1: 95 percent / NaOH / methanol; H2O 2: 65 percent / BnNEt3Br, NaOH / CH2Cl2; H2O / 0.17 h / 25 °C 3: 87 percent / NaIO4 / tetrahydrofuran; H2O 4: TMSOTf, 2,6-lutidine / CH2Cl2 / - 78 deg C, 30 min, RT, 1 h View Scheme