Hydroxyl group deprotonation of the α and β anomers of methyl 3-O-benzyl-2,6-dideoxy-D-arabino-hexopyranoside (1and2) occurs readily in the gas phase to produce the corresponding anions3and4, respectively. Collisionally activated dissociation (CAD) of these anions causes fragmentation reactions that include ring opening, E2 elimination, and decarbonylation. Mechanisms for these reactions are proposed, and these mechanisms are supported by study of partially deuterated analogs of1and2.