ethylmagnesium bromide 1.) THF, r.t., 0.5 h, 2.) r.t.; Yield given. Multistep reaction;

1: 96 percent / LDA / tetrahydrofuran / 1.) -75 deg C to -60 deg C, 2.) -70 deg C, 1 h 2: 1.) oxalyl chloride / 1.) ether, ice-bath cooling, 0.75 h, 2.) CH2Cl2, r.t., 15 h 3: 68 percent / K2CO3, n-Bu4NBr / 44 h / Heating 4: 99 percent / 1 N NaOH / methanol / Ambient temperature View Scheme