1.1: 87 percent / AcOH / H2O / 2 h / 40 °C 2.1: 70 percent / c-C5H5N / CH2Cl2 / 5 h / 20 °C 3.1: 100 percent / Amberlit IR-120 / methanol; tetrahydrofuran; H2O / 6.5 h / 60 °C 4.1: NaIO4 / ethanol; H2O / 24 h / 20 °C 4.2: HCl / acetone / 24 h / 20 °C 4.3: 82 percent / c-C5H5N / 4 h / 40 °C 5.1: 88 percent / tin(II) chloride / acetonitrile / 5 h / 65 °C 6.1: 91 percent / sodium methoxide / methanol / 1 h / 20 °C View Scheme