1.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 2 h / 0 °C 2.1: Dess-Martin periodane / dichloromethane / 2 h / 20 °C 3.1: potassium hexamethylsilazane / tetrahydrofuran; toluene / 0.5 h / -20 °C 3.2: 3 h / -20 °C 4.1: Grubb's 2nd generation catalyst / dichloromethane / 18 h / 20 - 40 °C 5.1: boron trifluoride diethyl etherate / 1 h / -8 °C 6.1: trifluoroacetic acid / dichloromethane / 19 h / 0 - 20 °C 7.1: triethylamine / dichloromethane / 0.17 h / 0 °C 8.1: sodium azide / water; N,N-dimethyl-formamide / 18 h / 90 °C 9.1: hydrogen / ethanol / 18 h / 20 °C 10.1: phosphoric acid / ethanol / 0.5 h / 55 °C View Scheme