A one-pot synthesis of beta-C-glucopyranosides from exo-glucal, p-tolylsulfenyl chloride, an alpha-methoxyalkene, and an external nucleophile.

[formula: see text] beta-C-Glycosides were synthesized in one-pot experiments using the following sequence of four reactions: (i) addition of p-TolSCl to an alpha-methoxyalkene, (ii) generation of the episulfonium ion from a beta-(arylsulfanyl)alkyl chloride, (iii) reaction of the episulfonium intermediate with benzylated exo-D-glucal to form a cyclic five-membered sulfonium salt, and (iv) quenching of the sulfonium salt with the external nucleophile: H2O, CH3OH, or NaCNBH3.