boron tribromide in hexane; dichloromethane 1.) -70 deg C, 1 h, 2.) RT, 2 h;

1: 65 percent / PPA / 0.5 h / 100 °C 2: 40 percent / BBr3 / CH2Cl2; hexane / 1.) -70 deg C, 1 h, 2.) RT, 2 h View Scheme

1: 18.5 g / BH3 / tetrahydrofuran / 2 h / Heating 2: 32 percent / acetonitrile / 16 h / Heating 3: 65 percent / PPA / 0.5 h / 100 °C 4: 40 percent / BBr3 / CH2Cl2; hexane / 1.) -70 deg C, 1 h, 2.) RT, 2 h View Scheme