We have synthesized the first putative structure of gonioheptolide A by means of an exceptionally facile and surprisingly selective medium-ring lactonization under Corey-Nicolaou or Fischer conditions. Since the NMR and other spectroscopic data of the synthetic compound do not match that of the isolated material, it is likely that natural gonioheptolide does not feature a saturated eight-membered lactone as originally proposed. Biological evaluation of this unprecedented synthetic saturated eight-membered lactone is in progress.