hydrogen bromide in acetic acid T=22°C; 1 h;

1: glacial AcOH / a) 50 deg C, 2 h, b) RT, 2 h 2: 30 percent HBr, AcOH / 1.5 h / Ambient temperature View Scheme

1: 1.) Triethylamine, ethyl carbonochloridate / 1.) CHCl3, - 5 deg C, 20 min, 2.) reflux, 30 min 2: KF*2H2O, 18-crown-6 / methanol / 0.08 h / Heating 3: HBr / acetic acid / Ambient temperature; overnight View Scheme