1: 93 percent / triethylamine / tetrahydrofuran / 3 h / 0 - 25 °C 2: 84 percent / dimethylsulfoxide / 12 h / 45 °C 3: 77 percent / 0.1 N aq. NaOH / tetrahydrofuran; methanol / 0.5 h / Ambient temperature 4: 91 percent / triethylamine / tetrahydrofuran / 2 h / 0 - 25 °C 5: 82 percent / NaN3 / dimethylformamide / 40 °C 6: 1.) triphenylphosphine, 2.) H2O / 1.)THF, RT, 3 h, 2.) THF, RT, 3h 7: 6 N aq. HCl / 18 h / Ambient temperature View Scheme