Synthesis, Structure, Properties, and Antimicrobial Activity of Dialkyl(hydroxy(4-methoxyphenyl)methyl)phosphonates

Abstract Objective: A series of dialkyl (hydroxy(4-methoxyphenyl)methyl)phosphonates 1–5 with various substituents at the phosphorus atom was obtained via the Abramov reaction. Methods: The structure of the isolated products was confirmed by a set of physicochemical methods: NMR, FT-IR spectroscopy, and X-ray diffraction analysis. The phytotoxicity of the obtained compounds was evaluated against radish (Raphanus sativus L.) and common wheat (Triticum aestivum L.). Ecotoxicity indices against the cladoceran C. affinis and the protozoan P. caudatum were determined. The antibacterial and antimycotic activity of the synthesized α-hydroxyphosphonates was investigated. TG and DSC analyses were performed. Results and Discussion: The prospects of studying compound 1 as an herbicide are shown. It was found that compounds 2–5 exhibited activity against P. vulgaris, K. pneumoniae, and S. typhimurium. Compounds 4 and 5 inhibited B. cereus and S. aureus. Antimycotic activity correlated with the length of the alkoxyl substituent at the phosphorus atom: with increasing substituent length, activity against Candida fungi and the microscopic fungus S. cerevisiae was manifested. TG and DSC analyses showed that the first stage of decomposition of the compounds is associated with β-elimination of alkyl groups to form hydroxymethylphosphonic acids, while the second stage corresponds to the elimination of the aromatic fragment. Above 480°C, intermolecular condensation with elimination of water is observed for all compounds. Conclusions: A series of dialkyl(hydroxy(4-methoxyphenyl)methyl)phosphonates 1–5 were obtained via the Abramov reaction and characterized. Compounds 2–5 showed antibacterial activity, with activity depending on the alkoxyl chain length, and increasing chain length also promoted antifungal action. All compounds were less toxic than chlorhexidine, while compound 1 showed phytotoxicity against radish and wheat, indicating prospects for its study as an herbicide.