1.1: Br2 / 16 h / 25 °C 2.1: i-Pr2Zn / diethyl ether / 2 h / 25 °C 2.2: CuCN*2LiCl / tetrahydrofuran / 0.17 h / -30 °C 2.3: 56 percent / tetrahydrofuran / 20 °C View Scheme

1.1: Br2 / 16 h / 25 °C 2.1: i-Pr2Zn / diethyl ether / 2 h / 25 °C 2.2: CuCN*2LiCl / tetrahydrofuran / 0.17 h / -30 °C 2.3: 46 percent / tetrahydrofuran / 20 °C View Scheme

With  methanol in  methanol; dichloromethane  dropwise addn. of the dichlorophenylborane to MeOH in CH2Cl2 (under N2 or Ar) at -78°C and stirring for 1 h; evapn. (vac.) while warming and distn. (vac.);   

With  bromine in  dichloromethane  slow addn. of Br2 in CH2Cl2 to dichlorophenylborane in CH2Cl2 (under N2or Ar) at 0°C and stirring at room temp. for 12 h; evapn. and distn. (vac.);