1: 97 percent / hexamethyldisilazane / 12 h / Heating 2: 33 percent / mercury(II) bromide / 1,2-dichloro-ethane / 20 h / Ambient temperature 3: 47 percent / ammonia / methanol / 48 h / 20 °C View Scheme

1: 83 percent / bromine / dimethylformamide / 1.) room temperature, 2 d, 2.) reflux, 5 h 2: 92 percent / sodium / methanol / 0.25 h View Scheme

bromine in N,N-dimethyl-formamide 1.) room temperature, 2 d, 2.) reflux, 5 h;