A One-Pot Synthesis of β-C-Glucopyranosides from exo-Glucal, p-Tolylsulfenyl Chloride, an α-Methoxyalkene, and an External Nucleophile

β-C-Glycosides were synthesized in one-pot experiments using the following sequence of four reactions:  (i) addition of p-TolSCl to an α-methoxyalkene, (ii) generation of the episulfonium ion from a β-(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.