1: 57 percent / p-toluenesulphonic acid / methanol / Ambient temperature 2: pyridine / CH2Cl2 3: 93 percent / K2CO3 / methanol / 0.17 h / 0 °C 4: p-toluenesulfonic acid / CH2Cl2 5: 85 percent / KOH / H2O; ethanol / 2 h / 45 °C 6: 85 percent / chromic acid 7: 68 percent / acetic acid / H2O View Scheme