1: 87 percent / DIBALH / toluene / 2 h / -78 - -40 °C 2: 98 percent / aq. HCl / tetrahydrofuran / 0.08 h / 20 °C 3: 97 percent / NaBH4 / tetrahydrofuran; H2O / 1.5 h / cooling 4: 74 percent / K2CO3 / acetonitrile / 3 h / Heating View Scheme

1: diisobutylaluminium hydride / toluene / -78 °C / |Inert atmosphere 2: tetrahydrofuran / 0.67 h / -78 °C / |Inert atmosphere 3: tetrabutyl ammonium fluoride / 28 h / 55 °C / |Inert atmosphere 4: methanesulfonyl chloride; triethylamine / tetrahydrofuran / 0.33 h / 0 °C / |Inert atmosphere 5: toluene / 22 h / 20 - 50 °C / |Inert atmosphere View Scheme