1: 78 percent / TBAF / tetrahydrofuran / 8 h / 25 °C 2: 1) Et3N, 2,4,6-trichlorobenzoyl chloride, 2) 4-DMAP / 1) THF, 0 deg C, 15 min, 2) toluene, 25 deg C, 0.5 h 3: 92 percent / CF3CO2H / CH2Cl2 / 1) -20 deg C -> 0 deg C, 2) 0 deg C, 1 h 4: 65 percent / Na2EDTA, 1,1,1-trifluoroacetone, Oxone, NaHCO3 / acetonitrile; H2O / 0 °C View Scheme

1: 100 percent / TBAF / tetrahydrofuran / 4 h / 20 °C 2: Et3N / tetrahydrofuran / 0.83 h / 20 °C 3: polystyrene-supported DMAP / toluene / 2 h / 80 °C 4: 2.2 mg / polymer-supported TsOH / CH2Cl2 / 1 h / 20 °C View Scheme