Photoredox Chemistry of Sugars without Protecting Groups: Two-Step Production of C-Glycosides via Intermediate Dihydropyridine Glycosyl Esters

Unprotected sugars are converted directly into their corresponding dihydropyridine esters, which can be activated under photoredox conditions to produce glycosyl radicals, which in turn can react with a range of electron deficient alkenes to provide C-glycosides. This method does not involve any protection of sugar hydroxyl groups and represents a simple two-step method for the conversion of reducing sugars into unprotected C-glycosides.