Isopropenyl glycosides as glycosyl donors

Although the methodology introduced by Sinay and advanced by Chenault does essentially work, glycoside synthesis using such vinyl ethers has no definite advantage over methods such as the trichloroacetimidate or n-pentenyl approaches detailed above and suffers from relatively non-trivial procedures required in the preparation of the donor species. However, a useful application of vinyl glycosides in oligosaccharide synthesis has subsequently been developed and applied successfully by Boons. 

2 A latent/active glycosylation strategy using vinyl glycosides 

One of the key features of Boons approach is the efficiency of the isomerization reaction. Early attempts to use Wilkinson s catalyst with a hindered base (DABCO) 

Latent/active strategy using vinyl glycosides isomerization of 3-buten-2-yl 2,3,4,6-tetra-O-benzyl-p-D-glucopyranoside [97]. 

Anhydrous tetrahydrofuran (THF) (2.5 cm, distilled from sodium/benzophenone) 

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