1: 65 percent / lithium 2,2,6,6-tetramethylpiperidine / tetrahydrofuran / -75 °C 2: 96 percent / iPrMgCl / diethyl ether / 0 °C View Scheme

2,2,6,6-tetramethylpiperidinyl-lithium in tetrahydrofuran T=-75°C;