ABSTRACT

N-Pentenyl Glycosides (NPGs) may be prepared directly by Fischer glycosidation of aldoses, or indirectly by most of the standard procedures for synthesizing alkyl glycosides. NPGs are stable at room temperature and are unaffected by most reagents and laboratory practices employed in carbohydrate transformations. However they react readily and chemospecifically with halonium ions under oxidative conditions that leave other alkenyl residues and oxidizable functional groups unaffected.N-lodo-succinimide/triethylsilyl triflate is highly recommended as the promoter, and under its agency, NPG reactions are usually complete within the time required to take a TLC sample. NPG activity can be sidetracked by bromination. The resulting vicinal dibromide is, in effect, a latent glycosyl donor since activity can be restored by reductive elimination.