THE CHEMISTRY OF N-PENTENYL GLYCOSIDES - SYNTHETIC, THEORETICAL, AND MECHANISTIC RAMIFICATIONS

A feature of N-pentenyl glycosides (NPGs) is the ability to dibrominate the pentenyl double bond and, subsequently, regenerate it by reductive elimination. This allows a given NPG to serve (a) immediately as a glycosyl donor, or (b) after dibromination, as a glycosyl acceptor and, after subsequent reductive elimination as a glycosyl donor. These properties have been exploited to develop methodology for rapid assembly of homoglycans. Based upon results from the oxidative hydrolysis of conformationally restrained NPGs, ab initio calculations to determine transition states of protonated axial and equatorial 2-methoxytetrahydropyran have been undertaken. The relevance of our results to the theory of stereoelectronic control (antiperiplanar lone pair hypothesis) and to the action of lysozyme is discussed.