1: sodium tetrahydroborate; acetic acid / dichloromethane / 8.5 h / 0 °C / Inert atmosphere 2: methanesulfonyl chloride; triethylamine / dichloromethane / 1 h / 20 °C / Inert atmosphere 3: palladium 10 on activated carbon; hydrogen / tetrahydrofuran / 72 h / 20 °C 4: trifluoroacetic acid / dichloromethane / 0.33 h / 20 °C / Inert atmosphere View Scheme