1.1: 74 percent / ammonium acetate; glacial acetic acid / toluene / Heating 2.1: sodium / ethanol / 0.5 h / 20 °C 2.2: 64 percent / ethyl chloroformate / tetrahydrofuran / 12 h / Heating 3.1: 76 percent / manganese(IV) oxide / toluene / 8 h / Heating 4.1: 29 percent / aq. hydrochloride acid / 14 h / Heating View Scheme