1: H2SO4 / diethyl ether; H2O / 0.5 h / 5 °C 2: 90 percent / sodium borohydride / methanol / 5 °C 3: 100 percent / trifluoroacetic acid; H2O / 15 h / 4 °C 4: 65 percent / H2 / Pd/C / methanol / 15 h / 25 °C / 750.06 Torr View Scheme