Abstract
| - Novel 15-membered macrolides possessing the dilactone skeleton, diolides 13a and 13b, have beensynthesized in our research program aimed at finding new antibacterial macrolides. Key strategicelements of the approach include the ring-expanding reaction of 13-membered dilactones, preparedfrom erythromycin A (Ery-A), to 15-membered dilactones via intramolecular translactonization.The absolute configuration at the regenerated C-8 position of the new diolides was determined bychemical transformation, leading to the corresponding lactam analogues, whose stereochemistryis known in the literature. For further confirmation, X-ray analysis was performed. The X-raystructure determination of 13a revealed a backbone conformation similar to that of Ery-A. Novel15-membered diolide 13a and the 11,12-diol 18 exhibited antibacterial activities comparable tothat of Ery-A.
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