1: CH2Cl2 / 0.5 h / -78 °C 2: 74 percent / 30 percent HBr/AcOH / CH2Cl2 / 24 h / Ambient temperature 3: 56 percent / triethylsilane, trifluoroacetic acid / CH2Cl2 / 1) RT, 6 h, 2) reflux, 6 h 4: 55 percent / NaI, chlorotrimethylsilane / acetonitrile / 12 h / Heating View Scheme