Monensin chemical structure

Fig. 2. Chemical structures of monensin (a) and cholanic acid (b). (Cited from Ref.8))...

Figure 1. X-ray crystal structure of the monensin-Ag complex (reprinted with permission from the American Chemical Society J. Am. Chem. Soc. 1967, 89, 5737).

A conformational analysis of naproxen anion and monensin sodium has been performed by the use of the /hc couplings. Especially extensive use of these couplings has been made by the authors in the case of the latter compound. They concluded that the conformation of monoensin in solution is very close to that in crystals. Further examples of the application of vicinal proton-carbon couplings in the conformational analysis of compounds include the NMR and quantum-chemical study of the stereochemistry of spiroepoxides obtained by oxidation of (Z)-3-arylidene-l-thioflavan-4-ones performed by Toth et and the elucidation of the structure of isomalyngamides A and B isolated from a collection of the cyanobacterium Lyngbya majuscula from Hawaiian waters by Kan et... 

Because of the complexity of the polyether antibiotics little progress has been made in structure determination by the chemical degradation route. X-ray methods were the techniques most successfully applied for the early structure elucidations. Monensin, X206, lasalocid, lysocellin, and salinomycin were included in nineteen distinct polyether x-ray analyses reported in 1983 (190). Use of mass spectrometry (191), and 1H (192) and 13C nmr (141) are also reviewed. More recently, innovative developments in these latter techniques have resulted in increased applications for structure determinations. For example, heteronuclear multiple bond connectivity (hmbc) and homonudear Hartmann-Hahn spectroscopy were used to solve the structure of portimicin (14) (193). Fast atom bombardment mass spectrometry was used in solving the structures of maduramicin alpha and co-factors (58). 

---