ABSTRACT
Generally, mass spectrometry offers a rapid means of structure elucidation, provided that the new compound can be related to a known class, e.g., in metabolism studies or by inspection of the mass spectrum. To date, mass spectrometry has not been used to provide stereochemical information about polyether antibiotics. Apart from speed, mass spectrometry offers to the investigator the advantage of being able to successfully examine impure and noncrystalline samples. Mixtures can be separated in the direct probe of the mass spectrometer by thermal fractionation or resolved mass-spectrometrically by high-resolution analysis of ions with the same nominal mass. Similar analysis of NMR and EI spectrometry showed that the two other microbial transformation products were N-demethyl A23187 methyl ester and 16-hydroxy-N-demethyl A23187 methyl ester. Kitame and Ishida made use of the mass spectrometry and NMR spectroscopy in deducing the structure of laidlomycin.
