1: 85.5 percent / pyridinium p-toluenesulfonate / acetone; H2O / 2 h / Heating 2: 1) butyllithium / 1) THF-hexan, -78 deg C, 1.5 h, 2) -78 deg C, 1 h, room temperature, 15 h View Scheme

1: 85.5 percent / pyridinium p-toluenesulfonate / acetone; H2O / 2 h / Heating 2: 1) butyllithium / 1) THF-hexan, -78 deg C, 1.5 h, 2) -78 deg C, 1 h, room temperature, 15 h 3: 66 percent / N-bromosuccinimide / tetrahydrofuran; H2O / 1) 0 deg C, 1.5h, 2) 20 deg C, 1 h View Scheme