1: With N-bromosuccinmide; 2,2'-azo-bisisobutyronitrile in tetrachloromethane 7 h; Heating / reflux; 2: With sodium acetate in DMF (N,N-dimethyl-formamide) T=70°C; 17 h;

in N,N-dimethyl-formamide T=70°C; 17 h;