Synthesis and DPPH radical scavenging activity of novel compounds obtained from tyrosol and cinnamic acid derivatives

Tyrosol, a naturally occurring phenolic compound poorly attractive as an antioxidant because of its weak efficacy, was used as starting material to obtain novel compounds. The synthesis is based on a trifluoroacetic acid-mediated hydroarylation of cinnamic esters with tyrosol to produce 4-aryl-3,4-dihydrocoumarins, molecules of biological interest, followed by a basic hydrolysis to give the corresponding ring opening products. Unreported mechanistic investigations confirmed that the first step resulted from an electrophilic aromatic substitution and an intramolecular transesterification. Final products exhibited DPPH radical scavenging activity significantly higher than tyrosol.