Solution Conformations of Dianemycin, its Sodium Salt and of Lenoremycin‐Na⁺ (Ro 21‐6150 or A‐130‐A)

Abstract

Abstract Extensive nmdr experiments in the 300 MHz 1 H‐nmr spectra of the title compounds in different solvents allows the conformational description of these pseudocyclic ionophores. There is a striking similarity between the present results and the solid state data for the salts. The free acid form of dianemycin possesses in solution the cyclic form wherein the cation is ultimately held in the salt. Stereoscopic views are presented (Figures 9 ‐ 11). The possible role of the sugar‐like moieties is discussed and a mechanism for trapping is tentatively proposed. Both membrane‐active complexones seem rather primitive representatives of the nigericin family, but lenoremycin offers a more sophisticated topography, the extra side‐ring possessing probably a multiple function.