water; sodium hydroxide in ethanol T=20°C; 48 h;

tri-n-butyl-tin hydride in toluene T=65°C; 2 h;

trifluoroacetic acid in dichloromethane T=20°C; 0.5 h;

1: 61 percent / N-bromosuccinimide; acetic acid; formic acid / 0.5 h / 20 °C 2: NaOH / ethanol / 24 h / Heating View Scheme

1.1: acetic anhydride / 1 h / 60 °C 1.2: 90 percent / CH2Cl2 / 1.5 h / 20 °C 2.1: t-BuOCl; triethylamine / tetrahydrofuran / 0.5 h / -78 °C 2.2: tetrahydrofuran / 1.5 h / -78 - 20 °C 2.3: H2O2; NaOH / tetrahydrofuran; H2O / 1 h / 20 °C 3.1: 61 percent / N-bromosuccinimide; acetic acid; formic acid / 0.5 h / 20 °C 4.1: NaOH / ethanol / 24 h / Heating View Scheme

1.1: 18 h / 20 °C 2.1: t-BuOCl; triethylamine / tetrahydrofuran / 0.5 h / -78 °C 2.2: tetrahydrofuran / 1.5 h / -78 - 20 °C 2.3: H2O2; NaOH / tetrahydrofuran; H2O / 1 h / 20 °C 3.1: 61 percent / N-bromosuccinimide; acetic acid; formic acid / 0.5 h / 20 °C 4.1: NaOH / ethanol / 24 h / Heating View Scheme

1.1: t-BuOCl; triethylamine / tetrahydrofuran / 0.5 h / -78 °C 1.2: tetrahydrofuran / 1.5 h / -78 - 20 °C 1.3: H2O2; NaOH / tetrahydrofuran; H2O / 1 h / 20 °C 2.1: 61 percent / N-bromosuccinimide; acetic acid; formic acid / 0.5 h / 20 °C 3.1: NaOH / ethanol / 24 h / Heating View Scheme

1.1: t-BuOCl; triethylamine / tetrahydrofuran / 0.5 h / -78 °C 1.2: tetrahydrofuran / 1.5 h / -78 - 20 °C 1.3: H2O2; NaOH / tetrahydrofuran; H2O / 1 h / 20 °C 2.1: 61 percent / N-bromosuccinimide; acetic acid; formic acid / 0.5 h / 20 °C 3.1: NaOH / ethanol / 24 h / Heating View Scheme

1: diethyl ether 2: triethylamine / N,N-dimethyl-formamide 3: tert-butylhypochlorite / tetrahydrofuran 4: trifluoroacetic acid / dichloromethane View Scheme

1: tert-butylhypochlorite / tetrahydrofuran 2: trifluoroacetic acid / dichloromethane View Scheme