1: 1) butyl lithium, diisopropylamine / 1) ether, 1h, 2) 6h, reflux 2: 95 percent / triethylamine / CH2Cl2 / 0.5 h / 0 °C 3: 1) CuI2 / 1) ether, -10 deg C, 10min, 2) 0 deg C, 4h 3) r.t. 4: 90 percent / PTS / methanol / 4 h View Scheme

1: 1) butyl lithium, diisopropylamine / 1) ether, 1h, 2) 6h, reflux 2: 95 percent / triethylamine / CH2Cl2 / 0.5 h / 0 °C 3: 1) CuI2 / 1) ether, -10 deg C, 10min, 2) 0 deg C, 4h 3) r.t. 4: 90 percent / PTS / methanol / 4 h 5: pyridine / Ambient temperature View Scheme

n-butyllithium; diisopropylamine 1) ether, 1h, 2) 6h, reflux; Yield given. Multistep reaction;

1: 1) butyl lithium, diisopropylamine / 1) ether, 1h, 2) 6h, reflux 2: 60 percent / pyridinium chlorochromate / CH2Cl2 / 2 h / Ambient temperature 3: 50 percent / tetrahydrofuran / 1) r.t., 6h, 2) 45 deg C, 1h 4: 92 percent / PTS / methanol / 4 h View Scheme