A green and efficient synthesis of novel caffeic acid derivatives with Meldrum’s acid moieties as potential antibacterial agents

Abstract

Electrochemical oxidation of caffeic acid (1) has been studied in the presence of methyl and phenyl Meldrum's acids (3a–3b) as nucleophiles in water/acetonitrile (90/10) solutions using cyclic voltammetry and controlled-potential coulometry methods. The cyclic voltammetric results indicate that a one‐pot two‐step sequential reaction occurs between Meldrum's acids and the electrochemically derived o‐benzoquinone from the oxidation of caffeic acid and new caffeic acid derivatives with Meldrum's acid moieties (5a–5b) is formed. The mechanism of this reaction was suggested as an EC pathway using cyclic voltammetry, controlled-potential coulometry and spectroscopic data. In this work, we introduced the synthesis of new compounds with good yields and enhanced antibacterial activity through a catalyst‐free, environmentally friendly method at room temperature under green conditions. Furthermore, the antibacterial evaluation of caffeic acid (1), methyl and phenyl Meldrum's acids compounds (3a–3b) (as primary substances) in comparison with synthesized compounds (5a–5b) was performed by broth micro-dilution (or micro-dilution) method. Compounds (5a–5b) were found to be more effective against Gram ( −) and Gram ( +) bacteria than primary substances (1, 3a–3b).