in diethyl ether; pentane T=-25°C; 2 h;

Multi-step reaction with 3 steps 1: 90 percent / tetrahydrofuran; hexane / 2 h2: 1) MeLi, 2) Me3SiCl / 1) ether, 2) ether, THF, 1 h3: 98 percent / 80 °C / 0.01 Torr