n-butyllithium; triphenylemethane in tetrahydrofuran T=-78°C; 0.75 h; Yield given;

1: 86 percent / 1.) n-BuLi; 2.) ClSiMe3, n-BuLi / tetrahydrofuran; hexane / 1.) -60 deg C, -> room temp., then -78 deg C, 30 min; 2.) -90 deg C -> room temp., then room temp., 3 h, then -90 deg C, 30 min 2: 88 percent / LiOMe, phenanthroline / tetrahydrofuran; toluene / 0 deg C -> room temp., 10 h, then room temp., 2 d 3: 90 percent / Me2S / diethyl ether / 6 h / -45 °C View Scheme

n-butyllithium 1.) hexane, THF, r.t., 15 min; 2.) 45 min, -78 deg C, THF; Yield given. Multistep reaction;