1: With TMPZnCl*LiCl in tetrahydrofuran T=25°C; 0.5 h; Inert atmosphere; 2: With iodine in tetrahydrofuran 0.5 h; Inert atmosphere;

2,2,6,6-tetramethyl-piperidine; n-butyllithium; iodine 1.) THF, hexane, -70 deg C, 2 h, 2.) THF, -70 deg C, 2 h; Yield given. Multistep reaction. Yields of byproduct given;