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.