New Stereoselective β-C-Glycosidation by Uncatalyzed 1,4-Addition of Organolithium Reagents to a Glycal-Derived Vinyl Oxirane

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 β-C-glycosides with excellent 1,4-regioselectivity and complete stereoselectivity for the β-glycoside. Other organometallic reagents demonstrate more complex behavior in their reactions with epoxide 4.