Multi-step reaction with 4 steps 1.1: 58.1 percent / potassium carbonate; potassium iodide / dimethylformamide / 24 h / 150 °C2.1: t-butyllithium / tetrahydrofuran / 1 h / -78 °C2.2: 68 percent / tetrahydrofuran / -78 - 20 °C3.1: 94 percent / hydrochloric acid / acetic acid / 22 h / 20 °C4.1: t-butyllithium / tetrahydrofuran / 2 h / -78 °C4.2: 75.2 percent / triisopropyl borate / tetrahydrofuran / -78 - 20 °C