boron trifluoride diethyl etherate; trifluoroacetic anhydride in dichloromethane T=20°C; 5 h;

1: With N-bromosuccinmide; dibenzoyl peroxide in 1,2-dichloro-ethane 3 h; Heating / reflux; 2: With triethylamine in 1,2-dichloro-ethane 2 h; Heating / reflux;