3-keto-2H,3H-1,2-benzisothiazole 1,1-dioxide in dichloromethane T=40°C; 24 h;

1.1: Mg / tetrahydrofuran / 2 h / 0 - 20 °C 1.2: 80 percent / tetrahydrofuran / 12 h / Heating 2.1: 0.14 g / NBS; benzoyl peroxide / CCl4 / 24 h / Heating 3.1: 3.75 g / AgOAc; H2O / ethanol; acetone / 24 h 4.1: 96 percent / DIBALH / CH2Cl2; toluene / 1.17 h / -78 - 0 °C 5.1: 87 percent / saccharin / CH2Cl2 / 24 h / 40 °C View Scheme

1: 96 percent / DIBALH / CH2Cl2; toluene / 1.17 h / -78 - 0 °C 2: 87 percent / saccharin / CH2Cl2 / 24 h / 40 °C View Scheme

1: 0.14 g / NBS; benzoyl peroxide / CCl4 / 24 h / Heating 2: 3.75 g / AgOAc; H2O / ethanol; acetone / 24 h 3: 96 percent / DIBALH / CH2Cl2; toluene / 1.17 h / -78 - 0 °C 4: 87 percent / saccharin / CH2Cl2 / 24 h / 40 °C View Scheme

1.1: Mg / tetrahydrofuran / 2 h / 0 - 20 °C 1.2: 80 percent / tetrahydrofuran / 12 h / Heating 2.1: 0.14 g / NBS; benzoyl peroxide / CCl4 / 24 h / Heating 3.1: 3.75 g / AgOAc; H2O / ethanol; acetone / 24 h 4.1: 96 percent / DIBALH / CH2Cl2; toluene / 1.17 h / -78 - 0 °C 5.1: 87 percent / saccharin / CH2Cl2 / 24 h / 40 °C View Scheme

1: 3.75 g / AgOAc; H2O / ethanol; acetone / 24 h 2: 96 percent / DIBALH / CH2Cl2; toluene / 1.17 h / -78 - 0 °C 3: 87 percent / saccharin / CH2Cl2 / 24 h / 40 °C View Scheme