1: sodium cyanoborohydride / acetic acid / 1 h / 20 °C / |Inert atmosphere 2: 4-(N,N-dimethlyamino)pyridine / acetic acid; dichloromethane / 5 h / 20 °C / |Inert atmosphere 3: boron trichloride / dichloromethane / 22 h / 0 - 20 °C / |Inert atmosphere 4: sodium dithionite; lithium hydroxide hydrate / water; tetrahydrofuran / 9 h / 20 °C / |Inert atmosphere View Scheme