Glycosylation vinyl glycosides

Boons G-J, Isles S. Vinyl glycosides in oligosaccharide synthesis (part 1) a new latent-active glycosylation strategy. Tetrahedron Lett. 1994 35 3593-3596. 

SCHEME 4.31 Vinyl glycosides in latent-active glycosylation. 

Bai, Y, Boons, G-J, Burton, A, Johnson, M, Haller, M, Vinyl glycosides in oligosaccharide synthesis (part 6) 3-buten-2-yl 2-azido-2-deoxy glycosides and 3-buten-2-yl 2-phthalimido-2-deoxy glycosides as novel glycosyl donors, J. Carbohydr. Chem., 19, 939-958, 2000. 

Boons, G J, Heskamp, B, Hout, F, Vinyl glycosides in ohgosaccharide synthesis a strategy for the preparation of trisaccharide hbraries based on latent-active glycosylations, Angew. Chem. Int. Ed. Engl, 35, 2845-2847, 1996. 

Isopropenyl glycosides could be activated selectively in the presence of armed NPGs, and that allowed a one-pot synthesis of trisaccharide 322 involving the successive glycosyl coupling of a vinyl glycoside jS-307, and an NPG, 321 (O Scheme 52). 

The allyl glycoside 323, can be considered a latent [177] form of a glycosyl donor which can be efficiently isomerized to the active vinyl glycoside, 324. The isomerization reaction was performed by a rhodium catalyst obtained by treating the Wilkinson s catalyst, (Ph3)P3RhCl,... 

Vinyl glycoside-based latent-active strategy for glycosyl coupling... 

Treatment of active vinyl glycosides with NIS/TMSOTf in CH2CI2 in the presence of dibenzyl phosphate gives good yield of glycosyl phosphates [184]. 

Several C-glycosylated amino acids were obtained by 13-DC of (-)-menthonc-derived chiral nitrone (-)-90 and allyl- or vinyl glycosides. For instance the cycloaddition of (-)-90 and 91 occurred with complete diastereo- and regioselectivity to afford the isoxazolidine 92 in 92% yield. The a-amino acid moiety was then obtained by Sm(ll) mediated cleavage of the N-O bond followed by fV -acetal and amide hydrolysis <01OL1375>. 

The application of vinyl glycosides as glycosyl donors has, overall, been less successful than that of trichloroacetimidates or n-pentenyl glycosides. However, several different approaches have been taken by a number of different research groups and the work of Boons and co-workers in particular has led to some useful methodology with general applicability in oligosaccharide assembly. 

A latent/active glycosylation strategy using vinyl glycosides... 

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