Activations trichloroacetimidates

PTFAs are generally less reactive than the corresponding trichloroacetimidate donors presumably because of the lower N-basicity or the presence of an N-sub-stituent. Although most trichloroacetimidate activators could also be used to promote PTFA glycosidations, such as TMSOTf [384], BF3Et20 [384,547], TBSOTf [548], Yb(OTf)3 [549,550] and acid-washed molecular sieves [551], the activation of PTFA usually requires more forceful conditions. Several representative Lewis-acid-catalyzed PTFA glycosidation reactions are listed m Scheme 3.58. It is worth... 

ANOMERIC-OXYGEN ACTIVATION FOR GLYCOSIDE SYNTHESIS THE TRICHLOROACETIMIDATE METHOD... 

Anhydrous hydrogen fluoride, application of for the structural analysis of polysaccharides, 47, 167-202 Anomeric and exo-anomeric effects in carbohydrate chemistry, 47, 45-123 Anomeric-oxygen activation for glycoside synthesis, trichloroacetimidate method, 50,21-123... 

Glycopeptides containing glycosyl L-aspara-gine, L-serine, and L-threonine, developments in, 50,277-310 Glycoside hydrolases, mechanistic information firm studies with reversible and irreversible inhibitors, 48, 319-384 Glycoside synthesis, anomeric-oxygen activation for (trichloroacetimidate method), 50,21 -123... 

Trichloroacetimidate method, anomeric-ox-ygen activation for glycoside synthesis, 50,21-123... 

Thioglycosides were the first example of an anomeric derivatization that serves the dual role of protection and activation. They were introduced in glycosylation reactions by Ferrier et al. in 1973, who used mercury(II) salts as activator.1 After the development of improved methods of their synthesis and activation, thioglycosides together with trichloroacetimidates are now the most commonly used glycosyl... 

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