LI-CATIONIZED AND AG+-CATIONIZED PER-O-ACETYL-ALPHA-D-THIOGLYCOSIDES AND PER-O-BENZYL-ALPHA-D-THIOGLYCOSIDES - A COLLISION-INDUCED DECOMPOSITION STUDY()

The collision-induced decompositions of the [M + Li]+ and [M + Ag]+ io ns of per-O-acetyl- and per-O-benzyl-alpha-D-thioglycosides having phe nyl sulphide, phenyl sulphoxide and phenyl sulphone as the aglycone mo ieties were studied. The [M + Li]+ ion of the acetyl derivative of the phenylthioglucoside shows loss of AcOLi, whereas its [M + Ag]+ ion sh ows elimination of PhSAg. Their sulphoxide and sulphone derivatives lo se the C(1) and C(2) substituents to form the glucal under both Li+ an d Ag+ cationization conditions. The corresponding benzyl derivatives d o not show the loss of metal. The formation of glucal leads to ring fr agmentation by retro-Diels-Alder reaction in the ring-activated benzyl derivatives.