1.1: 66 percent / n-butyllithium / tetrahydrofuran; toluene / 0.5 h / -50 °C 2.1: Mg / tetrahydrofuran / 0.5 h / 20 °C 2.2: 89 percent / CuBr*Me2S / tetrahydrofuran / 0.5 h / -10 °C 3.1: 96 percent / HF/pyridine / tetrahydrofuran / 20 °C View Scheme

Multistep reaction;