potassium carbonate in toluene T=80 - 85°C; 13 h; Product distribution / selectivity;

1: pyridine / dichloromethane / 12 h / 5 - 20 °C / Inert atmosphere 2: 4-(N,N-dimethlyamino)pyridine / N,N-dimethyl-formamide / 15 - 30 °C / Inert atmosphere 3: 100 - 110 °C / Inert atmosphere 4: ethanol; sodium hydroxide / Inert atmosphere; Reflux View Scheme