Alpha- and beta-glycosyl sulfonium ions: generation and reactivity
Toshiki Nokami1, Akito Shibuya, Shino Manabe
1Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
Abstract:
Low-temperature electrochemical oxidation of thioglycosides gave glycosyl triflates from which glycosyl sulfonium ions were produced (see scheme). The latter were characterized by NMR spectroscopy and cold-spray mass spectrometry as a mixture of alpha- and beta-isomers (45:55). The alpha-glycosyl sulfonium ion exhibited higher reactivity than the beta-glycosyl sulfonium ion in the reaction with methanol, which gave a mixture of alpha- and beta-methyl glycosides (41:59).
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