1: 1.) BuLi, 2.) SO2, 3.) Cl2 / 1.) hexane, room temperature, 2 h, 2) -40 deg C to room temperature, overnight, 3.) H2O, 15 min 2: tetrahydrofuran / -10 - 20 °C 3: HCl / acetone / 72 h / Ambient temperature View Scheme

1: With n-butyllithium in hexane T=-60 - 20°C; 3.25 h; Inert atmosphere; 2: With sulfur dioxide in tetrahydrofuran; hexane T=-65 - 20°C; Inert atmosphere; 3: With NaOAc·3H2O; hydroxylamine-o-sulphonic acid in water T=0 - 20°C;