Active-latent glycosylations

In active-latent glycosylations, the glycosyl donor capability of an acceptor is turned on by a slight chemical modification in its aglycone. Glycosylation of the latent compound (106) by the active 

SCHEME 5.18 Armed-disarmed glycosylation based on torsional effects. 

As shown, the p-nitrophenyl thioglycoside (109) was glycosylated with the thiophenyl galactoside (110) to give the 3-(1 4) hnked disaccharide (111). Fucosylation of the free 0-3 with 

SCHEME 5.21 Synthesis of the Lewis pentasaccharide by active-latent glycosylation. 

---

SCHEME 5.23 Active-latent glycosylation using alkenyl glycosides,... 

SCHEME 5.24 Active-latent glycosylation using 2 -carboxybenzyl glycosides. Copyright 2006 by Taylor Francis Group LLC... 

Cao, S, Gan, Z, Roy, R, Active-latent glycosylation strategy toward Lewis X pentasaccharide in a form suitable for neoglycoconjugate syntheses, Carbohydr. Res., 318, 75-81, 1999. 

B. Using Novel Active-Latent Glycosylation Strategy to Produce Sialyloligosaccharides... 

Another versatile strategy, coined the active-latent glycosylation strategy, in which the reactivity of the carbohydrate luiits can be directly controlled by the agly-cone, together with the differential protection of the glycone itself, enabled the synthesis of various oligosaccharide donors [34,43-47]. 

S Cao. Active-Latent Glycosylation Strategy in Oligosaccharide and Glycoconjugate Syntheses. PhD dissertation, University of Ottawa, Ottawa, ON, Canada, 1996. 

SCHEME 5.24 Active-latent glycosylation using 2 -carboxybenzyl glycosides. 

Scheme 2 Early demonstration of the active-latent glycosylation strategy using sialic acid glycosides [22]...

In conclusion, the active-latent glycosylation strategy discussed above offers the possibility to prepare complex oligosaccharides by a highly convergent reiterative... 

In order to study further the usefulness of active-latent glycosylation strategy, we chose the synthesis of Lewis pentasaccharide which is widely distributed in many different human and animal tissues, and also in human milk oligosaccharides. 

---