N-chloro-succinimide; anhydrous lithium acetate in water; acetonitrile T=20°C; 144 h;

1: With tetrakis(triphenylphosphine) palladium(0); 1,1,1,2,2,2-hexabutyl-distannane in toluene 69 h; Heating; 2: With chlorine in tetrachloromethane; dichloromethane T=20°C; 0.916667 h;