1: 1.) n-BuLi / 1.) THF, Et2O, pentane, -78 deg C, 5 min, 2.) THF, Et2O, pentane, -78 deg, 5 min 2: 1.) t-BuLi / 1.) THF, Et2O, pentane, -78 deg C, 30 min, 2.) THF, Et2O, pentane, a) -15 deg C, 5 min, b) from -15 deg C to RT 3: silica-gel-aq. oxalic acid / CH2Cl2 / 0.25 h / Ambient temperature View Scheme

Yield given. Multistep reaction;

Yield given. Multistep reaction. Yields of byproduct given;