1: 94.3 percent / 4 h / 100 °C 2: 85.4 percent / DBU / acetonitrile / 0.5 h / Heating 3: 95.6 percent / amberlite IRA-400 chloride ion-exchange resin / 2 h / Ambient temperature View Scheme

potassium hydroxide in acetone 3 h; Ambient temperature;

1: 68.7 percent / concd. sulfuric acid / dimethylformamide / a) 120 deg C, 2 h, b) 140 deg C, 2 h 2: 53.8 percent / potassium hydroxide / acetone / 3 h / Ambient temperature View Scheme