Structure Elucidation and Synthesis of (4S,5S,6Z,8E)-5-Hydroxydeca-6,8-dien-4-olide [(S,S)-Sapinofuranone B] - A Novel γ-Lactone Metabolite of Acremonium strictum.

The structure of (4S,5S,6Z,8E)-5-hydroxydeca-6,8-dien-4-olide, a novel metabolite of Acremonium strictum, has been established by spectroscopic studies and chemical correlation with the known L-factor. The structure has been confirmed by a total synthesis in which the asymmetric centres at C-4 and C-5 were elaborated from dimethyl L-tartrate and the 6,8-diene moiety was introduced via Stille coupling of (E)-prop-1-enyltributyltin with a (Z)-vinylic iodide. The absolute configurations of sapinofuranones A and B, recently isolated metabolites of Sphaeropsis sapinae, are shown to be the corresponding (4R,5S) and (4R,5R) diastereomers of the A. strictum metabolite.