Glycals, glycosidation

Methyl glycosides of 2 deoxy sugars have been prepared by the acid catalyzed addition of methanol to unsaturated sugars known as glycals... 

The glycal epoxide method turned out to be useful for the construction of complex 2-branched [3-aryl glycosides, which are salient features of the potent antibiotic vancomycin [75a]. Glycal epoxide glycosylation with sodium salts of indoles pro-... 

Oxathiins derived from the cyclic diacylthione (60) and glycals by a cycloaddition reaction yield glycosides on desulfurization, offering an alternative approach to glycosyl transfer <96AG(E)777>. 

K. Toshima, T. Ishizuka, G. Matsuo, and M. Nakata, Practical glycosidation method of glycals using montmorillonite K-10 as an environmentally acceptable and inexpensive industrial catalyst, Synlett (1995) 306-308. 

K. Toshima, N. Miyamoto, G. Matsuo, M. Nakata, and S. Matsumura, Environmentally compatible C-glycosidation of glycals using montmorillonite K-10, Chem. Commun., 11 (1996) 1379-1380. 

P. Tiwari, G. Agnihotriand, and A. K. Misra, Synthesis of 2, 3-unsaturated C-glycosides by HC104-Si02 catalyzed Ferrier rearrangement of glycals, Carbohydr. Res., 340 (2005) 749-752. 

R. J. Patch, H. Chen, and C. R. Pandit, Multivalent templated saccharides Convenient syntheses of spacer-linked 1, l -bis -and 1, 1, 1 "-tris-/i-glycosides by the glycal epoxide glycosidation method, /. Org. Chem., 62 (1997) 1543-1546. 

C-Glycosides.1 Reaction of an aldehyde with the diene 2 catalyzed by (R)-l results in dihydropyrones (3) in 80-97% ee, which can be converted to the glycals... 

These glycals react with trialkylaluminums to give C-glycosides (5), in which the /ram-isomer predominates. 

Comprehensive reviews of the chemistry of both the glycals [105-107] and anhydro sugars [108,109] have appeared in the recent literature. This chapter will attempt to summarize what is known about their preparation and reactivity in the formation of the glycosidic linkage and highlight recent examples to emphasize practical and strategic considerations in the choice of glycosyl donors. 

---