Solution Conformation of Lonomycin Free Acid and Lonomycin Sodium Salt. An ¹H‐NMR Study

Abstract

SUMMARY.The conformations and relative configurations of the antibiotic Lonomycin free acid and its sodium salt have been revealed in a high resolution IH-nmr study in non polar solvents.The basic chair forms of the three pyrano'id rings have been confirmed although deformations are noted for ring B, heavily substitufied and possessing syndiaxial strain. The fixed rotarneric states around the acyclic fragments do not change by passing from the free to the complexed form. The extracted data suggest that the molecule possesses a rigid frame work forming a pseudocyclic backbone with a haid-to-tail buttoning shut by a hydrogen bond.INTRODUCTION.