1.1: tert-butyllithium / toluene; pentane / 1.25 h / -78 - 0 °C 1.2: 72 percent / toluene; pentane / 2 h / -78 - 20 °C 2.1: 86 percent / p-toluenesulfonic acid / tetrahydrofuran; H2O / 12 h / 55 °C 3.1: 88 percent / triphenylphosphine; diethyl azodicarboxylate / tetrahydrofuran / 1 h / 0 °C View Scheme

1: 85 percent / n-BuLi / diethyl ether / -78 - 20 °C 2: 83 percent / p-TsOH / tetrahydrofuran; H2O / 55 °C 3: 5 percent / PPh3; DEAD / tetrahydrofuran / 0 °C View Scheme