1: 2.) polyphosphoric acid / 1.) 120 deg C, 2 h, 2.) 160 deg C, 1 h 2: 78.7 percent / 15 percent NaOH / 0.75 h / Heating 3: 53.8 percent / KBr, Pb(OAc)4 / H2O; acetic acid / 30 °C 4: toluene / 3 h / Heating 5: 89 percent / PCl3 / dimethylformamide / 2 h / Ambient temperature View Scheme

1: 2.) polyphosphoric acid / 1.) 120 deg C, 2 h, 2.) 160 deg C, 1 h 2: 78.7 percent / 15 percent NaOH / 0.75 h / Heating 3: 53.8 percent / KBr, Pb(OAc)4 / H2O; acetic acid / 30 °C 4: toluene / 3 h / Heating 5: 59 percent / PCl3 / dimethylformamide / 2 h / Ambient temperature View Scheme