1.1: dipyridinium dichromate; N,N-dimethyl-formamide / 16 h / 20 °C / Inert atmosphere 2.1: sodium / 2.16 h / 0 - 20 °C / Inert atmosphere 3.1: Jone's reagent / water; acetone / 4.08 h / 0 °C / Inert atmosphere 4.1: lithium hydroxide hydrate / propan-1-ol; water / 12 h / 120 °C / Inert atmosphere 4.2: Dowex-50WX8 (H+ form) / Inert atmosphere View Scheme