1.1: DIAD; PPh3 / tetrahydrofuran 2.1: Oxone; H2O / methanol / 60 °C 3.1: potassium hexamethyldisilylazide / 1,2-dimethoxy-ethane / 1 h / -78 °C 3.2: 1,2-dimethoxy-ethane / -78 - 20 °C 4.1: CAN; H2O / acetone 5.1: aq. NaOH / tetrahydrofuran; methanol 6.1: 61 percent / MsCl; Et3N; 2,4,6-trichlorobenzoyl chloride / 4-DMAP / toluene / Heating 7.1: 77 percent / TBAF / tetrahydrofuran / 20 °C View Scheme