1: tetrahydrofuran; hexamethylphosphoric acid triamide / 2 h / -78 - 90 °C 2: 1.) n-butyllithium / 1.) THF, 0 deg C, 2.) HMPT, 0 to 80 deg C, 4 h View Scheme

n-butyllithium 1.) THF, 0 deg C, 2.) HMPT, 0 to 80 deg C, 4 h; Yield given. Multistep reaction;

hydrogen; Lindlar's catalyst in ethanol P=760 Torr; Yield given. Yields of byproduct given. Title compound not separated from byproducts;