1: triethylamine / tetrahydrofuran / Ambient temperature 2: 1.) n-butyllithium / 1.) THF, hexane, 0 deg C, 20 min, 2.) THF, hexane, -78 deg C, 15 min View Scheme

n-butyllithium 1.) THF, hexane, 0 deg C, 20 min, 2.) THF, hexane, -78 deg C, 15 min; Yield given. Multistep reaction;