1: 99 percent / n-Bu4NF / tetrahydrofuran / Ambient temperature 2: 91 percent / DMAP / CH2Cl2 / 18 h / 0 - 5 °C 3: 80 percent / NaBH4 / dimethylsulfoxide / 2 h / 85 °C 4: 93 percent / NaIO4, AcOH / H2O View Scheme