Total synthesis of (+)-phenguignardic acid, a phytotoxic metabolite of Guignardia bidwellii

摘要

(+)-Phenguignardic acid, a phytotoxic metabolite of the grape black rot fungus Guignardia bidwellii was synthesized, as well as its enantiomer, in eight steps from (R)-phenyllactic acid and 3-phenylprop-2-yn-1-ol. The formation of the carboxylate at a late stage, to avoid enolization of the precursor used in the central acetalization step, proved to be crucial. The synthesis of the natural product allowed the unabiguous assignment of its hitherto unknown absolute configuration. (+)-Phenguignardic acid, a potent phytotoxic metabolite of Guignardia bidwellii, was synthesized, as well as its enantiomer, in eight steps from (R)-phenyllactic acid and 3-phenylprop-2-yn-1-ol. The absolute configuration of the natural product was determined to be S.