1: 52 percent / aq. lithium azide / acetic acid; tetrahydrofuran / 72 h / Ambient temperature 2: 77 percent / diisobutylaluminum hydride (DIBAL-H) / CH2Cl2; hexane / 2 h / -78 °C 3: 87 percent / pyridine / 15 h / Ambient temperature 4: 68 percent / stannic chloride / acetonitrile / 18 h / Ambient temperature 5: 31 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0.5 h / Ambient temperature View Scheme

in methanol 48 h; Irradiation;

water; acetic acid in tetrahydrofuran T=24°C; 22 h;

1: LiN3 / tetrahydrofuran; acetic acid; H2O 2: 77 percent / DIBAL / CH2Cl2 / -78 °C 3: pyridine 4: 55 percent / trimethylsilyl triflate / 1,2-dichloro-ethane 5: n-tetrabutylammonium fluoride / tetrahydrofuran View Scheme

With  lithium azide in  tetrahydrofuran; acetic acid 72 h;  Ambient temperature;