Synthesis of the structures proposed for natural butanolides piliferolides A and C

The structures proposed for natural butanolides piliferolides A and C have been synthesized. The allylic and lactone stereogenic centers in the target structures were derived from d-mannitol, while that near the side-chain terminal was taken from (R)-propylene oxide. The synthetic samples helped to reveal that a signal at around δ 2.0 ppm was missing in the 1H NMR data listing for the structures proposed for natural piliferolides, whereas the δ 29.7 ppm signal in the 13C NMR reported for the structure proposed for natural piliferolide C most likely stemmed from the impurities in the chromatography solvent.