1.1: 7.80 g / -40 - 20 °C 2.1: 49 percent / diethyl ether / 2 h / -40 °C 3.1: Na2CO3; 1-chloroethyl chloroformate / 1,2-dichloro-ethane / 3 h / Heating 3.2: 86 percent / MeOH / 20 °C View Scheme

1: 168 h / Ambient temperature 2: 2.) trifluoroacetic acid / 1.) Et2O, -40 deg C, 3 h, 2.) Et2O, -78 deg C, 1 h 3: 1.25 h / 120 °C 4: AcOH, Zn / 24 h / Ambient temperature View Scheme