in dichloromethane T=0°C;

n-butyllithium; 1,1,1,3,3,3-hexamethyl-disilazane 1a.) THF, hexane, -78 deg C, 1b.) to 0 deg C, 30 min, 2a.) -78 deg C, 2b.) 0 deg C, 30 min; Yield given. Multistep reaction;