1: sodium tetrahydroborate / dimethyl sulfoxide / 3 h / 100 °C 2: 4-(N,N-dimethlyamino)pyridine; triethylamine / tetrahydrofuran / 3.5 h / 20 °C 3: methanol; caesium carbonate / 4 h / 20 °C 4: sodium periodate; ruthenium(III) chloride*(x)H2O / tetrachloromethane; water; acetonitrile / 8 h / 20 °C View Scheme