1: 98 percent / i-Pr2NH, POCl3 / tetrahydrofuran / 1 h / -30 °C 2: 93 percent / NaBH4 / tetrahydrofuran; ethanol / 3 h / 20 °C 3: 1) t-BuOK / 1) THF, -40 deg C, 10 min, 2a) -40 deg C, 15 min, 2b) to 0 deg C 4: 5 percent aq. HClO4 / dioxane / Heating View Scheme

1: 98 percent / i-Pr2NH, POCl3 / tetrahydrofuran / 1 h / -30 °C 2: 1) t-BuOK / 1) THF, -40 deg C, 10 min, 2a) -40 deg C, 15 min, 2b) to 0 deg C 3: 86 percent / 5 percent aq. HClO4 / dioxane / 12 h / Heating View Scheme