1: 1.) BF3*OEt2 / 1.) THF, -78 deg C, 10 min, 2.) THF, 20 min 2: i-Pr2NEt / CH2Cl2 / 12 h / Ambient temperature 3: TBAF / tetrahydrofuran / 6 h / 40 °C 4: 2,6-lutidine / tetrahydrofuran / 0.33 h 5: 1.) Pd(PPh3)4, H2O, 2.) AgNO3/SiO2 / 1.) THF, 1.7 h, 2.) CH2Cl2, hexane, 2 h 6: 67 percent / PPTS / ethanol / 16 h / 40 °C View Scheme