1: triethylamine / N,N-dimethyl-formamide / 24 h / 70 °C / |Inert atmosphere 2: water; trifluoroacetic acid / dichloromethane / 4 h / 0 °C / |Inert atmosphere 3: tetrabutyl ammonium fluoride / tetrahydrofuran / |Inert atmosphere 4: water / 0.17 h / |UV-irradiation; |Inert atmosphere View Scheme

1: triethylamine / N,N-dimethyl-formamide / 24 h / 70 °C / |Inert atmosphere 2: water; trifluoroacetic acid / dichloromethane / 4 h / 0 °C / |Inert atmosphere 3: tetrabutyl ammonium fluoride / tetrahydrofuran / |Inert atmosphere 4: water / 0.17 h / |UV-irradiation; |Inert atmosphere View Scheme

1: 61 percent / NaOMe / 2 h 2: 78 percent / Et3N*3HF; pyridine / tetrahydrofuran / 16 h / 20 °C 3: 78 percent / pyridine / 4 h / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; cyclohexane / 12 h / -40 °C 1.2: 52.5 percent / tetrahydrofuran; cyclohexane / 12 h / -78 °C 2.1: 92 percent / HgCl2; CaCO3 / acetonitrile; H2O / 8 h / Heating 3.1: 74 percent / Et3N; HF / tetrahydrofuran / 10 h / 20 °C 4.1: 73 percent / Irradiation View Scheme