Example 101 Synthesis of 4-formyl-N,N-dimethylbenzamide: To an anhydrous dichloromethane (8 mL) suspension of 4-formylbenzoic acid (4.00 g, 26.7 mmol), thionyl chloride (2.92 g, 40.0 mmol) and N,N-dimethylformamide (0.6 mL) were added sequentially. The reaction was carried out dropwise at room temperature under nitrogen protection. Subsequently, the reaction mixture was heated to reflux for 2 hours. Upon completion of the reaction, it was cooled to room temperature and then slowly added dropwise to 33% aqueous dimethylamine solution (10.5 mL, 72 mmol) in an ice-water bath for 15 minutes. After the dropwise addition, the reaction mixture was continued to be stirred at the same temperature for 1 hour. At the end of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography to afford the title compound (2.5 g, 53% yield) as a yellow solid. ^1H-NMR (400 MHz, DMSO-d6) δ (ppm): 2.86 (s, 3H), 3.30 (s, 3H), 7.60 (d, J = 7.6 Hz, 2H), 7.95 (d, J = 7.6 Hz, 2H), 10.04 (s, 1H); LC-MS (ESI) m/z: 178 (M + 1)+.
