Collect. Czech. Chem. Commun. 1999, 64, 703-709

Acetal Formation is Responsible for the Non-Closed Form of Monensin A in Methanolic Solution

Petr Sedmera* and Stanislav Pospíšil

Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague 4, Czech Republic


NMR evidence shows that so-called non-closed form of monensin A free acid reported to exist in methanol is in fact due to acetal formation at C-25. The 25-alkoxy derivatives retain this conformation even in non-polar media.

Keywords: Polyether antibiotics; Ionophores; Monensin A; Methyl acetal formation; Conformational analysis; NMR spectroscopy, 1H, 13C.