boron tribromide in dichloromethane 12 h;

1: potassium carbonate / dimethylformamide 2: acetic acide / Heating 3: 87 percent 4: trimethylbenzyl ammonium hydroxide 5: hydrogen / Raney nickel / ethanol 6: 72 percent 7: 96 percent / ethanol / 20 h / Heating 8: 84 percent / boron tribromide / CH2Cl2 / 12 h View Scheme

1: 87 percent 2: trimethylbenzyl ammonium hydroxide 3: hydrogen / Raney nickel / ethanol 4: 72 percent 5: 96 percent / ethanol / 20 h / Heating 6: 84 percent / boron tribromide / CH2Cl2 / 12 h View Scheme

1: acetic acide / Heating 2: 87 percent 3: trimethylbenzyl ammonium hydroxide 4: hydrogen / Raney nickel / ethanol 5: 72 percent 6: 96 percent / ethanol / 20 h / Heating 7: 84 percent / boron tribromide / CH2Cl2 / 12 h View Scheme

1: trimethylbenzyl ammonium hydroxide 2: hydrogen / Raney nickel / ethanol 3: 72 percent 4: 96 percent / ethanol / 20 h / Heating 5: 84 percent / boron tribromide / CH2Cl2 / 12 h View Scheme

1: 72 percent 2: 96 percent / ethanol / 20 h / Heating 3: 84 percent / boron tribromide / CH2Cl2 / 12 h View Scheme

1: 96 percent / ethanol / 20 h / Heating 2: 84 percent / boron tribromide / CH2Cl2 / 12 h View Scheme