N,N,N',N,-tetramethylethylenediamine; sec.-butyllithium in tetrahydrofuran 5 h; 1.) -78 deg C, 30 h, 2.) from -78 deg C to RT, 3 h;

1: CH2Cl2 / 1 h / Ambient temperature 2: NaH / tetrahydrofuran / 10 h / Ambient temperature 3: 91 percent / s-BuLi, TMEDA / tetrahydrofuran / 5 h / 1.) -78 deg C, 30 h, 2.) from -78 deg C to RT, 3 h View Scheme

1: NaH / tetrahydrofuran / 10 h / Ambient temperature 2: 91 percent / s-BuLi, TMEDA / tetrahydrofuran / 5 h / 1.) -78 deg C, 30 h, 2.) from -78 deg C to RT, 3 h View Scheme