1: 85 percent / Et3N / CH2Cl2 / 1.) 0 deg C, 2 h, 2.) r.t., 4 h 2: 77 percent / 1 N HCl / tetrahydrofuran / 12 h / 60 °C 3: 80 percent / Et3N / tetrahydrofuran / 3 h / -70 °C 4: 75 percent / pyridine / 12 h / 70 - 80 °C 5: 90 percent / NaN3 / dimethylformamide / 36 h / 100 °C 6: 98 percent / NaOMe / methanol / 2 h / Ambient temperature View Scheme

With  toluene-4-sulfonic acid in  methanol 24 h;  Ambient temperature;