55745-70-5

496-16-2

68-12-2

55745-70-5

2,3-Dihydrobenzofuran-5-carbaldehyde was synthesized as follows: in a dry reaction flask, 2,3-dihydrobenzofuran (100 g, 0.833 mol) was dissolved in N,N-dimethylformamide (355.0 ml). Under stirring, phosphorus oxychloride (255.58 g, 1.666 mol) was slowly added dropwise, and the reaction temperature was controlled to be maintained between 80°C and 85°C. The reaction mixture was stirred continuously at this temperature for 4 to 5 hours, during which the progress of the reaction was monitored by high performance liquid chromatography (HPLC). Upon completion of the reaction, the mixture was carefully poured into ice water to quench the reaction. Subsequently, the organic layer was separated by extraction with toluene (2000 ml). The organic layer was washed sequentially with 5% sodium bicarbonate solution (500 ml) and 10% brine solution (500 ml) to remove residual acid and DMF.The washed organic layer was subjected to distillation under reduced pressure at 50 °C to 60 °C to remove the solvent to give the crude product. By further purification, 2,3-dihydrobenzofuran-5-carbaldehyde was obtained in 85% to 90% yield and 90% to 92% purity.