1: 375 mg / diethyl ether; pentane / -78 deg C, 5 h, then -> RT, 0.5 h 2: 2.) tetra-n-butylammonium fluoride / 1.) hexane, reflux, 2 h, 2.) THF, 1 h 3: 80 percent / MnO2 / light petroleum / 1 h / 4 °C 4: CDCl3 / 40 °C View Scheme

1: 375 mg / diethyl ether; pentane / -78 deg C, 5 h, then -> RT, 0.5 h 2: 2.) tetra-n-butylammonium fluoride / 1.) hexane, reflux, 2 h, 2.) THF, 1 h 3: 80 percent / MnO2 / light petroleum / 1 h / 4 °C View Scheme

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;

in diethyl ether; pentane -78 deg C, 5 h, then -> RT, 0.5 h;