[reaction: see text] Epoxide 4 is generated in situ from d-glucal-derived hydroxy mesylate 3. Reaction of epoxide 4 with a series of alkyl- and aryllithium reagents affords 2,3-unsaturated beta-C-glycosides with excellent 1,4-regioselectivity and complete stereoselectivity for the beta-glycoside. Other organometallic reagents demonstrate more complex behavior in their reactions with epoxide 4.