1: sodium tetrahydroborate / water; tetrahydrofuran / 20 °C 2: calcium carbonate; methyl iodide / water; acetonitrile / 47 h / 20 °C 3: 5 palladium on charcoal; hydrogen / ethanol 4: tetrafluoroboric acid / acetonitrile / 18 h / 20 °C View Scheme