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1 -Selenoglycosides synthesis

Scheme 3.6 Stick s phenyl selenoglycoside synthesis (i) PhSeSePh, NaBH4, EtOH, 2h,... Scheme 3.6 Stick s phenyl selenoglycoside synthesis (i) PhSeSePh, NaBH4, EtOH, 2h,...
Selenoglycosides have also emerged as valuable intermediates in oligosaccharide synthesis. Thus, the following has been described for phenyl selenoglycosides189 ... [Pg.199]

Such a synthesis is shown in Scheme 4.18a, in which a glycosyl bromide is coupled with the thioglycosyl acceptor to afford a thioglycosyl disaccharide. The glycosyl bromide was obtained from the corresponding 1-thioglycoside by treatment with Br2. It was shown [222-224] that phenyl selenoglycosides can be selectively activated in the... [Pg.228]

Dehydrativeglycosylation of 1-hydroxy donors with Ph2S0/Tf20 in conjunction with thioglycoside acceptors opens the way for sequential double glycosylation, one-pot procedures for trisaccharide synthesis, as exemplified by the efficient one-pot synthesis of the a-Gal epitope and a hyaluronan trisaccharide [566]. This study also shows the potential of selenoglycoside as acceptors in dehydrative glycosylation (Scheme 4.112). [Pg.316]

Exploiting Selenoglycoside Relative Reactivity in Oligosaccharide Synthesis... [Pg.317]

In conclusion, the phenyl selenoglycosides are versatile building blocks for oligosaccharide synthesis. Through judicious choice of protecting groups, and particularly promoters, they can be exploited as either donors or acceptors in glycosylation... [Pg.320]

Ley and coworkers reported the one-pot synthesis of tetrasaccharide 176 by combining selective activation with reactivity-based armed-disarmed glycosylation [113]. As shown in Scheme 6.35, the first chemoselective coupling was achieved via selective activation of the fluoride donor 173 over the selenoglycoside acceptor 174. The resulting disaccharide intermediate was more armed than the bifunctional... [Pg.179]

It is noteworthy that all of the methods for the synthesis of selenoglycosides mentioned lead preferentially to the formation of the 1,2-trans prod-... [Pg.146]

III. Application of Seleno Sugars in Synthesis 1. Utilization of Selenoglycosides in Glycosylation Reaction... [Pg.167]

Some disappointing results were reported later by the same group in an attempt to use phenyl selenoglycoside donors for the synthesis of a tetrasaccharide.86 No glycosylation was possible with phenyl selenoglycoside 193 in the presence of NIS-TfOH, whereas 40% yield was obtained with the corresponding trichloroacetimidate 194. [Pg.173]

Mehta, S, Pinto, B M, Novel glycosidation methodology. The use of phenyl selenoglycosides as glycosyl donors and acceptors in oligosaccharide synthesis, J. Org. Chem., 58, 3269-3276, 1993. [Pg.195]

S. Yamago, T. Yamada, O. Hara, H. Ito, Y. Mino, and J. Yoshida, A new, iterative strategy of oligosaccharide synthesis based on highly reactive /J-bromoglycosides derived from selenoglycosides, Org. Lett., 3 (2001) 3867-3870. [Pg.242]

Strong preferential activation of 1 -telluroglycosides is possible in the presence of of the corresponding 1-selenoglycoside by using IV-iodosuccinimide as promoter. This further extends the possibilities for selective glycosylation reactions in oligosaccharide synthesis.175... [Pg.104]


See other pages where 1 -Selenoglycosides synthesis is mentioned: [Pg.307]    [Pg.308]    [Pg.200]    [Pg.306]    [Pg.308]    [Pg.312]    [Pg.313]    [Pg.314]    [Pg.315]    [Pg.317]    [Pg.317]    [Pg.320]    [Pg.258]    [Pg.452]    [Pg.69]    [Pg.163]    [Pg.167]    [Pg.331]    [Pg.173]    [Pg.120]    [Pg.214]    [Pg.431]    [Pg.233]    [Pg.664]    [Pg.199]    [Pg.256]    [Pg.31]    [Pg.101]    [Pg.196]    [Pg.416]    [Pg.274]   
See also in sourсe #XX -- [ Pg.103 ]




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