1: 97 percent / p-TsOH / benzene 2: 97 percent / NaNH2 / H2O / 5 h / -33 °C 3: 82 percent / n-BuLi / hexane; tetrahydrofuran / 2 h / -78 °C View Scheme

sodium amide in dimethyl sulfoxide T=0°C; 8 h;