1: 41 percent / pyridinium dichromate / CH2Cl2 / 5 h / 0 °C 2: 77 percent / SnCl4 / CH2Cl2 / 0.5 h / -78 °C 3: 80 percent / Ph3P / CH2Cl2 / 4 h / 20 °C View Scheme

triethylamine Ambient temperature;

triphenylphosphine in dichloromethane 4 h; Ambient temperature;