An attempt has been made to predict qualitative trends in reactivity at the anomeric center, using N-bromosuccinimide-induced hydrolysis of n-pentenyl glycosides (NPGs) as the experimental model. Calculated relative activation energies based on internal energy differences between a reactant and the associated intermediate are not always in agreement with experimental observations. However, solvation energies obtained by the generalized Born surface area model in MacroModel developed by Still et al. give modified activation energies that are in excellent agreement with the experimentally observed trends. It is shown that the solvation model does not disturb the normally observed reactivity trends that can be rationalized on the basis of internal energies alone. The value of the methodology has been demonstrated for several substrates by first calculating their relative activation energies, then testing them experimentally, and finding excellent agreement with predictions. 5280

Recent synthetic efforts in the construction of oligosaccharides, glycoproteins, glycolipids and other glycoconjugates containing a variety of 2‐amino‐2‐deoxy sugars have led to the development of new methods for nitrogen protection. These new nitrogen‐protecting groups have been removed from substrates using mild and often chemoselective conditions. In this microreview, the preparation, present uses, and deprotection of amino sugar derivatives employing these new agents are described. Applications of phthalimides with electron‐withdrawing groups including the tetrachlorophthaloyl (TCP), dichlorophthaloyl (DCPhth), dithiasuccinoyl (Dts), N‐pent‐4‐enoyl and N,N‐diacetyl functionalities are discussed.

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