ELECTRON IONIZATION MASS-SPECTRA OF MONOSACCHARIDE O-METHYLOXIME TRIFLUOROACETATES

Electron ionization mass spectra for trifluoroacetate (TFA) derivatives of aldose, ketose, and deoxyaldose O-methyloximes are reported. Typical fragmentation patterns include loss of F, CH3O, CF3CO, or CF3CO2 fragments from the generally observable parent ion, as well as cleavage between each of the sugar CC chain bonds. The most intense ions result from loss of trifluoroacetic acid and/or trifluoroacetic anhydride from these primary fragments. Suitable high-mass and fragmentation ions are present to make this technique a useful structural probe. During the preparation of fructose TFA O-alkyloximes, partial conversion to 1-chloro-1-deoxyfructose derivatives is observed due to displacement of an O-trifluoroacetyl group by chloride ions present in the reaction mixture. © 1990.