1: 66 percent / TFA / CH2Cl2 / 1.) 0 deg C, 2.5 h, 2.) room temperature, 2.5 h 2: 99 percent / oxalyl chloride, DMF / CH2Cl2 / 2 h / Ambient temperature 3: 1.) n-BuLi / 1.) THF, -78 deg C, 20 min, 2.) THF, -78 deg C, 2.5 h; -78 deg C to room temperature View Scheme

trifluoroacetic acid in dichloromethane 1.) 0 deg C, 2.5 h, 2.) room temperature, 2.5 h;