1: 78 percent / 80percent aq. H2O2, trifluoroacetic anhydride / 1) 0 deg C, 1 h; 2) 20 deg C, 30 min 2: 68 percent / CrO3 / acetic acid / 0.67 h / 70 °C 3: 81 percent / SnCl2*2H2O, conc. aq. HCl / ethanol / 2 h / 100 °C 4: 1) nitrosylsulfuric acid; 2) SnCl2*2H2O, conc. aq. HCl / 1) acetic acid, 20 deg C, 3 h; 2) 10 deg C, 1 h View Scheme

1: 82 percent / SnCl2*2H2O, conc. aq. HCl / ethanol / 2 h / 100 °C 2: 1) nitrosylsulfuric acid; 2) SnCl2*2H2O, conc. aq. HCl / 1) acetic acid, 20 deg C, 3 h; 2) 10 deg C, 1 h 3: 2) BF3 etherate / 1) 70 deg C, 4 h; 2) acetic acid, reflux, 3 h View Scheme

1: 78 percent / 80percent aq. H2O2, trifluoroacetic anhydride / 1) 0 deg C, 1 h; 2) 20 deg C, 30 min 2: 68 percent / CrO3 / acetic acid / 0.67 h / 70 °C 3: 81 percent / SnCl2*2H2O, conc. aq. HCl / ethanol / 2 h / 100 °C 4: 1) nitrosylsulfuric acid; 2) SnCl2*2H2O, conc. aq. HCl / 1) acetic acid, 20 deg C, 3 h; 2) 10 deg C, 1 h 5: 2) BF3 etherate / 1) 70 deg C, 4 h; 2) acetic acid, reflux, 3 h View Scheme

1: 82 percent / SnCl2*2H2O, conc. aq. HCl / ethanol / 2 h / 100 °C 2: 1) nitrosylsulfuric acid; 2) SnCl2*2H2O, conc. aq. HCl / 1) acetic acid, 20 deg C, 3 h; 2) 10 deg C, 1 h 3: 2) BF3 etherate / 1) 70 deg C, 4 h; 2) acetic acid, reflux, 3 h 4: 93 percent / 6 h / 75 °C View Scheme