Synthesis and Biological Activity of Estafiatin Phosphonate Derivatives

Four new dialkylphosphonate derivatives 2–5 were prepared for the first time from the guaiane-type sesquiterpene lactone estafiatin (1), which was isolated from the aerial part of Achillea nobilis. Their structures were elucidated using PMR, 13C NMR, two-dimensional 1H–1H COSY, 13C–1H COLOC, and 31P–1H spectroscopy. The estafiatin phosphorylation reaction was highly chemo- and stereoselective. The antimicrobial activity of the prepared derivatives was studied.