Expeditious oligosaccharide synthesis via selective, semi-orthogonal, and orthogonal activation

Abstract

Traditional strategies for oligosaccharide synthesis often require extensive protecting and/or leaving group manipulations between each glycosylation step, thereby increasing the total number of synthetic steps while decreasing the efficiency of the synthesis. In contrast, expeditious strategies allow for the rapid chemical synthesis of complex carbohydrates by minimizing extraneous chemical manipulations. Oligosaccharide synthesis by selective activation of one leaving group over another is one such expeditious strategy. Herein, the significant improvements that have recently emerged in the area of the selective activation are discussed. The development of orthogonal strategy further expands the scope of the selective activation methodology. Surveyed in this article, are representative examples wherein these excellent innovations have been applied to the synthesis of various oligosaccharide sequences.

Automated Chemical Synthesis of Oligosaccharides and Glycoconjugates

“…Takahashi and co-workers probed a number of automation platforms for the solution-based one-pot oligosaccharide synthesis [133]. In a majority of applications, selective activation of different leaving groups, another common approach to expeditious oligosaccharide synthesis [53,67], was executed. For instance, a parallel synthesis instrument, Quest 210 by Argonaut Technologies, was applied to the automated one-pot synthesis of linear and branched oligosaccharides shown in Fig.…”

“…A few relevant examples include Fraser-Reid's armed-disarmed approach [54][55], Nicolaou's selective activation [56], Danishefsky's glycal-based assembly [57], Kahne's one-pot synthesis [58], Roy's [59] and Boons' [60] active-latent concept, Ogawa's orthogonal strategy [61][62], Huang's preactivation concept [63][64][65], etc. [66][67][68].…”

Glycosyltransferase engineering for carbohydrate synthesis

“…Several other assays for GT activity measure nucleotide sugar depletion or nucleotide diphosphate formation [3–7]. These types of assays are appealing because they are universal for all GT reactions that use nucleotide diphosphate-sugars.…”

From Stereocontrolled Glycosylation to Expeditious Oligosaccharide Synthesis

“…A number of selective activation techniques have been developed and selective activation, active-latent, and orthogonal strategies are only few to mention (65). Our group studied both chemoselective and selective activation-based strategies.…”