Glycoside synthesis, tuning donor reactivity

D. Kahne et al. developed a one-pot multicomponent stereoselective synthesis for the trisaccharide portion of cyclamycin 0 using the Kahne glycosidation.The reactivity of the glycosyl donor was tuned (the rate limiting step is the triflation of the sulfoxide) and the p-methoxyphenyl sulfoxide was activated first. The trisaccharide was obtained in an overall 25% yield with complete a-selectivity. 

Notes and discussion. The power of modern glycosidation methods was demonstrated by combining an orthogonal (F versus SePh) and a reactivity tuning (see Chapter 6) approach. In a one-pot, four step reaction, a pentasaccharide was formed in 8% yield from donor 31 [20]. Further applications in efficient oligosaccharide synthesis have also been reported [20, 21, 23-25]. 

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