copper(l) iodide; n-butyllithium; tert.-butyl lithium 1) pentan, -78 deg C, 4.5 h; 2) hexane, -10 deg C, 15 min; 3) -10 deg C, 20 min; 4) -78 deg C, 1 h; 5) ether, 6 h, -78 deg C, room temperature (0.5 h); Multistep reaction;