triethylamine in tetrahydrofuran 3 h; Ambient temperature;

1: 1.) Br2 / 1.) dioxane, dichloroethane, 2 h: 60-70 deg C, 4 h: reflux; 2.) 2 h: 60-70 deg C, 4 h: reflux 2: 55 percent / triethylamine / tetrahydrofuran / 3 h / Ambient temperature View Scheme

pyridine Ambient temperature; Yield given;