1: 77 percent / 1 N HCl / tetrahydrofuran / 12 h / 60 °C 2: 80 percent / Et3N / tetrahydrofuran / 3 h / -70 °C 3: 75 percent / pyridine / 12 h / 70 - 80 °C 4: 90 percent / NaN3 / dimethylformamide / 36 h / 100 °C 5: 98 percent / NaOMe / methanol / 2 h / Ambient temperature View Scheme