Tethered glycosides

The IAD concept via p-methoxybenzylidene acetals was also shown to be suitable for polymer-supported syntheses of disaccharides (Scheme 5.107) [292], A suitable p-allyloxybenzyl group at position 2 of a 1-thio-mannosyl donor is first converted into a PEG-modified benzyl group that allows for the convenient isolation of the intermediate tethered glycosides. 

IAD via Silylene Tethering IAD through silylene-tethered glycosides was introduced by Bols [296-301] and Stork [302,303], The silylene tether is usually established by... 

Bols, M, Synthesis of koiitriose using silicon-tethered glycosidation, Acta Chem. Scand, 50, 931-937, 1996. 

Ziegler, T, Dettmann, R, AriffadhiUah, Zettl, U, Prearranged glycosides. 8. Intramolecular a-galactosylation via succinoyl tethered glycosides, J. Carbohydr. Chem., 18, 1079-1095, 1999. 

The tethered glycoside 381 underwent intramolecular transglycosylation to form the 1,4-linked mannoside 382 as an anomeric mixture a/p = 3.7 1) in moderate yield ( Scheme 62b). 

Ziegler T, Lemanski G, Hurttlen J (2001) Prearranged glycosides. Part 14 intramolecular glycosylation of non-symmetrically tethered glycosides. Tetrahedron Lett 42 569-572... 

Scheme 5. Solid-phase version of PMB-tethered glycosidation.

Scheme 8. Side-reaction in dimethylsilyl-tethered glycosidation.

Scheme 9. Dimethylsilyl-tethered glycosidation in the synthesis of a-glucopyranosides.

Scheme 11. Dimethylsilyl-tethered glycosidation with tethering to the 3 position of the donor.

Scheme 18. Stereodifferentiation in succinic acid-tethered glycosidation.

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