1.1: n-butyllithium / tetrahydrofuran / 0.17 h / -78 °C 1.2: 97 percent / tetrahydrofuran / 0.17 h / -78 °C 2.1: LDA / tetrahydrofuran / 0.5 h / -78 °C 2.2: 80 percent / n-butyllithium / tetrahydrofuran / 2.5 h / -78 - 20 °C View Scheme