1: 72.8 percent / Et3N / CH2Cl2 / 5 h / 0 °C 2: 95 percent / aq. HF / acetonitrile / 1.25 h / Ambient temperature 3: 98.5 percent / pyridine / 4 h / Ambient temperature 4: 70.1 percent / tetrahydrofuran / 11 h / Heating 5: 80.7 percent / aq. KOH / methanol / 16 h / 70 °C 6: 74.2 percent / 1-hydroxybenzotriazole / pyridine View Scheme