zinc dibromide in dichloromethane 4 h; Ambient temperature;

1: 1) N,N,N',N'-tetramethylethylenediamine, t-BuLi / THF, pentane 1) -78 deg C, 40 min 2) -78 deg C, 3 h 2: 100 percent / CF3COOH / CH2Cl2 / 2 h / Ambient temperature View Scheme

1: 1) N,N,N',N'-tetramethylethylenediamine, t-BuLi / THF, pentane 1) -78 deg C, 40 min 2) -78 deg C, 3 h 2: 100 percent / CF3COOH / CH2Cl2 / 3 h / Ambient temperature View Scheme