1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0.33 h / 20 °C / Inert atmosphere 2: tetra-(n-butyl)ammonium iodide / pyridine / 0.5 h / 0 °C / Inert atmosphere 3: trifluoroacetic acid / dichloromethane / 0.13 h / 0 °C / Inert atmosphere 4: dichloromethane / 0.25 h / 20 °C / Inert atmosphere 5: dichloromethane / 19 h / 20 °C / Inert atmosphere 6: sodium methylate / methanol / 1.5 h / Reflux; Inert atmosphere View Scheme