1: 21 percent / NaN3 / dimethylsulfoxide / 72 h / Heating 2: 96 percent / p-TsOH*H2O / CH2Cl2; methanol / 14 h 3: 95 percent / H2S; pyridine / H2O / 48 h View Scheme

1: 57 percent / sodium azide / dimethylformamide / 3 h / 90 °C 2: 99.5 percent / triphenylphosphine / tetrahydrofuran; H2O / Ambient temperature 3: 95 percent / pyridine / Ambient temperature 4: 72 percent / hydrochloric acid / tetrahydrofuran / 1 h / Heating 5: 66 percent / imidazole / dimethylformamide / 13 h / 60 °C 6: 89 percent / pyridine / 0.5 h / Ambient temperature 7: 90 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0.5 h / Ambient temperature 8: 47 percent / 1,1,3,3-tetramethylurea, stannous triflate, 4A molecular sieves / CH2Cl2 / 16 h / Ambient temperature 9: 95 percent / sodium methoxide / methanol / 1 h / Ambient temperature View Scheme

1: 21 percent / NaN3 / dimethylsulfoxide / 72 h / Heating 2: 96 percent / p-TsOH*H2O / CH2Cl2; methanol / 14 h View Scheme

1: 21 percent / NaN3 / dimethylsulfoxide / 72 h / Heating 2: 96 percent / p-TsOH*H2O / CH2Cl2; methanol / 14 h 3: 95 percent / H2S; pyridine / H2O / 48 h 4: 76 percent / aq. NaOAc / tetrahydrofuran / 1 h View Scheme