Multi-step reaction with 3 steps 1.1: 1H-imidazole / dichloromethane / 2 h / 20 °C2.1: trimethylaluminum / hexane; dichloromethane / 0.5 h / 20 °C2.2: 1 h / 20 °C3.1: methyllithium / tetrahydrofuran; hexane / 0.5 h / -78 °C3.2: 0.5 h / -78 °C