1.1: NaBH4; NiCl2 / methanol / 0 °C 2.1: DIBAL-H / tetrahydrofuran 3.1: DIAD; PPh3 / tetrahydrofuran 4.1: Oxone; H2O / methanol / 60 °C 5.1: potassium hexamethyldisilylazide / 1,2-dimethoxy-ethane / 1 h / -78 °C 5.2: 1,2-dimethoxy-ethane / -78 - 20 °C 6.1: CAN; H2O / acetone 7.1: aq. NaOH / tetrahydrofuran; methanol 8.1: 61 percent / MsCl; Et3N; 2,4,6-trichlorobenzoyl chloride / 4-DMAP / toluene / Heating 9.1: 77 percent / TBAF / tetrahydrofuran / 20 °C View Scheme