Glycosidation methods

I. General Introduction Glycosidation Methods for Oligosaccharide Synthesis. .. 178... 

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. 

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. 

This glycosidation methods dates back to 1901 [5]. As in all glycosidation reactions, this method achieves activation of the anomeric center by decomposition of glycosyl halides, normally bromides and chlorides, in the presence of heavy metals (usually silver or mercury). Scheme 1 depicts the general mechanism of this reaction which involves in situ... 

Scheme 5 The n-pentenyl glycoside-based glycosidation method, (E+ = l(collidine)2CI04) [17].

Several other glycosidation methods can also be considered as proceeding by remote activation. For example, treatment of 0-benzyl glycosyl trichloroacetimidates with BFj-EtjO [2 see also Chap. 11], or 0-benzyl pentenyl glycosides with NBS [19 see also Chap. 13] leads to activation at an atom not directly attached to the anomeric center. 

K. Toshima, G. Matsuo, T. Ishizuka, Y. Ushiki, M. Nakata, and S. Matsumura, Aryl and allyl C-glycosidation methods using unprotected sugars, J. Org. Chem., 63 (1998) 2307-2313. 

J. Janson and B. Lindberg, Alkyl glycosides by alkaline transglycosylation of aryl glycosides, Methods Carbohydr. Chem., 2 (1963) 374-375 and references therein. 

Hashimoto, S, Honda, T, Ikegami, S, A mild and rapid 1,2-tranr-glycosidation method via benzoyl-protected glycopyranosyl R,R-diphenyl-iV-(p-toluenesulfonyl)phosphinimidates, Heterocycles, 30, 775-778, 1990. 

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