Studies on the Chemical Modification of Monensin. I. Synthesis and Crystal Structures of NaBr Complexes of Monensylamino Acids

Abstract

Condensation of the polyether antibiotic monensin (with amino acid benzyl esters followed by debenzylation gave monensylamino acids (3a—g), which were subsequently converted to the corresponding NaBr complexes (4a—g). An X-ray crystallographic study on 4e clarified that the conformation of 4e differs from that of the NaBr complex of monensin (in that an intramolecular hydrogen bond is present between 0(oxygen and 0(1 hydroxy proton. This finding is consistent with the carbon-13 nuclear magnetic resonance signals of the methoxy carbons of 4a— g which appear downfield relative to those of 3a—g. Compounds 3a—g showed no anticoccidial activity. © 1988, The Pharmaceutical Society of Japan. All rights reserved.