Synthesis. O-Glycosides

A recent improved preparation of l,6-epithio-/3-D-glucose (32) [33] and its selective opening at C-6 with a thioglucose such as (8a) [34] could be an interesting alternative method for the production of complex thiooligosaccharides since the resulting /J-thiodisaccharide (14f) can act as a donor in O-glycoside synthesis (Scheme 10). 

Wuhf, G, Rohle, G, Results and problems of O-glycoside synthesis, Angew. Chem. Int. Ed. Engl., 13, 157-170, 1974. 

As a result of recent progress in O-glycoside synthesis, a variety of new glycosyl donors and their specific activation methods are now available, some of which have also been applied to C-aiyl glycoside synthesis. Table 1 shows some examples for the coupling... 

O-Glycoside synthesis from 2-pyridylthio glycosides is also possible with O-benzyl-protected donors in the presence of methyl iodide [20], silver triflate [21 ], or mercuric salts [10,13,22]. The versatility of this leaving group has also been demonstrated in the synthesis of C-glycosides [23]. 

Bartolozzi A, Capozzi G, Menichetti S, Nativi C. Stereoselective 2-deoxy-p-O-glycoside synthesis based on remote activation of novel oxathiine donors. Eur. J. Org. Chem. 2001 2083-2090. 

Of the many methods described for glycoside synthesis, those predominantly used in current oligosaccharide synthesis, in which the glycosyl donor has O- or N- functionality at C-2 (that is, excluding 2-deoxyglycosides), are the following ... 

Synthesis of a number of O-glycosides (such as 131 -134) having different chain lengths between amino acids Ax and A10, which are part of interleukin-2, was accomplished by application of the Fmoc group in combination with the rm-butyl ester (77,78). 

Scheme 6.12 Rearrangement to C-aryl glycosides from aryl O-glycosides following a-selective synthesis using glycosyl phosphates.

Newer Observations on the Synthesis of O-Glycosides 1. Formation of Furanosides )... 

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