C, 2 h 3: 63 percent / NaBH4 / CH2Cl2; propan-2-ol / 0.5 h / -10 °C 4: 77 percent / 1N aq. NaOH / dimethylformamide / 4 h / Ambient temperature 5: 1.) 47percent aq. HBr, 2.) Ph3PBr2 / 1.) EtOH, reflux, 15 min, 2.) DMF, RT, 4 h View Scheme