Synthesis
General method: p-phenylbenzaldehyde (0.1 mol) and glacial acetic acid (0.1 mol) were dissolved in dichloromethane (15 mL) under nitrogen protection, followed by the addition of titanium tetrachloride (TiCl4, 0.21 mol). The reaction mixture was stirred at room temperature for 20 min. Subsequently, triethylamine (Et3N, 0.25 mol) was slowly added dropwise over 10 minutes, and the reaction continued to be stirred at room temperature for 3-4 hours after the drop was completed. The progress of the reaction was monitored by thin layer chromatography (TLC) and after confirming the completion of the reaction, the organic layer was separated by adding water (25 mL) to dilute the reaction mixture. The organic phase was dried with anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure to afford (E)-4-phenylcinnamic acid (1) in high purity and yield.
References
[1] Tetrahedron Letters, 2014, vol. 55, # 24, p. 3503 - 3506
