1: 85 percent / acetic anhydride, zinc chloride / acetic acid / 2 h / Heating 2: 90 percent / potassium dichromate / acetic acid / 15 h / Heating 3: dimethyl sulfoxide, sodium hydride 4: 80 percent 5: 95 percent View Scheme

1: 85 percent / acetic anhydride, zinc chloride / acetic acid / 2 h / Heating 2: 90 percent / potassium dichromate / acetic acid / 15 h / Heating 3: dimethyl sulfoxide, sodium hydride 4: 80 percent 5: 95 percent 6: 76 percent View Scheme

1: 85 percent / acetic anhydride, zinc chloride / acetic acid / 2 h / Heating 2: 90 percent / potassium dichromate / acetic acid / 15 h / Heating 3: dimethyl sulfoxide, sodium hydride 4: 80 percent 5: 95 percent 6: 76 percent 7: 81 percent View Scheme