1: 80 percent / LiBr / acetone / 3 h / 40 °C 2: 1.) Mg, 2) CuBr, 3.) aq. HCl / 2) THF, 10 deg C, 0.5 h, 20 deg C, 12 h; 3) THF, 20 deg C, 5 h View Scheme

With  lithium bromide in  acetone T=40°C; 3 h;