boron tribromide in dichloromethane 1.) -78 deg C, 1 h, 2.) room temperature, 2 h;

1: 50 percent / tetrahydrofuran; diethyl ether / 0.5 h / Heating 2: 84 percent / boron tribromide / CH2Cl2 / 1.) -78 deg C, 1 h, 2.) room temperature, 2 h View Scheme

1: 77 percent / activated manganese dioxide / CHCl3 / 30 h / Heating 2: 50 percent / tetrahydrofuran; diethyl ether / 0.5 h / Heating 3: 84 percent / boron tribromide / CH2Cl2 / 1.) -78 deg C, 1 h, 2.) room temperature, 2 h View Scheme

1: 50 percent / tetrahydrofuran; diethyl ether / 0.5 h / Heating 2: 84 percent / boron tribromide / CH2Cl2 / 1.) -78 deg C, 1 h, 2.) room temperature, 2 h View Scheme

1: 95 percent / lithium aluminium hydride / tetrahydrofuran / 4 h / Ambient temperature 2: 77 percent / activated manganese dioxide / CHCl3 / 30 h / Heating 3: 50 percent / tetrahydrofuran; diethyl ether / 0.5 h / Heating 4: 84 percent / boron tribromide / CH2Cl2 / 1.) -78 deg C, 1 h, 2.) room temperature, 2 h View Scheme