1: 97 percent / Et3N / CH2Cl2 / 2 h / 0 °C 2: 94 percent / NaBH4, tert-butyl alcohol / CH2Cl2 / 70 h / Heating 3: 1.) borane, 2-methyl-2-butene, 2.) 30percent aq. H2O2 / 1.) THF, 0 deg C, 1 h, 2.) THF, H2O, 0 deg C, 30 min 4: Et3N / CH2Cl2 / 24 h / 0 °C 5: Et3N / tetrahydrofuran / 48 h / 80 °C View Scheme