Synthesis of terminal disaccharide unit of Klebsiella pneumoniae ssp. R20

Synthesis of the terminal disaccharide unit of a novel α-(1→2) linked heptoglycan of K. pneumoniae ssp. strain R20 from methyl α-d-mannopyranoside has been presented. Central to the strategy is the application of Sharpless asymmetric dihydroxylation to introduce a new center at C-6 position of mannopyranoside. The coupling of two heptoglycans (12 and 13) was accomplished by a Lewis acid catalyst.