1: 90 percent / 2,6-lutidine / CH2Cl2 / 0 - 25 °C 2: 92 percent / 10percent NaOH / tetrahydrofuran / 0.5 h / 20 °C 3: 75 percent / acetonitrile / Heating 4: 49 percent / TBAF / tetrahydrofuran / Heating View Scheme