1: 50 percent / hexamethylphosphoric triamide; tert-butylmagnesium chloride / tetrahydrofuran / 4 h 2: tetrabutylammonium fluoride / tetrahydrofuran / 1.5 h / 20 °C 3: acetic acid / dioxane; H2O / 0.25 h / 20 °C / UV-irradiation View Scheme

1: 85 percent / pyridine / 5 h / 0 - 20 °C 2: 85 percent / aq. NaOH / tetrahydrofuran; H2O / 6 h / Ambient temperature 3: 90 percent / tetrabutylammonium fluoride / tetrahydrofuran 4: 60 percent / sodium methoxide / methanol / 18 h / Heating View Scheme