potassium tert-butylate in dimethyl sulfoxide; benzene T=60 - 70°C; 0.166667 h;

Multi-step reaction with 2 steps 1: 1.) Mg; 2.) p-TsOH / 1.) Li2CuCl4 / 1.) 2 h, ether, room t.; 2.) methanol, water, 1 h, reflux2: 89 percent / 48percent HBr / 3 h / Heating