1: 80 percent / polyphosphoric acid / 1.5 h / 150 °C 2: 88 percent / hydrazine monohydrate; KOH / bis-(2-hydroxy-ethyl) ether / 1.5 h / 200 °C View Scheme

1: 80 percent / polyphosphoric acid / 1.5 h / 150 °C 2: 88 percent / hydrazine monohydrate; KOH / bis-(2-hydroxy-ethyl) ether / 1.5 h / 200 °C 3: 80 percent / N,N-dimethyl-acetamide / 1 h / Heating View Scheme