4-(N,N-dimethlyamino)pyridine; triethylamine in dichloromethane T=25°C; 2 h;

n-butyllithium in tetrahydrofuran; hexane

1: 1. diisopropylamine, n-butyllithium / 1. THF, 2 h; 2. THF a.) -78 deg C, 4 h, b.) r.t. 2: 81 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0.42 h / Ambient temperature 3: 100 percent / tetrahydrofuran / 2 h / 0 °C 4: 92 percent / DMAP, triethylamine / CH2Cl2 / 2 h / 25 °C View Scheme

1: 1. hexamethyldisilazane, n-BuLi / 1. THF, hexane, reflux, 3 h; 2. reflux, 2 h 2: 1. diisopropylamine, n-butyllithium / 1. THF, 2 h; 2. THF a.) -78 deg C, 4 h, b.) r.t. 3: 81 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0.42 h / Ambient temperature 4: 100 percent / tetrahydrofuran / 2 h / 0 °C 5: 92 percent / DMAP, triethylamine / CH2Cl2 / 2 h / 25 °C View Scheme

1: 100 percent / tetrahydrofuran / 2 h / 0 °C 2: 92 percent / DMAP, triethylamine / CH2Cl2 / 2 h / 25 °C View Scheme

1: 81 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0.42 h / Ambient temperature 2: 100 percent / tetrahydrofuran / 2 h / 0 °C 3: 92 percent / DMAP, triethylamine / CH2Cl2 / 2 h / 25 °C View Scheme

1: 40 percent / NaH / tetrahydrofuran / 3 h / 35 °C 2: 88 percent / 0.5percent hydrochloric acid / ethanol / 48 h / 0 °C View Scheme