7570-45-8

86-28-2

68-12-2

7570-45-8

Phosphorus oxychloride (POCl3, 1.4 mL, 10.2 mmol) was slowly added dropwise to stirring N,N-dimethylformamide (DMF, 3.2 mL, 40.8 mmol) under ice bath conditions for a controlled period of 10 minutes. The resulting slightly reddish solution was continued to be stirred for 1 h at room temperature. Subsequently, 9-ethyl-9H-carbazole (1.0 g, 5.1 mmol) was added over 10 minutes and the reaction mixture was placed in a microwave reactor at 100 °C for 1 hour. Upon completion of the reaction, the reaction mixture was cooled to room temperature and then carefully poured into crushed ice to quench the reaction. After the mixture was warmed to room temperature, it was extracted with ethyl acetate (EtOAc). The organic phases were combined, washed sequentially with water and saturated saline, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography with different ratios of heptane/ethyl acetate (EtOAc) as eluent to afford N-ethylcarbazole-3-carbaldehyde as a white solid (1.054 g, 93% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3) and 13C NMR (101 MHz, CDCl3).