1: 1.) t-BuOK / 1.) THF, RT, 40 min, 2.) from -60 deg C to RT, 6 h 2: 1.) n-BuLi / 1.) hexane, THF, -78 deg C, 15 min, 2.) from -78 deg C to RT 3: oxalyl chloride, DMF / benzene / 1 h / Ambient temperature View Scheme

1: CH2Cl2 / 5 h / 0 - 20 °C 2: thionyl chloride / CH2Cl2 / 2 h / 0 °C 3: 1.) n-BuLi, 2.) MgBr / 1.) hexane, THF, -78 deg C, 5 min, 2.) ether, benzene, from -78 deg C to RT, 1.5 h 4: 86 percent / aq. HCl / tetrahydrofuran / 2 h / Heating View Scheme