1.1: tetrahydrofuran / 4 h / 60 °C 1.2: 55 percent / NaOH; H2O2 / CH2Cl2; methanol; H2O / 2 h / 55 °C 2.1: pyridine / 12 h / 20 °C 3.1: 576 mg / p-toluenesulfonic acid / methanol / 12 h / 20 °C View Scheme