boron tribromide 1.) CH2Cl2, -78 deg C, 1 h 2.) CH2Cl2, -78 deg C to RT, 1 h; Yield given. Multistep reaction;

Multi-step reaction with 2 steps 1: 1.) LDA / 1.) THF, -78 deg C, 1 h, 2.) THF, from -78 deg C to RT, 1 h2: 92 percent / pyridine / CH2Cl2 / 12 h / Ambient temperature