1: With sodium methylate in methanol T=20°C; 24 h; 2: With barium dihydroxide in methanol T=20°C; 24 h; Further stages.;

1.1: 76 percent / hydrobromic acid / CH2Cl2; acetic acid / 3 h / 20 °C 2.1: 55 percent / silver trifluoromethanesulfonate; tetramethylurea / CH2Cl2 / 12 h / -20 °C 3.1: sodium methoxide / methanol / 24 h / 20 °C 3.2: 40 percent / Ba(OH)2 / methanol / 24 h / 20 °C View Scheme

1.1: 55 percent / silver trifluoromethanesulfonate; tetramethylurea / CH2Cl2 / 12 h / -20 °C 2.1: sodium methoxide / methanol / 24 h / 20 °C 2.2: 40 percent / Ba(OH)2 / methanol / 24 h / 20 °C View Scheme