potassium hydroxide; carbonic acid diethyl ester T=95 - 100°C; 5 h;

1: 94 percent / aq. NaOH / tetrahydrofuran / 2.5 h / 20 °C 2: 58 percent / dimethylformamide / 2 h / 80 °C 3: 54 percent / hydrazine hydrate / ethanol / 3 h / Heating View Scheme

1: 69 percent / Et3N / CH2Cl2 / 5 h / 20 °C 2: 72 percent / TfOH / chlorobenzene / 0.17 h / 80 °C View Scheme

triethylamine in dichloromethane T=20°C; 5 h;