Stereochemical effects in mass spectra—Studies on mass spectra of epimers of podophyllotoxin and its derivatives

Mass spectra of thirteen epimers of podophyllotoxin and its derivatives have been examined. By means of high resolution mass spectrometry, metastable ion scanning and isotopelabeling techniques, the effects of configuration of C₁-OH and condensed lactone ring on the fragmentation pattern and the relative abundances of characteristic ions in the mass spectra of these compounds have been studied and rationalized.