1: 91 percent / n-BuLi / tetrahydrofuran / -78 °C 2: 72 percent / NaH / 18-crown-6 / Ambient temperature 3: 88 percent / H2O ,CF3COOH / tetrahydrofuran / Ambient temperature 4: 81 percent / NaOH / ethanol View Scheme

1: 91 percent / n-BuLi / tetrahydrofuran / -78 °C 2: 72 percent / NaH / 18-crown-6 / Ambient temperature 3: 88 percent / H2O ,CF3COOH / tetrahydrofuran / Ambient temperature View Scheme