Zweifel olefination for C-glycosylation.

C-glycosides are significant in medicinal chemistry due to their resistance to enzymatic hydrolysis, making them more stable and bioavailable compared to O-glycosides. Their unique structure also offers potential for developing drugs with improved therapeutic properties, particularly in treating diseases like diabetes and cancer. The main challenge in synthesizing C-glycosides lies in forming the carbon-carbon bond between the sugar and aglycone efficiently, while controlling the stereochemistry and minimizing side reactions. Starting from glycal derivatives, the Zweifel olefination presents an elegant opportunity to access C-glycosides in a selective manner. α-Lithiation of D-glucal, L-rhamnal, D-xylal and L-arabinal scaffolds was employed as a starting point in the synthesis of corresponding unsaturated aryl-, heteroaryl- and alkenyl-C-glycosides. This provides a straightforward strategy towards pharmacorelevant gliflozins and other unreported rhamnal- and xylal-analogs.