1.1: ethyl acetate / 4 h / -50 °C / Inert atmosphere 2.1: water / 1 h / -50 - 20 °C / Inert atmosphere 3.1: water / 0.5 h / 20 °C / Inert atmosphere 4.1: sodium hydrogencarbonate / water / Inert atmosphere 4.2: 20 °C / Inert atmosphere 5.1: formic acid; titanium tetrachloride / dichloromethane / 1.25 h / 0 - 20 °C / Inert atmosphere View Scheme

1: ethyl acetate / 4 h / -50 °C / Inert atmosphere 2: water / 1 h / -50 - 20 °C / Inert atmosphere 3: water / 0.5 h / 20 °C / Inert atmosphere View Scheme