2: pyridine / CH2Cl2 / 0.5 h / 0 °C 3: 57 percent / p-toluenesulphonic acid / methanol / Ambient temperature 4: pyridine / CH2Cl2 5: 93 percent / K2CO3 / methanol / 0.17 h / 0 °C 6: p-toluenesulfonic acid / CH2Cl2 7: 85 percent / KOH / H2O; ethanol / 2 h / 45 °C 8: 85 percent / chromic acid 9: 68 percent / acetic acid / H2O View Scheme