Synthesis of cinnamic esters and acids via palladium-catalyzed reactions of aryl diazonium salts and their biological evaluation

Abstract

A straightforward and efficient strategy has been established for the synthesis of cinnamic esters and cinnamic acids through the reaction of acrylic anhydride and aryl diazonium salts in a variety of solvents. The reaction to obtain cinnamic esters proceeds smoothly at room temperature in the presence of palladium acetate. In contrast, the formation of cinnamic acids requires basic conditions and is effectively achieved using K₂CO₃ at 80 °C in a DMF/H₂O solvent system. All the desired products were obtained in good yield. The approach offers several notable advantages, including operational simplicity, readily available and inexpensive starting materials, mild reaction conditions, and good product yields. The antioxidant potential of the synthesized cinnamic esters was assessed through radical scavenging activity (RSA) assays, along with their inhibitory effects on amyloid-β (Aβ) aggregation. Most compounds displayed a satisfactory range of RSA, while a subset of the derivatives exhibited moderate Aβ aggregation inhibitory activity.