1.1: 18-crown-6 ether; potassium hexamethylsilazane / tetrahydrofuran; toluene / 0.5 h / Cooling 1.2: 2 h / 20 °C / Cooling 2.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 24 h / 20 °C 3.1: di-isopropyl azodicarboxylate; triphenylphosphine / toluene / 1.5 h 4.1: water; 2,3-dicyano-5,6-dichloro-p-benzoquinone / dichloromethane / 1 h / 20 °C 5.1: Grubb's 2nd generation catalyst / dichloromethane / 6 h / 40 °C 6.1: hydrogenchloride; water / tetrahydrofuran / 20 h View Scheme