Synthesis of a β-GlcN-(1→4)-MurNAc building block en route to N-deacetylated peptidoglycan fragments

Some bacteria present a variation in their peptidoglycan structure that is the absence of the N-acetyl substituent in the glucosamine residue. Very recently, this structural modification was demonstrated to be critical for host innate immune evasion in Listeria monocytogenes. To shed light on the molecular details of the evasion mechanism, the synthesis of some N-deacetylated peptidoglycan fragments is needed. En route to this goal a high-yielding synthesis of a GlcN–MurNAc disaccharide building block has been accomplished. A careful study of the optimal protecting groups and reaction conditions was done to have a complete β-stereoselectivity in glycosylation as well as to ensure a high versatility to the disaccharide building block.