An efficient synthetic route to N-glycosylamino acids using N α-Fmoc-Asp/Glu-5-oxazolidinone as internal protection

A new facile synthetic route to prepare N-glycosylamino acids in fewer steps is reported. 5-Oxazolidinone served as an effective protecting moiety for Nα-Fmoc-Asp/Glu and after glycosylation, the ring opening resulted in free α-carboxylic acid, which can be directly used to extend the chain to obtain N-glycopeptides. Both the minimum number of steps as well as circumvention of orthogonal protection strategy leads to a cost-effective route for their synthesis. This protocol can be easily scaled up to prepare N-glycosylated Asn/Gln acids in large quantities in fairly good yields. © Georg Thieme Verlag Stuttgart