Synthesis of l-iduronic acid containing a common pentasaccharide repeating unit related to Escherichia coli O112ab and Shigella boydii serotype B15.

Abstract

Synthesis of an l-iduronic acid-containing identical O-antigenic pentasaccharide repeating unit related to the cell wall of E. coli O112ab and Shigella boydii serotype B15 has been successfully accomplished in satisfactory yield. The protected pentasaccharide was obtained via an efficient, stereoselective [2 + 3] block glycosylation strategy. A regioselective oxidation of primary hydroxyl groups to carboxylic acids was conducted using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and bis(acetoxy)iodobenzene (BAIB) at a later stage of the synthetic sequence to convert the l-idose to l-iduronic acid. The target pentasaccharide bearing an aminopropyl linker at the reducing end provides an opportunity for the formation of glycoconjugates with a suitable aglycon and other biological study.