Li+‐ and Ag+‐cationized per‐O‐acetyl‐ and Per‐O‐benzyl‐α‐ D ‐thioglycosides: a collision‐induced decomposition study

The collision‐induced decompositions of the [M + Li]+ and [M + Ag]+ ions of per‐O‐acetyl‐ and per‐O‐benzyl‐α‐D‐thioglycosides having phenyl sulphide, phenyl sulphoxide and phenyl sulphone as the aglycone moieties were studied. The [M + Li]+ ion of the acetyl derivative of the phenylthioglucoside shows loss of AcOLi, whereas its [M + Ag]+ ion shows elimination of PhSAg. Their sulphoxide and sulphone derivatives lose the C(1) and C(2) substituents to form the glucal under both Li+ and Ag+ cationization conditions. The corresponding benzyl derivatives do not show the loss of metal. The formation of glucal leads to ring fragmentation by retro‐Diels‐Alder reaction in the ring‐activated benzyl derivatives.