1: aq. NH4Cl / dimethylformamide / 5 h / 100 °C 2: 1.) NaOMe / 1.) THF, 20 min, 2.) THF, reflux, 6 h 3: KOH / bis-(2-hydroxy-ethyl) ether / 12 h / 200 °C 4: POCl3 / 4 h / Ambient temperature 5: Et3N / diethyl ether / 3 h / Ambient temperature View Scheme

1: 1.) NaOMe / 1.) THF, 20 min, 2.) THF, reflux, 6 h 2: KOH / bis-(2-hydroxy-ethyl) ether / 12 h / 200 °C 3: POCl3 / 4 h / Ambient temperature 4: Et3N / diethyl ether / 3 h / Ambient temperature View Scheme

1: KOH / bis-(2-hydroxy-ethyl) ether / 12 h / 200 °C 2: POCl3 / 4 h / Ambient temperature 3: Et3N / diethyl ether / 3 h / Ambient temperature View Scheme

1: POCl3 / 4 h / Ambient temperature 2: Et3N / diethyl ether / 3 h / Ambient temperature View Scheme

triethylamine in diethyl ether 3 h; Ambient temperature;