1: 67 percent / DDQ / toluene / 20 h / Heating 2: sodium borohydride / tetrahydrofuran / 2 h / Ambient temperature 3: 83 percent / paratoluenesulfonic acid / toluene / 1 h / Heating View Scheme

1: 67 percent / DDQ / toluene / 20 h / Heating 2: 93 percent / hydrazin monohydrate, KOH / 1,2-dimethoxy-ethane; ethane-1,2-diol / 0.5 h / Heating View Scheme

2,3-dicyano-5,6-dichloro-p-benzoquinone in toluene 20 h; Heating;