1: With 2,2,6,6-tetramethyl-piperidine; n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1 h; 2: With iodine in tetrahydrofuran; hexane T=-78°C; 1.5 h;

2,2,6,6-tetramethyl-piperidine; hydrogenchloride; n-butyllithium; ethanol 1.) THF/hexane, -70 deg C, 10 min;

Yield given. Multistep reaction. Yields of byproduct given;