DITHIASUCCINOYL (DTS) AMINO-PROTECTING GROUP USED IN SYNTHESES OF 1,2-TRANS-AMINO SUGAR GLYCOSIDES

Suitable protected D-glucosamine derivatives possessing the N-dithiasu ccinoyl (N-Dts) protecting group of the amino function have been appli ed in a new alternative route to 1,2-transglycosylation. The eoxy-2-di thiasuccinoylamino-beta-D-glucopyranosyl) trichloroacetimidate 7 has b een used to prepare corresponding beta-glycosides in good yields promo ted by Lewis acids. The N-dithiasuccinoyl protecting group was easy to remove by thiolysis using 2-sulfanylethanol or dithiothreitol or redu ctively using sodium boranuide, thus affording, after N-acetylation, t he corresponding N-acetyl-beta-D-glucosamine glycosides. It has been d emonstrated that it is possible to reduce the Dts group in the presenc e of an azido group selectively by sodium boranuide or the Dts- and th e azido group simultaneously by dithiothreitol, using diisopropylethyl amine as a catalyst. The syntheses of the building blocks, N(a)lpha-Fm oc-Ser(Ac-3-beta-D Dts)-OPfp 10 and N(a)lpha-Fmoc-Thr(Ac-3-beta-D-GlcN Dts)-OPfp 11, suitable for the solid-phase glycopeptide synthesis of b eta-O linked GlcNAc bearing glycopeptides are described. Furthermore, the preparation of the c-3-beta-D-GlcNAc-(1-->4)-Ac-2-beta-D-GlcNAc]-O Pfp building block 19, suitable for the solid-phase synthesis of N-gly copeptides, and the synthesis of the beta-D-GlcNAc(1-->6 )-D-GalNAc di saccharide 27, a mucin core structure, demonstrate the use of N-dithia succinoyl protection in oligosaccharide synthesis.