Synthesis of low-valency neoglycoconjugates using transition metal-catalyzed reactions and synthesis of phenylethanoid glycosides.

Abstract

In the first part of this thesis, a series of rigid glycodimers were synthesized from sugar alkenes and alkynes, using transition metal catalyzed reactions. The synthesis of these dimers depended on the formation of a new carbon-carbon bond between their monomeric units. Sugars containing terminal alkenes were homodimerized using the olefin metathesis reaction, catalyzed by Grubbs' ruthenium catalyst. Terminal alkene carbohydrate derivatives were also coupled with aryl halide carbohydrates by the Heck coupling reaction, using Pd (0) catalyst, to form homo- and hetero-carbohydrate dimers selectively. Glycodimers were also obtained from sugar alkynes, using the Sonogashira coupling reaction. The dimerization of aryl halide carbohydrate derivatives using Pd (0) catalyst, and the cyclotrimerization of alkyne carbohydrates, using Grubbs' catalyst, were also attempted but were not successful. In the second part of this thesis, phenylethanoid glycosides were synthesized by glycosidation reactions. This family of compounds was shown to have numerous biological activities. A multi-step synthesis of Echinacoside, a phenylethanoid glycoside, was attempted.