1: 1.) sec-BuLi / 1.) THF, cyclohexane, -78 deg C, 0.5 h, 2.) -78 deg C, 30 min, RT 2: NBS, pyridine / diethyl ether / 2 h / 0 °C / Irradiation 3: 1 N HCl / tetrahydrofuran / 24 h / Ambient temperature 4: methanol; H2O / 30 h / 85 °C View Scheme