sodium ethanolate in tetrahydrofuran; ethanol 1.5 h; Ambient temperature;

triethylamine in tetrahydrofuran 3 h; Ambient temperature;

1: 1.) Br2 / 1.) dioxane, dichloroethane, 60-70 deg C, 2 h, reflux, 4 h; 2.) 60-70 deg C, 2 h, reflux, 4 h 2: 82 percent / triethylamine / tetrahydrofuran / 3 h / Ambient temperature View Scheme

pyridine Ambient temperature; Yield given;