1: 95 percent / HF*pyridine; pyridine / tetrahydrofuran / 12 h / 20 °C 2: 87 percent / aq. KOH / ethane-1,2-diol / 3 h / 120 °C 3: 64 percent / Et3N; 2-chloro-1-methylpyridinium iodide / acetonitrile / 5 h / Heating 4: aq. HCl / tetrahydrofuran / 48 h / 40 °C View Scheme