1.1: potassium tert-butylate / tetrahydrofuran / 5 h / 0 °C / Inert atmosphere 2.1: n-butyllithium / tetrahydrofuran; hexane / 2 h / 0 °C / Inert atmosphere 2.2: 0 - 20 °C / Inert atmosphere 3.1: hydrogenchloride; water / methanol / 10 h / 20 °C / Inert atmosphere 4.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0 - 20 °C / Inert atmosphere View Scheme