Nitrogen transfer to glycals: A new method for direct C2-aza-glycosylation with glycal donors has been developed (see scheme), employing the new reagent combination of thianthrene-S-oxide and trifluoroacetic anhydride for glycal activation, in an overall one-pot procedure.
[Show abstract][Hide abstract] ABSTRACT: The direct stereoselective I111-mediated ocidative ring contraction of a protected 6-deoxy-D-gulal substrate to form a highly functinalized tetrahydrofurfural intermediate is a key step in the first total synthesis of (+)-pyrenlide D (see scheme; R = TBS = tert-butyldimethylsilyl).
[Show abstract][Hide abstract] ABSTRACT: Β-D-Ribofuranosyl-(1→3)-α-L-rhamnopyranosyl-(1→3)- L-rhamnopyranose, the trisaccharide repeating unit of the C. freundii O28, 1c O-specific polysaccharide, was synthesized using in situ activating glycosylation of the 1-OH sugar derivatives and a reagent mixture of trimethylsilyl bromide, cobalt(II) bromide, tetrabutylammonium bromide, and molecular sieves 4A. Regioselective tritylation was useful for synthesizing the 3-OH derivatives of methyl, allyl, and benzyl α-L-rhamnosides.
Bulletin of the Chemical Society of Japan 09/2001; 74(9):1679-1694. DOI:10.1246/bcsj.74.1679 · 2.21 Impact Factor
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