The development of a method for direct dehydrative glycosylations with 1-hydroxyglycosyl donors employing the reagent combination of triflic anhydride and diphenyl sulfoxide is described. The one-pot coupling method is a facile process which is applicable to a variety of carbohydrate coupling partners. Oxygen-18-labeling studies are consistent with the first step in carbohydrate activation being the formation of an anomeric oxosulfonium intermediate. This reactive glycosyl species (35) is observable in low-temperature NMR experiments when 2,3,4,6-tetra-O-methyl-D-mannopyranose is activated as the glycosyl donor. When the dehydrative glycosylation reaction is performed in the presence of the triflic acid scavenger 2-chloropyridine, NMR analysis reveals that the glycosyl oxosulfonium intermediate 35 is converted to the corresponding anomeric 2-chloropyridinium species 36.
CITATION STYLE
Garcia, B. A., & Gin, D. Y. (2000). Dehydrative glycosylation with activated diphenyl sulfonium reagents. Scope, mode of C(1)-hemiacetal activation, and detection of reactive glycosyl intermediates. Journal of the American Chemical Society, 122(18), 4269–4279. https://doi.org/10.1021/ja993595a
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