Oligosaccharides are known to play important roles in many biological processes. In the study of oligosaccharides, collision-induced dissociation (CID) is the most common dissociation method to elucidate the sequence and connectivity. However, a disadvantage of CID is the decrease in both the degree and efficiency of dissociation with increasing mass. In the present study, we have successfully performed infrared multiphoton dissociation (IRMPD) on 39 O-linked mucin-type oligosaccharide alditols (both neutral and anionic). CID and IRMPD spectra of several oligosaccharides were also compared. They yielded nearly identical fragment ions corresponding to the lowest energy fragmentation pathways. The characteristic fragmentations of structural motifs, which can provide the linkage information, were similarly presented in both CID and IRMPD spectra. Multistage of CID (MS(3) or MS(4)) is commonly needed to completely sequence the oligosaccharides, while IRMPD of the same compounds yielded the fragment ions corresponding to the loss of the first residue to the last residue during a single-stage tandem MS (MS(2)). Finally, it is shown that the fragmentation efficiency of IRMPD increases with the increasing size of oligosaccharides.

Preparation of new polymer-supported electrophilic reagents that efficiently promote 1,2-haloacetoxylations of alkenes and alkoxyallenes is described. Under very mild conditions and in high yields, alkenes are transformed into r-halo acetates while alkoxyallenes lead to vinyl iodides. In contrast to these results, terminal alkynes commonly afford synthetically valuable 1-iodo-alkynes.Recently, development of polymer-supported reagents has been an area of intensive research. 1 Functionalized matrices can be used in excess to drive reactions in solution to completion and are finding application in high-throughput, automated parallel syntheses. 2 However, few polymersupported reagents that perform the 1,2-cohalogention 3 or epoxidation of alkenic double bonds have been described so far. 4 Our interest in new electrophilic halogen-ate(I) complexes 5 has led to the development of the first polymerbound iodine azide source which conveniently promotes azidoiodination of alkenes. 6 As a continuation of this work we describe the preparation of three resin-bound synthetic equivalents of acylated hypohalites and demonstrate that they are powerful electrophilic reagents for the selective oxidation of alkenes, alkynes, and alkoxyallenes. † Technischen Universität Clausthal.