1: 88 percent / sodium sand / diethyl ether / Ambient temperature 2: 79 percent / imidazole / dimethylformamide 3: O3, triphenyl phospine / CH2Cl2 / -78 °C 4: 68 percent / NaClO2, NaH2PO4, H2O2 / H2O; acetonitrile / 0 - 10 °C 5: 60 percent / PTSA / CHCl3 View Scheme