Recent advances in β-l-rhamnosylation.

l-Rhamnose forms the key components of important antigenic oligo- and polysaccharides of a variety of pathogens. Obtaining 1,2-cis stereoselectivity in the glycosylation of l-rhamnoside is quite challenging due to the unavailability of neighboring group participation and disfavoring of the anomeric effect and stereoelectronic effect of the substituents on the C-2 axial position. Nevertheless, various methodologies have been developed exploiting diverse pathways for obtaining β-stereoselectivity in the glycosylation of l-rhamnose. This review describes the recent advances in β-l-rhamnosylation and its applications in the total synthesis of β-l-rhamnose-containing biologically important oligosaccharides.