1: 87 percent / NBS; AgNO3 / various solvent(s) / 0.5 h / Ambient temperature 2: 29 percent / AgNO3 / various solvent(s) / 17 h / 60 °C 3: 86 percent / KHCO3 / methanol; H2O / 0.5 h / Ambient temperature 4: 86 percent / acetone / 1 h / 50 °C View Scheme

With  N-bromosuccinmide; silver nitrate in  various solvent(s)0.5 h;  Ambient temperature;