1: 91 percent / Dowex 50W-8H / 1 h / Heating 2: 82 percent / pyridine / 2.5 h / 0 deg C to r.t. 3: 10 percent / TMSOTf / acetonitrile / 0.42 h / 0 °C 4: 49 percent / 1M NaOH / H2O / 1 h / Heating View Scheme

1: 91 percent / Dowex 50W-8H / 1 h / Heating 2: 82 percent / pyridine / 2.5 h / 0 deg C to r.t. 3: TMSOTf / acetonitrile / 0.17 h / 0 °C 4: 89 percent / NH3 / methanol / 16 h / 20 °C View Scheme

1.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 0.5 h / 0 °C 1.2: 35 h / 20 °C 2.1: acetic acid / water / 5 h 3.1: sodium tetrahydroborate / methanol / 0.15 h / 0 - 20 °C View Scheme

lithium aluminium tetrahydride in diethyl ether T=20°C; 16 h;