Fragmentation of isomeric dideoxy derivatives of 1,6-anhydro-β-D-hexopyranoses under electron impact

Electron impact mass spectra of all possible dideoxy derivatives of 1,6-anhydro-β-D-hexopyranoses and their sixteen specifically deuterium-labeled derivatives are reported. The spectra of positional isomers differ considerably making possible the reliable location of the hydroxyl group by mass spectrometry. The configuration of the hydroxyl group at C(2) and C(4) has only a negligible effect on the fragmentation pattern of stereoisomers. However, mass spectra of the C(3)-configurational isomers differ sufficiently to permit a stereochemical assignment. The fragmentation paths were elucidated by means of deuterium labeling and metastable spectra.