N,N,N',N,-tetramethylethylenediamine; sec.-butyllithium; magnesium bromide in tetrahydrofuran 1.) -100 deg C, 5 min; 2.) 20 min;

sec.-butyllithium; magnesium bromide 1.) THF, -100 deg C, 2.) THF, form -70 deg C to -60 deg C; Yield given. Multistep reaction;