1.1: lithium diisopropyl amide / tetrahydrofuran; hexane / 0.75 h / -78 °C / Inert atmosphere 1.2: 0.5 h / -78 °C / Inert atmosphere 1.3: 0.5 h 2.1: pyridine; dihydrogen peroxide / dichloromethane / 0.5 h / 20 °C 2.2: 3 h / Reflux 3.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / dichloromethane / 0 - 20 °C 4.1: boron trifluoride diethyl etherate / 3 h / -20 °C / Inert atmosphere 5.1: trifluoroacetic acid / dichloromethane / 1 h / 20 °C 5.2: 4 °C View Scheme