1: phosphate buffer / diethyl ether; tetrahydrofuran / 2 h / Ambient temperature 2: DMAP, Et3N / acetonitrile / 2 h / Ambient temperature 3: Bu3SnH, AIBN / toluene / 3 h / 100 °C 4: 84 percent / AcOH, TBAF / tetrahydrofuran / 0.25 h / Ambient temperature 5: 39 percent / AcOH / methanol / 120 h / Heating View Scheme